View source for Medicine:Obsessive–compulsive disorder

{{Short description|Mental and behavioral disorder}}
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{{Infobox medical condition (new)
| name          = Obsessive–compulsive disorder
| image         = OCD handwash.jpg
| caption       = Frequent and excessive hand washing occurs in some people with OCD.
| field         = [[Biology:Psychiatry|Psychiatry]]
| symptoms      = Feel the need to check things repeatedly, perform [[Medicine:Compulsive behavior|certain routines repeatedly]], have [[Medicine:Intrusive thought|certain thoughts repeatedly]]<ref name="NIH20152" />
| complications = Tics, [[Medicine:Anxiety disorder|anxiety disorder]], [[Medicine:Suicide|suicide]]<ref name="DSM52" /><ref name="Ang2015">{{cite journal | vauthors = Angelakis I, Gooding P, Tarrier N, Panagioti M | title = Suicidality in obsessive compulsive disorder (OCD): a systematic review and meta-analysis | journal = Clinical Psychology Review | volume = 39 | pages = 1–15 | date = July 2015 | pmid = 25875222 | doi = 10.1016/j.cpr.2015.03.002 | publisher = Pergamon Press }}</ref>
| onset         = Before 35 years<ref name="NIH20152" /><ref name="DSM52" />
| risks         = Child abuse, stress<ref name="DSM52" />
| diagnosis     = Clinically based on symptoms; Y-BOCS is the gold standard tool to assess severity<ref name="DSM52" />
| differential  = Anxiety disorder, major depressive disorder, [[Medicine:Eating disorder|eating disorder]]s, [[Medicine:Tic disorder|tic disorder]]s, [[Medicine:Obsessive–compulsive personality disorder|obsessive–compulsive personality disorder]]<ref name="DSM52" />
| treatment     = [[Medicine:Psychotherapy|Counseling]], [[Chemistry:Selective serotonin reuptake inhibitor|selective serotonin reuptake inhibitor]]s, [[Chemistry:Clomipramine|clomipramine]]<ref name="NEJM2014" /><ref name="Ve2014" />
| frequency     = 2.3%<ref name="Good2014" />
}}
<!-- Definition and symptoms -->
'''Obsessive–compulsive disorder''' ('''OCD''') is a [[Medicine:Mental disorder|mental]] and [[Philosophy:Abnormality (behavior)|behavioral]] [[Disease#Disorder|disorder]] in which an individual has [[Medicine:Intrusive thought|intrusive thought]]s (an ''obsession'') and feels the need to perform certain routines (''compulsions'') repeatedly to relieve the distress caused by the obsession, to the extent where it impairs general function.<ref name="NIH20152">{{Cite web |last=The National Institute of Mental Health (NIMH) |date=January 2016 |title=What is Obsessive-Compulsive Disorder (OCD)? |url=http://www.nimh.nih.gov/health/topics/obsessive-compulsive-disorder-ocd/index.shtml |url-status=live |archive-url=https://web.archive.org/web/20160723194024/http://www.nimh.nih.gov/health/topics/obsessive-compulsive-disorder-ocd/index.shtml |archive-date=23 July 2016 |access-date=24 July 2016 |website=U.S. National Institutes of Health (NIH)}}</ref><ref name="DSM52">{{Cite book |isbn=978-0-89042-555-8 |url=https://archive.org/details/diagnosticstatis0005unse |title=Diagnostic and statistical manual of mental disorders: DSM-5 |date=2013 |edition=5th |location=Washington |pages=[https://archive.org/details/diagnosticstatis0005unse/page/237 237–242] |publisher=American Psychiatric Publishing}}</ref><ref name=":14">{{Cite web | vauthors =  Sartorius N, Henderson A, Strotzka H, Lipowski Z, Yu-cun S, You-xin X, Strömgren E, Glatzel J, Kühne G, Misès R, Soldatos C, Pull C, Giel R, Jegede R, Malt U, Nadzharov R, Smulevitch A, Hagberg B, Perris C, Scharfetter C, Clare A, Cooper J, Corbett J, Griffith Edwards J, Gelder M, Goldberg D, Gossop M, Graham P, Kendell R, Marks I, Russell G, Rutter M, Shepherd M, West D, Wing J, Wing L, Neki J, Benson F, Cantwell D, Guze S, Helzer J, Holzman P, Kleinman A, Kupfer D, Mezzich J, Spitzer R, Lokar J | display-authors = 6 |title=The ICD-10 Classification of Mental and Behavioural Disorders Clinical descriptions and diagnostic guidelines |website=who.int [[Organization:World Health Organization|World Health Organization]] |page=142 |url=https://apps.who.int/iris/bitstream/handle/10665/37958/9241544228_eng.pdf |access-date=8 August 2023}}</ref>

Obsessions are persistent unwanted thoughts, mental images, or urges that generate feelings of [[Medicine:Anxiety|anxiety]], [[Philosophy:Disgust|disgust]], or discomfort.<ref name=":0">{{Cite web |date=2021-02-16 |title=Overview – Obsessive compulsive disorder (OCD) |url=https://www.nhs.uk/mental-health/conditions/obsessive-compulsive-disorder-ocd/overview/ |access-date=2021-11-06 |website=nhs.uk |language=en}}</ref> Some common obsessions include fear of [[Chemistry:Contamination|contamination]], obsession with [[Symmetry|symmetry]], the fear of acting [[Religion:Blasphemy|blasphemously]], the sufferer's [[Social:Sexual orientation|sexual orientation]], and the fear of possibly harming others or themselves.<ref name="NIH20152" /><ref name=":4">{{Cite web |title=What Is Obsessive-Compulsive Disorder? |url=https://www.psychiatry.org/patients-families/ocd/what-is-obsessive-compulsive-disorder |access-date=2021-11-06 |website=psychiatry.org}}</ref> Compulsions are repeated actions or routines that occur in response to obsessions to achieve a relief from anxiety. Common compulsions include excessive hand washing, cleaning, [[Counting|counting]], ordering, repeating, avoiding triggers, [[Philosophy:Hoarding|hoarding]], neutralizing, seeking assurance, praying, and checking things.<ref name="NIH20152" /><ref name=":4" /><ref>{{Cite web |last=CDC |date=2020-12-02 |title=Obsessive-Compulsive Disorder in Children {{!}} CDC |url=https://www.cdc.gov/childrensmentalhealth/ocd.html |access-date=2021-11-06 |website=Centers for Disease Control and Prevention |language=en-us}}</ref> People with OCD may only perform mental compulsions such as needing to know or remember things. While this is sometimes referred to as [[Medicine:Primarily obsessional obsessive–compulsive disorder|primarily obsessional obsessive–compulsive disorder]] (Pure O), it is also considered a misnomer due to associated mental compulsions and reassurance seeking behaviors that are consistent with OCD.<ref>{{cite journal |last1=Williams |first1=Monnica T. |last2=Farris |first2=Samantha G. |last3=Turkheimer |first3=Eric |last4=Pinto |first4=Anthony |last5=Ozanick |first5=Krystal |last6=Franklin |first6=Martin E. |last7=Liebowitz |first7=Michael |last8=Simpson |first8=H. Blair |last9=Foa |first9=Edna B. |title=Myth of the pure obsessional type in obsessive-compulsive disorder |journal=Depression and Anxiety |date=June 2011 |volume=28 |issue=6 |pages=495–500 |doi=10.1002/da.20820|pmid=21509914 |pmc=3227121 |doi-access=free }}</ref>

Compulsions occur often and typically take up at least one hour per day, impairing one's quality of life.<ref name="NIH20152" /><ref name=":4" /><!-- Cause and diagnosis --> Compulsions cause relief in the moment, but cause obsessions to grow over time due to the repeated reward-seeking behavior of completing the ritual for relief. Many adults with OCD are aware that their compulsions do not make sense, but they still perform them to relieve the distress caused by obsessions.<ref name="NIH20152" /><ref name=":0" /><ref name=":4" /><ref name=":3">{{Cite web |title=What are compulsions? {{!}} OCD-UK |url=https://www.ocduk.org/ocd/compulsions/ |access-date=2021-11-05 |language=en-GB}}</ref> For this reason, thoughts and behaviors in OCD are usually considered [[Philosophy:Egosyntonic and egodystonic|egodystonic]]. In contrast, thoughts and behaviors in obsessive-compulsive personality disorder (OCPD) are usually considered [[Philosophy:Egosyntonic and egodystonic|egosyntonic]], helping differentiate between the two.<ref name="The role of personality disorders i">{{cite journal |last1=Thamby |first1=Abel |last2=Khanna |first2=Sumant |title=The role of personality disorders in obsessive-compulsive disorder |journal=Indian Journal of Psychiatry |date=2019 |volume=61 |issue=7 |pages=S114–S118 |doi=10.4103/psychiatry.IndianJPsychiatry_526_18 |pmid=30745684 |pmc=6343421 |doi-access=free}}</ref>

Although the exact cause of OCD is unknown, several regions of the brain have been implicated in its neuroanatomical model including the [[Biology:Anterior cingulate cortex|anterior cingulate cortex]], [[Biology:Orbitofrontal cortex|orbitofrontal cortex]], [[Medicine:Amygdala|amygdala]], and BNST.<ref>{{cite journal |last1=Huey |first1=E. D. |last2=Zahn |first2=R. |last3=Krueger |first3=F. |last4=Moll |first4=J. |last5=Kapogiannis |first5=D. |last6=Wassermann |first6=E. M. |last7=Grafman |first7=J. |title=A Psychological and Neuroanatomical Model of Obsessive-Compulsive Disorder |journal=Journal of Neuropsychiatry |date=1 November 2008 |volume=20 |issue=4 |pages=390–408 |doi=10.1176/appi.neuropsych.20.4.390|pmid=19196924 |pmc=4476073 }}</ref><ref name="NIH20152" /> The presence of a [[Biology:Genetics|genetic]] component is evidenced by the increased likelihood for both identical twins to be affected than both fraternal twins.<ref>{{cite journal |last1=Browne |first1=Heidi A. |last2=Gair |first2=Shannon L. |last3=Scharf |first3=Jeremiah M. |last4=Grice |first4=Dorothy E. |title=Genetics of Obsessive-Compulsive Disorder and Related Disorders |journal=Psychiatric Clinics of North America |date=September 2014 |volume=37 |issue=3 |pages=319–335 |doi=10.1016/j.psc.2014.06.002 |pmid=25150565 |pmc=4143777 }}</ref> Risk factors include a history of child abuse or other stress-inducing events such as during the postpartum period or after streptococcal infections.<ref name="NIH20152" /><ref name="Symptoms of Obsessive-Compulsive Di">{{cite journal |last1=Starcevic |first1=Vladan |last2=Eslick |first2=Guy D. |last3=Viswasam |first3=Kirupamani |last4=Berle |first4=David |title=Symptoms of Obsessive-Compulsive Disorder during Pregnancy and the Postpartum Period: a Systematic Review and Meta-Analysis |journal=Psychiatric Quarterly |date=December 2020 |volume=91 |issue=4 |pages=965–981 |doi=10.1007/s11126-020-09769-8|pmid=32445002 |s2cid=218772347 }}</ref> Diagnosis is based on clinical presentation and requires ruling out other drug-related or medical causes; rating scales such as the Yale–Brown Obsessive–Compulsive Scale (Y-BOCS) assess severity.<ref name="DSM52" /><ref name="Fenske_2009">{{cite journal | vauthors = Fenske JN, Schwenk TL | title = Obsessive compulsive disorder: diagnosis and management | journal = American Family Physician | volume = 80 | issue = 3 | pages = 239–245 | date = August 2009 | pmid = 19621834 | url = http://www.aafp.org/afp/2009/0801/p239.html | url-status = live | archive-url = https://web.archive.org/web/20140512222223/http://www.aafp.org/afp/2009/0801/p239.html | archive-date = 12 May 2014 }}</ref> Other disorders with similar symptoms include [[Medicine:Generalized anxiety disorder|generalized anxiety disorder]], major depressive disorder, [[Medicine:Eating disorder|eating disorder]]s, [[Medicine:Tic disorder|tic disorder]]s, body-focused repetitive behavior, and [[Medicine:Obsessive–compulsive personality disorder|obsessive–compulsive personality disorder]].<ref name="DSM52" /> Personality disorders are a common comorbidity, with schizotypal and OCPD having poor treatment response.<ref name="The role of personality disorders i"/> The condition is also associated with a general increase in [[Medicine:Suicide|suicidality]].<ref name="Ang2015" /><ref>{{cite journal | vauthors = Alonso P, Segalàs C, Real E, Pertusa A, Labad J, Jiménez-Murcia S, Jaurrieta N, Bueno B, Vallejo J, Menchón JM | display-authors = 6 | title = Suicide in patients treated for obsessive-compulsive disorder: a prospective follow-up study | journal = Journal of Affective Disorders | volume = 124 | issue = 3 | pages = 300–308 | date = August 2010 | pmid = 20060171 | doi = 10.1016/j.jad.2009.12.001 }}</ref><ref>{{cite journal |last1=Albert |first1=Umberto |last2=De Ronchi |first2=Diana |last3=Maina |first3=Giuseppe |last4=Pompili |first4=Maurizio |title=Suicide Risk in Obsessive-Compulsive Disorder and Exploration of Risk Factors: A Systematic Review |journal=Current Neuropharmacology |date=25 July 2019 |volume=17 |issue=8 |pages=681–696 |doi=10.2174/1570159X16666180620155941 |pmid=29929465 |pmc=7059158 }}</ref> The phrase ''obsessive–compulsive'' is sometimes used in an informal manner unrelated to OCD to describe someone as excessively meticulous, [[Philosophy:Perfectionism (psychology)|perfectionistic]], absorbed, or otherwise fixated.<ref name=":5">{{Cite book | vauthors = Bynum WF, Porter R, Shepherd M |title=The anatomy of madness: essays in the history of psychiatry |date=1985 |publisher=[[Company:Routledge|Routledge]] |isbn=978-0-415-32382-6 |location=London |pages=166–187 |chapter=Obsessional Disorders: A Conceptual History. Terminological and Classificatory Issues.}}</ref> However, the actual disorder can vary in presentation, and individuals with OCD may not be concerned with cleanliness or symmetry.

<!-- Treatment and prognosis -->
OCD is chronic and long-lasting with periods of severe symptoms followed by periods of improvement.<ref name=":10" /><ref>{{Cite web |title=Obsessive-compulsive disorder: MedlinePlus Medical Encyclopedia |url=https://medlineplus.gov/ency/article/000929.htm |access-date=2023-04-25 |website=medlineplus.gov |language=en}}</ref> Treatment can improve ability to function and quality of life, and is usually reflected by improved Y-BOCS scores.<ref>{{Cite web |date=October 2022 |title=What Is Obsessive-Compulsive Disorder? |url=https://www.psychiatry.org/patients-families/obsessive-compulsive-disorder/what-is-obsessive-compulsive-disorder |access-date=2023-04-25 |website=American Psychiatric Association}}</ref> Treatment for OCD may involve [[Medicine:Psychotherapy|psychotherapy]], [[Medicine:Pharmacotherapy|pharmacotherapy]] such as [[Chemistry:Antidepressant|antidepressant]]s, or [[Medicine:Surgery|surgical]] procedures such as [[Biology:Deep brain stimulation|deep brain stimulation]] or, in extreme cases, [[Unsolved:Psychosurgery|psychosurgery]].<ref name="NEJM2014">{{cite journal |vauthors=Grant JE |date=August 2014 |title=Clinical practice: Obsessive-compulsive disorder |journal=The New England Journal of Medicine |volume=371 |issue=7 |pages=646–653 |doi=10.1056/NEJMcp1402176 |pmid=25119610}}</ref><ref name="Ve2014" /><ref name=":6">{{Cite web |title=Medications Approved for Treatment of OCD |url=https://beyondocd.org/ocd-facts/approved-medications |access-date=11 December 2021 |website=Beyond OCD: OCD Information and Resources}}</ref><ref>{{cite journal | vauthors = Pittenger C, Bloch MH | title = Pharmacological treatment of obsessive-compulsive disorder | journal = The Psychiatric Clinics of North America | volume = 37 | issue = 3 | pages = 375–391 | date = September 2014 | pmid = 25150568 | pmc = 4143776 | doi = 10.1016/j.psc.2014.05.006 }}</ref> Psychotherapies derived from [[Medicine:Cognitive behavioral therapy|cognitive behavioral therapy]] (CBT) models, such as exposure and response prevention, [[Philosophy:Acceptance and commitment therapy|acceptance and commitment therapy]], and [[Medicine:Inference-based therapy|inference based-therapy]], are more effective than non-CBT interventions.<ref name=":17" /> SSRIs are more effective when used in excess of the recommended depression dosage; however, higher doses can increase side effect intensity.<ref name=":7">{{cite journal | vauthors = Bloch MH, McGuire J, Landeros-Weisenberger A, Leckman JF, Pittenger C | title = Meta-analysis of the dose-response relationship of SSRI in obsessive-compulsive disorder | journal = Molecular Psychiatry | volume = 15 | issue = 8 | pages = 850–855 | date = August 2010 | pmid = 19468281 | pmc = 2888928 | doi = 10.1038/mp.2009.50 }}</ref> Commonly used SSRIs include [[Chemistry:Sertraline|sertraline]], [[Chemistry:Fluoxetine|fluoxetine]], [[Chemistry:Fluvoxamine|fluvoxamine]], [[Chemistry:Paroxetine|paroxetine]], [[Chemistry:Citalopram|citalopram]], and [[Chemistry:Escitalopram|escitalopram]].<ref name=":6" /> Some patients fail to improve after taking the maximum tolerated dose of multiple SSRIs for at least two months; these cases qualify as treatment-resistant and can require second-line treatment such as [[Chemistry:Clomipramine|clomipramine]] or [[Chemistry:Atypical antipsychotic|atypical antipsychotic]] augmentation.<ref name="NEJM2014" /><ref name="Ve2014">{{cite journal | vauthors = Veale D, Miles S, Smallcombe N, Ghezai H, Goldacre B, Hodsoll J | title = Atypical antipsychotic augmentation in SSRI treatment refractory obsessive-compulsive disorder: a systematic review and meta-analysis | journal = BMC Psychiatry | volume = 14 | page = 317 | date = November 2014 | pmid = 25432131 | pmc = 4262998 | doi = 10.1186/s12888-014-0317-5 | doi-access = free }}</ref><ref name=":7" /><ref name="Dec2010">{{cite journal | vauthors = Decloedt EH, Stein DJ | title = Current trends in drug treatment of obsessive-compulsive disorder | journal = Neuropsychiatric Disease and Treatment | volume = 6 | pages = 233–242 | date = May 2010 | pmid = 20520787 | pmc = 2877605 | doi = 10.2147/NDT.S3149 | doi-access = free }}</ref> While SSRIs continue to be first-line, recent data for treatment-resistant OCD supports adjunctive use of neuroleptic medications, deep-brain stimulation, and neurosurgical ablation.<ref>{{cite journal |last1=Hirschtritt |first1=Matthew E. |last2=Bloch |first2=Michael H. |last3=Mathews |first3=Carol A. |title=Obsessive-Compulsive Disorder: Advances in Diagnosis and Treatment |journal=JAMA |date=4 April 2017 |volume=317 |issue=13 |pages=1358–1367 |doi=10.1001/jama.2017.2200|pmid=28384832 |s2cid=13660201 }}</ref> There is growing evidence to support the use of [[Biology:Deep brain stimulation|deep brain stimulation]] and repetitive transcranial magnetic stimulation for treatment-resistant obsessive-compulsive disorder.<ref>{{cite journal |last1=Gadot |first1=Ron |last2=Najera |first2=Ricardo |last3=Hirani |first3=Samad |last4=Anand |first4=Adrish |last5=Storch |first5=Eric |last6=Goodman |first6=Wayne K |last7=Shofty |first7=Ben |last8=Sheth |first8=Sameer A |title=Efficacy of deep brain stimulation for treatment-resistant obsessive-compulsive disorder: systematic review and meta-analysis |journal=Journal of Neurology, Neurosurgery & Psychiatry |date=November 2022 |volume=93 |issue=11 |pages=1166–1173 |doi=10.1136/jnnp-2021-328738|pmid=36127157 |doi-access=free }}</ref><ref>{{cite journal |last1=Fitzsimmons |first1=Sophie M.D.D. |last2=van der Werf |first2=Ysbrand D. |last3=van Campen |first3=A. Dilene |last4=Arns |first4=Martijn |last5=Sack |first5=Alexander T. |last6=Hoogendoorn |first6=Adriaan W. |last7=van den Heuvel |first7=Odile A. |last8=van Balkom |first8=Anton J.L.M. |last9=Batelaan |first9=Neeltje M. |last10=Eijndhoven |first10=Philip van |last11=Hendriks |first11=Gert-Jan |last12=Oostrom |first12=Iris van |last13=Oppena |first13=Patricia van |last14=Schruers |first14=Koen R.J. |last15=Tendolkar |first15=Indira |last16=Vriend |first16=Chris |title=Repetitive transcranial magnetic stimulation for obsessive-compulsive disorder: A systematic review and pairwise/network meta-analysis |journal=Journal of Affective Disorders |date=April 2022 |volume=302 |pages=302–312 |doi=10.1016/j.jad.2022.01.048|pmid=35041869 |doi-access=free |hdl=2066/247522 |hdl-access=free }}</ref>

<!-- Epidemiology, Society and Culture -->
Obsessive–compulsive disorder affects about 2.3% of people at some point in their lives, while rates during any given year are about 1.2%.<ref name="DSM52" /><ref name="Good2014">{{cite journal | vauthors = Goodman WK, Grice DE, Lapidus KA, Coffey BJ | title = Obsessive-compulsive disorder | journal = The Psychiatric Clinics of North America | volume = 37 | issue = 3 | pages = 257–267 | date = September 2014 | pmid = 25150561 | doi = 10.1016/j.psc.2014.06.004 }}</ref> More than three million Americans suffer from OCD.<ref>{{Cite web |date=2023-02-15 |title=Diagnosis and Treatment of Obsessive-Compulsive Disorder in Children and Adolescents (A Systematic Review) |url=https://www.pcori.org/research-results/2023/diagnosis-and-treatment-obsessive-compulsive-disorder-children-and-adolescents-systematic-review |access-date=2023-04-28 |website=Diagnosis and Treatment of Obsessive-Compulsive Disorder in Children and Adolescents (A Systematic Review) {{!}} PCORI |language=en}}</ref> According to Mercy, approximately 1 in 40 U.S. adults and 1 in 100 U.S. children have OCD.<ref>{{Cite web |title=Obsessive Compulsive Disorder |url=https://www.mercy.net/service/obsessive-compulsive-disorder |access-date=2023-03-24 |website=Mercy |language=en}}</ref> Although possible at times with triggers such as pregnancy, onset rarely occurs after age 35, and about 50% of patients experience detrimental effects to daily life before age 20.<ref name="NIH20152" /><ref name="Symptoms of Obsessive-Compulsive Di"/><ref name="DSM52" /><ref>{{cite journal |last1=Miller |first1=ES |last2=Chu |first2=C |last3=Gollan |first3=J |last4=Gossett |first4=DR |title=Obsessive-compulsive symptoms during the postpartum period. A prospective cohort. |journal=The Journal of Reproductive Medicine |date=March 2013 |volume=58 |issue=3–4 |pages=115–22 |pmid=23539879|pmc=5705036 }}</ref> While OCD occurs worldwide,<ref name="NIH20152" /><ref name="DSM52" /> a recent meta-analysis showed that women are 1.6 times more likely to experience OCD.<ref name="Women Are at Greater Risk of OCD Th">{{cite journal |last1=Fawcett |first1=Emily J. |last2=Power |first2=Hilary |last3=Fawcett |first3=Jonathan M. |title=Women Are at Greater Risk of OCD Than Men: A Meta-Analytic Review of OCD Prevalence Worldwide |journal=The Journal of Clinical Psychiatry |date=23 June 2020 |volume=81 |issue=4 |doi=10.4088/JCP.19r13085|pmid=32603559 |s2cid=220288984 }}</ref> Based on data from 34 studies, the worldwide prevalence rate is 1.5% in women and 1% in men.<ref name="Women Are at Greater Risk of OCD Th"/>


== Signs and symptoms ==
OCD can present with a wide variety of symptoms. Certain groups of symptoms usually occur together as dimensions or clusters, which may reflect an underlying process. The standard assessment tool for OCD, the Yale–Brown Obsessive Compulsive Scale (Y-BOCS), has 13 predefined categories of symptoms. These symptoms fit into three to five groupings.<ref name="Leckman">{{cite journal | vauthors = Leckman JF, Bloch MH, King RA | title = Symptom dimensions and subtypes of obsessive-compulsive disorder: a developmental perspective | journal = Dialogues in Clinical Neuroscience | volume = 11 | issue = 1 | pages = 21–33 | date = 2009 | pmid = 19432385 | pmc = 3181902 | doi = 10.31887/DCNS.2009.11.1/jfleckman }}</ref> A [[Meta-analysis|meta-analytic]] review of symptom structures found a four-factor grouping structure to be most reliable: symmetry factor, forbidden thoughts factor, cleaning factor, and hoarding factor. The symmetry factor correlates highly with obsessions related to ordering, counting, and symmetry, as well as repeating compulsions. The forbidden thoughts factor correlates highly with intrusive thoughts of a violent, religious, or sexual nature. The cleaning factor correlates highly with obsessions about contamination and compulsions related to cleaning. The hoarding factor only involves hoarding-related obsessions and compulsions, and was identified as being distinct from other symptom groupings.<ref>{{cite journal | vauthors = Bloch MH, Landeros-Weisenberger A, Rosario MC, Pittenger C, Leckman JF | title = Meta-analysis of the symptom structure of obsessive-compulsive disorder | journal = The American Journal of Psychiatry | volume = 165 | issue = 12 | pages = 1532–1542 | date = December 2008 | pmid = 18923068 | pmc = 3972003 | doi = 10.1176/appi.ajp.2008.08020320 }}</ref>

When looking into the onset of OCD, one study suggests that there are differences in the age of onset between males and females, with the average age of onset of OCD being 9.6 for male children and 11.0 for female children.<ref name="Obsessive-Compulsive Disorder in Ch">{{cite journal |last1=Swedo |first1=Susan E. |title=Obsessive-Compulsive Disorder in Children and Adolescents: Clinical Phenomenology of 70 Consecutive Cases |journal=Archives of General Psychiatry |date=1 April 1989 |volume=46 |issue=4 |pages=335–341 |doi=10.1001/archpsyc.1989.01810040041007|pmid=2930330 }}</ref> When looking at both adults and children a study found the average ages of onset to be 21 and 24 for males and females respectively.<ref>{{cite journal |last1=Rasmussen |first1=SA |last2=Eisen |first2=JL |title=The epidemiology and clinical features of obsessive compulsive disorder. |journal=The Psychiatric Clinics of North America |date=December 1992 |volume=15 |issue=4 |pages=743–58 |doi=10.1016/S0193-953X(18)30205-3 |pmid=1461792}}</ref> While some studies have shown that OCD with earlier onset is associated with greater severity, other studies have not been able to validate this finding.<ref>{{cite journal |last1=Kenyon |first1=Katherine M. |last2=Eaton |first2=Warren O. |title=Age at child obsessive-compulsive disorder onset and its relation to gender, symptom severity, and family functioning. |journal=Archives of Scientific Psychology |date=16 November 2015 |volume=3 |issue=1 |pages=150–158 |doi=10.1037/arc0000022|doi-access=free |hdl=1993/30297 |hdl-access=free }}</ref> Looking at women specifically, a different study suggested that 62% of participants found that their symptoms worsened at a premenstrual age. Across the board, all demographics and studies showed a mean age of onset of less than 25.<ref name=":16">{{Cite web |title=About OCD |url=https://med.stanford.edu/ocd/about.html |access-date=2022-12-13 |website=Obsessive-Compulsive and Related Disorders |language=sm}}</ref>

Some OCD subtypes have been associated with improvement in performance on certain tasks, such as [[Philosophy:Pattern recognition (psychology)|pattern recognition]] (washing subtype) and spatial working memory (obsessive thought subtype). Subgroups have also been distinguished by [[Biology:Neuroimaging|neuroimaging]] findings and treatment response, though neuroimaging studies have not been comprehensive enough to draw conclusions. Subtype-dependent treatment response has been studied, and the hoarding subtype has consistently been least responsive to treatment.<ref>{{cite journal | vauthors = McKay D, Abramowitz JS, Calamari JE, Kyrios M, Radomsky A, Sookman D, Taylor S, Wilhelm S | display-authors = 6 | title = A critical evaluation of obsessive-compulsive disorder subtypes: symptoms versus mechanisms | journal = Clinical Psychology Review | volume = 24 | issue = 3 | pages = 283–313 | date = July 2004 | pmid = 15245833 | doi = 10.1016/j.cpr.2004.04.003 }}</ref>

While OCD is considered a [[Physics:Homogeneous|homogeneous]] disorder from a [[Social:Neuropsychology|neuropsychological]] perspective, many of the symptoms may be the result of [[Medicine:Comorbidity|comorbid]] disorders. For example, adults with OCD have exhibited more symptoms of [[Medicine:Attention deficit hyperactivity disorder|attention–deficit/hyperactivity disorder]] (ADHD) and [[Medicine:Autism spectrum|autism spectrum disorder]] (ASD) than adults without OCD.<ref>{{cite journal | vauthors = Anholt GE, Cath DC, van Oppen P, Eikelenboom M, Smit JH, van Megen H, van Balkom AJ | title = Autism and ADHD symptoms in patients with OCD: are they associated with specific OC symptom dimensions or OC symptom severity? | journal = Journal of Autism and Developmental Disorders | volume = 40 | issue = 5 | pages = 580–589 | date = May 2010 | pmid = 20039111 | pmc = 2855859 | doi = 10.1007/s10803-009-0922-1 }}</ref>

In regards to the cause of onset, researchers asked participants in one study<ref name=":16" /> what they felt was responsible for triggering the initial onset of their illness. 29% of patients answered that there was an environmental factor in their life that did so. Specifically, the majority of participants who answered with that noted their environmental factor to be related to an increased responsibility.

=== Obsessions ===
{{Main|Medicine:Intrusive thought}}
[[File:Hortus Deliciarum - Hell.jpg|thumb|People with OCD may face intrusive thoughts, such as thoughts about the devil (shown is a painted interpretation of Hell).]]

Obsessions are stress-inducing thoughts that recur and persist, despite efforts to ignore or confront them.<ref name="Review10">{{cite journal |vauthors=Markarian Y, Larson MJ, Aldea MA, Baldwin SA, Good D, Berkeljon A, Murphy TK, Storch EA, McKay D |display-authors=6 |title=Multiple pathways to functional impairment in obsessive-compulsive disorder |journal=Clinical Psychology Review |volume=30 |issue=1 |pages=78–88 |date=February 2010 |pmid=19853982 |doi=10.1016/j.cpr.2009.09.005 |url=https://scholarsarchive.byu.edu/facpub/6053 }}</ref> People with OCD frequently perform tasks, or [[Medicine:Compulsive behavior|compulsions]], to seek relief from obsession-related anxiety. Within and among individuals, initial obsessions vary in clarity and vividness. A relatively vague obsession could involve a general sense of disarray or tension, accompanied by a belief that life cannot proceed as normal while the imbalance remains. A more intense obsession could be a preoccupation with the thought or image of a close family member or friend dying, or intrusive thoughts related to [[Medicine:Relationship obsessive–compulsive disorder|relationship rightness]].<ref name="Doron2013">{{cite journal | vauthors = Doron G, Szepsenwol O, Karp E, Gal N | title = Obsessing about intimate-relationships: testing the double relationship-vulnerability hypothesis | journal = Journal of Behavior Therapy and Experimental Psychiatry | volume = 44 | issue = 4 | pages = 433–440 | date = December 2013 | pmid = 23792752 | doi = 10.1016/j.jbtep.2013.05.003 }}</ref>{{sfn|Baer|2001|p=xiv}} Other obsessions concern the possibility that someone or something other than oneself—such as [[Religion:God|God]], the [[Philosophy:Devil|devil]], or [[Disease|disease]]—will harm either the patient or the people or things the patient cares about. Others with OCD may experience the sensation of invisible protrusions emanating from their bodies, or feel that [[Philosophy:Animism|inanimate objects are ensouled]].<ref name="Mash">{{Cite book | vauthors = Mash EJ, Wolfe DA |title=Abnormal child psychology  |date=2005 |publisher=Thomson Wadsworth |isbn=978-1-305-10542-3 |edition = 3rd |location= Belmont, California |page=197}}</ref>

Some people with OCD experience [[Medicine:Sexual obsessions|sexual obsessions]] that may involve intrusive thoughts or images of "kissing, touching, fondling, oral sex, anal sex, [[Biology:Sexual intercourse|intercourse]], [[Social:Incest|incest]], and [[Medicine:Rape|rape]]" with "strangers, acquaintances, parents, children, family members, friends, coworkers, animals, and religious figures", and can include [[Social:Heterosexuality|heterosexual]] or [[Social:Homosexuality|homosexual]] contact with people of any age.<ref name="Osgood">{{Cite web |vauthors = Osgood-Hynes D |title=Thinking Bad Thoughts |url=http://www.raminader.com/PDFs%20Uploaded/OCD%20-%20Thinking%20Bad%20Thoughts.pdf |archive-url=https://web.archive.org/web/20111115230001/http://raminader.com/PDFs%20Uploaded/OCD%20-%20Thinking%20Bad%20Thoughts.pdf |archive-date=15 November 2011 |access-date=30 December 2006 |publisher=MGH/McLean OCD Institute |location=Belmont, Massachusetts}}</ref> Similar to other intrusive thoughts or images, some disquieting sexual thoughts are normal at times, but people with OCD may attach extraordinary significance to such thoughts. For example, obsessive fears about [[Social:Sexual orientation|sexual orientation]] can appear to the affected individual, and even to those around them, as a crisis of [[Philosophy:Sexual identity|sexual identity]].<ref name="hocd">{{Cite web | vauthors = Williams M |title=Sexual Orientation Worries in Obsessive-Compulsive Disorder |url=https://www.ocdtypes.com/so-ocd_hocd.php |access-date=4 February 2021 |website=OCD Types}}</ref><ref name="so-ocd">{{cite journal | vauthors = Williams MT, Farris SG | title = Sexual orientation obsessions in obsessive-compulsive disorder: prevalence and correlates | journal = Psychiatry Research | volume = 187 | issue = 1–2 | pages = 156–159 | date = May 2011 | pmid = 21094531 | pmc = 3070770 | doi = 10.1016/j.psychres.2010.10.019 | publisher = [[Company:Elsevier|Elsevier]] }}</ref> Furthermore, the doubt that accompanies OCD leads to uncertainty regarding whether one might act on the troubling thoughts, resulting in self-criticism or self-loathing.<ref name="Osgood" />

Most people with OCD understand that their thoughts do not correspond with reality; however, they feel that they must act as though these ideas are correct or realistic. For example, someone who engages in [[Medicine:Compulsive hoarding|compulsive hoarding]] might be inclined to treat inorganic matter as if it had the sentience or rights of living organisms, despite accepting that such behavior is irrational on an intellectual level. There is debate as to whether hoarding should be considered an independent syndrome from OCD.<ref>{{cite journal | vauthors = Murphy DL, Timpano KR, Wheaton MG, Greenberg BD, Miguel EC | title = Obsessive-compulsive disorder and its related disorders: a reappraisal of obsessive-compulsive spectrum concepts | journal = Dialogues in Clinical Neuroscience | volume = 12 | issue = 2 | pages = 131–148 | date = 2010 | pmid = 20623919 | pmc = 3181955 | doi = 10.31887/DCNS.2010.12.2/dmurphy | publisher = Taylor & Francis }}</ref>

=== Compulsions ===
{{Main|Medicine:Compulsive behavior}}

[[File:Derma me.JPG|thumb|upright=1.35|A person exhibiting [[Medicine:Excoriation disorder|skin-picking disorder]]]]
Some people with OCD perform compulsive rituals because they inexplicably feel that they must do so, while others act compulsively to mitigate the anxiety that stems from obsessive thoughts. The affected individual might feel that these actions will either prevent a dreaded event from occurring, or push the event from their thoughts. In any case, their reasoning is so [[Medicine:Idiosyncrasy|idiosyncratic]] or distorted that it results in significant distress, either personally, or for those around the affected individual. Excessive [[Medicine:Excoriation disorder|skin picking]], [[Medicine:Trichotillomania|hair pulling]], [[Medicine:Nail biting|nail biting]], and other body-focused repetitive behavior disorders are all on the obsessive–compulsive spectrum.<ref name="DSM52" /> Some individuals with OCD are aware that their behaviors are not rational, but they feel compelled to follow through with them to fend off feelings of panic or dread.<ref>{{Citation |title=Highlights of Changes from DSM-IV-TR to DSM-5 |url=http://www.dsm5.org/documents/changes%20from%20dsm-iv-tr%20to%20dsm-5.pdf |page=7 |year=2013 |archive-url=https://web.archive.org/web/20131019204551/http://www.dsm5.org/Documents/changes%20from%20dsm-iv-tr%20to%20dsm-5.pdf |publisher=American Psychiatric Association |access-date=12 April 2016 |archive-date=19 October 2013 |url-status=live}}</ref> Furthermore, compulsions often stem from [[Medicine:Memory distrust syndrome|memory distrust]], a symptom of OCD characterized by insecurity in one's skills in [[Perception|perception]], [[Philosophy:Attention|attention]], and [[Memory|memory]], even in cases where there is no clear evidence of a deficit.<ref>{{cite journal | vauthors = Hermans D, Engelen U, Grouwels L, Joos E, Lemmens J, Pieters G | title = Cognitive confidence in obsessive-compulsive disorder: distrusting perception, attention and memory | journal = Behaviour Research and Therapy | volume = 46 | issue = 1 | pages = 98–113 | date = January 2008 | pmid = 18076865 | doi = 10.1016/j.brat.2007.11.001 | publisher = [[Company:Elsevier|Elsevier]] }}</ref>

Common compulsions may include hand washing, cleaning, checking things (such as locks on doors), repeating actions (such as repeatedly turning on and off switches), ordering items in a certain way, and requesting reassurance.<ref>{{cite book |url=https://books.google.com/books?id=3UUuXw7ISM0C&pg=PA418 |title=Psychiatric Nursing: Contemporary Practice |vauthors=Boyd MA |publisher=Lippincott Williams & Wilkins |year=2007 |isbn=978-0-397-55178-1 |location=Baltimore, Maryland}}</ref><ref>{{Cite journal |title=Integration of Psychosocial Rehabilitation Into Psychiatric Nursing Practice |journal=Issues in Mental Health Nursing |volume=15 |issue=1 |pages=13–26 |doi=10.3109/01612849409074930 |pmid=8119793 |date=1994 |last1=Boyd |first1=Mary Ann }}</ref> Although some individuals perform actions repeatedly, they do not necessarily perform these actions compulsively; for example, morning or nighttime routines and religious practices are not usually compulsions. Whether behaviors qualify as compulsions or mere habit depends on the context in which they are performed. For instance, arranging and ordering books for eight hours a day would be expected of someone who works in a library, but this routine would seem abnormal in other situations. In other words, habits tend to bring efficiency to one's life, while compulsions tend to disrupt it.<ref>{{Cite web |title=Obsessive-Compulsive Disorder, (2005) |url=http://www.webmd.com/anxiety-panic/guide/obsessive-compulsive-disorder. |access-date=15 December 2009}}</ref> Furthermore, compulsions are different from tics (such as touching, tapping, rubbing, or blinking) and [[Medicine:Stereotypic movement disorder|stereotyped movements]] (such as head banging, body rocking, or self-biting), which are usually not as complex and not precipitated by obsessions.<ref>{{cite journal | vauthors = Storch EA, Stigge-Kaufman D, Marien WE, Sajid M, Jacob ML, Geffken GR, Goodman WK, Murphy TK | display-authors = 6 | title = Obsessive-compulsive disorder in youth with and without a chronic tic disorder | journal = Depression and Anxiety | volume = 25 | issue = 9 | pages = 761–767 | year = 2008 | pmid = 17345600 | doi = 10.1002/da.20304 | s2cid = 30858531 | doi-access = free }}</ref> It can sometimes be difficult to tell the difference between compulsions and complex tics, and about 10–40% of people with OCD also have a lifetime tic disorder.<ref name="DSM52" /><ref>{{cite journal | vauthors = Conelea CA, Walther MR, Freeman JB, Garcia AM, Sapyta J, Khanna M, Franklin M | title = Tic-related obsessive-compulsive disorder (OCD): phenomenology and treatment outcome in the Pediatric OCD Treatment Study II | journal = Journal of the American Academy of Child and Adolescent Psychiatry | volume = 53 | issue = 12 | pages = 1308–1316 | date = December 2014 | pmid = 25457929 | pmc = 4254546 | doi = 10.1016/j.jaac.2014.09.014 }}</ref>

People with OCD rely on compulsions as an escape from their obsessive thoughts; however, they are aware that relief is only temporary, and that intrusive thoughts will return. Some affected individuals use compulsions to avoid situations that may trigger obsessions. Compulsions may be actions directly related to the obsession, such as someone obsessed with contamination compulsively washing their hands, but they can be unrelated as well.<ref name=":4" /> In addition to experiencing the anxiety and fear that typically accompanies OCD, affected individuals may spend hours performing compulsions every day. In such situations, it can become difficult for the person to fulfill their work, familial, or social roles. These behaviors can also cause adverse physical symptoms; for example, people who obsessively wash their hands with [[Biology:Antibacterial soap|antibacterial soap]] and hot water can make their skin red and raw with [[Medicine:Dermatitis|dermatitis]].<ref>{{Cite web |title=Hygiene of the Skin: When Is Clean Too Clean? Subtopic: "Skin Barrier Properties and Effect of Hand Hygiene Practices", Paragraph 5. |url=https://www.cdc.gov/ncidod/eid/vol7no2/larson.htm |archive-url=https://web.archive.org/web/20090421205614/http://www.cdc.gov/ncidod/eid/vol7no2/larson.htm |archive-date=21 April 2009 |access-date=26 March 2009 |url-status=live}}</ref>

Individuals with OCD often use [[Philosophy:Rationalization (psychology)|rationalizations]] to explain their behavior; however, these rationalizations do not apply to the behavioral pattern, but to each individual occurrence. For example, someone compulsively checking the front door may argue that the time and stress associated with one check is less than the time and stress associated with being robbed, and checking is consequently the better option. This reasoning often occurs in a cyclical manner, and can continue for as long as the affected person needs it to in order to feel safe.<ref>{{cite journal | vauthors = Pélissier MC, O'Connor KP | title = Deductive and inductive reasoning in obsessive-compulsive disorder | journal = The British Journal of Clinical Psychology | volume = 41 | issue = Pt 1 | pages = 15–27 | date = March 2002 | pmid = 11931675 | doi = 10.1348/014466502163769 | publisher = [[Company:Wiley-Blackwell|Wiley-Blackwell]] }}</ref>

In cognitive behavioral therapy (CBT), OCD patients are asked to overcome intrusive thoughts by not indulging in any compulsions. They are taught that rituals keep OCD strong, while not performing them causes OCD to become weaker.<ref>{{Cite web |title=Understanding CBT for OCD |url=https://www.med.upenn.edu/ctsa/forms_ocd_cbt.html |access-date=31 August 2021 |publisher=Perelman School of Medicine University of Pennsylvania}}</ref> This position is supported by the pattern of memory distrust; the more often compulsions are repeated, the more weakened memory trust becomes, and this cycle continues as memory distrust increases compulsion frequency.<ref>{{cite journal | vauthors = van den Hout M, Kindt M | title = Obsessive-compulsive disorder and the paradoxical effects of perseverative behaviour on experienced uncertainty | journal = Journal of Behavior Therapy and Experimental Psychiatry | volume = 35 | issue = 2 | pages = 165–181 | date = June 2004 | pmid = 15210377 | doi = 10.1016/j.jbtep.2004.04.007 | s2cid = 21371127 | hdl = 1874/11267 | hdl-access = free }}</ref> For body-focused repetitive behaviors (BFRB) such as [[Medicine:Trichotillomania|trichotillomania]] (hair pulling), [[Medicine:Excoriation disorder|skin picking]], and [[Medicine:Nail biting|onychophagia]] (nail biting), behavioral interventions such as habit reversal training and [[Medicine:Decoupling for body-focused repetitive behaviors|decoupling]] are recommended for the treatment of compulsive behaviors.<ref name=":1">{{Cite journal | vauthors = Himle MB, Flessner CA, Woods DW |date=2004 |title=Advances in the behavior analytic treatment of trichotillomania and Tourette's Syndrome. |journal=Journal of Early and Intensive Behavior Intervention |volume=1 |issue=1 |pages=57–64 |doi=10.1037/h0100282 |issn=1554-4893}}</ref><ref name=":2">{{cite journal | vauthors = Sarris J, Camfield D, Berk M | title = Complementary medicine, self-help, and lifestyle interventions for obsessive compulsive disorder (OCD) and the OCD spectrum: a systematic review | journal = Journal of Affective Disorders | volume = 138 | issue = 3 | pages = 213–221 | date = May 2012 | pmid = 21620478 | doi = 10.1016/j.jad.2011.04.051 }}</ref>

OCD sometimes manifests without overt compulsions, which may be termed "primarily obsessional OCD." OCD without overt compulsions could, by one estimate, characterize as many as 50–60% of OCD cases.<ref>{{Cite journal | vauthors = Weisman MM |date=May 1998 |title=The cross national epidemiology of obsessive–compulsive disorder |journal=New Developments in Obsessive-Compulsive and Spectrum Disorders |volume=3 |issue=1 |pages=6–9}}</ref>

=== Insight and overvalued ideation ===
The Diagnostic and Statistical Manual of Mental Disorders (DSM-5), identifies a continuum for the level of insight in OCD, ranging from good insight (the least severe) to no insight (the most severe). Good or fair insight is characterized by the acknowledgment that obsessive–compulsive beliefs are not or may not be true, while poor insight, in the middle of the continuum, is characterized by the belief that obsessive–compulsive beliefs are probably true. The absence of insight altogether, in which the individual is completely convinced that their beliefs are true, is also identified as a [[Medicine:Delusion|delusion]]al thought pattern, and occurs in about 4% of people with OCD.<ref>{{Cite web |last=Substance Abuse and Mental Health Services Administration |date=June 2016 |title=Table 3.13, DSM-IV to DSM-5 Obsessive-Compulsive Disorder Comparison |url=https://www.ncbi.nlm.nih.gov/books/NBK519704/table/ch3.t13/ |access-date=11 December 2021 |website=Impact of the DSM-IV to DSM-5 Changes on the National Survey on Drug Use and Health [Internet] |language=en}}</ref><ref name="Sadock">{{Cite book | vauthors = Ruiz P, Sadock B, Sadock V |title=Kaplan and Sadock's Comprehensive Textbook of Psychiatry|publisher=LWW |year=2017 |isbn=978-1-4511-0047-1 |edition=10th}}</ref> When cases of OCD with no insight become severe, affected individuals have an unshakable belief in the reality of their delusions, which can make their cases difficult to differentiate from [[Medicine:Psychosis|psychotic disorders]].<ref name="pmid10755077">{{cite journal | vauthors = O'Dwyer AM, Marks I | title = Obsessive-compulsive disorder and delusions revisited | journal = The British Journal of Psychiatry: The Journal of Mental Science | volume = 176 | issue = 3| pages = 281–4 | date = March 2000 | pmid = 10755077 | doi = 10.1192/bjp.176.3.281 | s2cid = 8365071 | doi-access = free }}</ref>

Some people with OCD exhibit what is known as ''overvalued ideas'', ideas that are abnormal compared to affected individuals' respective cultures, and more treatment-resistant than most negative thoughts and obsessions.<ref name=":8" /> After some discussion, it is possible to convince the individual that their fears are unfounded. It may be more difficult to practice [[Philosophy:Exposure therapy#Obsessive compulsive disorder|exposure and response prevention therapy]] (ERP) on such people, as they may be unwilling to cooperate, at least initially.<ref>{{Cite journal |last=Kozak |first=Michael J. |last2=Foa |first2=Edna B. |date=1994 |title=Obsessions, overvalued ideas, and delusions in obsessive-compulsive disorder |journal=Behaviour Research and Therapy |volume=32 |issue=3 |pages=343–353 |doi=10.1016/0005-7967(94)90132-5 |issn=0005-7967}}</ref> Similar to how insight is identified on a continuum, obsessive-compulsive beliefs are characterized on a spectrum, ranging from obsessive doubt to delusional conviction. In the {{wipe|United States}}, overvalued ideation (OVI) is considered most akin to poor insight—especially when considering belief strength as one of an idea's key identifiers.<ref>{{Cite journal |last=Veale |first=D |date=2002 |title=Over-valuedideas: aconceptualanalysis |url=https://www.veale.co.uk/PDf/Over-valued%20ideas.pdf |journal=Behaviour Research and Therapy |issue=40 |page=1}}</ref> Furthermore, severe and frequent overvalued ideas are considered similar to ''idealized values'', which are so rigidly held by, and so important to affected individuals, that they end up becoming a defining identity.<ref name=":8">{{cite journal | vauthors = Veale D | title = Over-valued ideas: a conceptual analysis | journal = Behaviour Research and Therapy | volume = 40 | issue = 4 | pages = 383–400 | date = April 2002 | pmid = 12002896 | doi = 10.1016/S0005-7967(01)00016-X }}</ref> In adolescent OCD patients, OVI is considered a severe symptom.<ref name=":9">{{cite journal | vauthors = Borda T, Neziroglu F, Taboas W, McKay D, Frenkiel L | title = Overvalued ideation in adolescents with obsessive-compulsive disorder | journal = Psychiatry Research | volume = 255 | pages = 66–71 | date = September 2017 | pmid = 28528243 | doi = 10.1016/j.psychres.2017.05.001 | s2cid = 4627755 }}</ref>

Historically, OVI has been thought to be linked to poorer treatment outcome in patients with OCD, but it is currently considered a poor indicator of prognosis.<ref name=":9" /><ref>{{cite journal | vauthors = Kozak MJ, Foa EB | title = Obsessions, overvalued ideas, and delusions in obsessive-compulsive disorder | journal = Behaviour Research and Therapy | volume = 32 | issue = 3 | pages = 343–353 | date = March 1994 | pmid = 8192634 | doi = 10.1016/0005-7967(94)90132-5 }}</ref> The Overvalued Ideas Scale (OVIS) has been developed as a reliable quantitative method of measuring levels of OVI in patients with OCD, and research has suggested that overvalued ideas are more stable for those with more extreme OVIS scores.<ref>{{cite journal | vauthors = Neziroglu F, McKay D, Yaryura-Tobias JA, Stevens KP, Todaro J | title = The Overvalued Ideas Scale: development, reliability and validity in obsessive-compulsive disorder | journal = Behaviour Research and Therapy | volume = 37 | issue = 9 | pages = 881–902 | date = September 1999 | pmid = 10458051 | doi = 10.1016/S0005-7967(98)00191-0 }}</ref>

=== Cognitive performance ===
Though OCD was once believed to be associated with above-average intelligence, this does not appear to necessarily be the case.<ref>{{cite journal | vauthors = Abramovitch A, Anholt G, Raveh-Gottfried S, Hamo N, Abramowitz JS | title = Meta-Analysis of Intelligence Quotient (IQ) in Obsessive-Compulsive Disorder | journal = Neuropsychology Review | volume = 28 | issue = 1 | pages = 111–120 | date = March 2018 | pmid = 28864868 | doi = 10.1007/s11065-017-9358-0 | s2cid = 4012128 }}</ref> A 2013 review reported that people with OCD may sometimes have mild but wide-ranging [[Medicine:Cognitive deficit|cognitive deficit]]s, most significantly those affecting [[Physics:Spatial memory|spatial memory]] and to a lesser extent with [[Biology:Verbal memory|verbal memory]], [[Social:Verbal fluency test|fluency]], [[Philosophy:Executive functions|executive function]], and processing speed, while auditory attention was not significantly affected.<ref name="shin">{{cite journal | vauthors = Shin NY, Lee TY, Kim E, Kwon JS | title = Cognitive functioning in obsessive-compulsive disorder: a meta-analysis | journal = Psychological Medicine | volume = 44 | issue = 6 | pages = 1121–1130 | date = April 2014 | pmid = 23866289 | doi = 10.1017/S0033291713001803 | s2cid = 28181106 }}</ref> People with OCD show impairment in formulating an organizational strategy for coding information, set-shifting, and motor and [[Cognitive inhibition|cognitive inhibition]].<ref name="Aydin">{{cite journal | vauthors = Çetinay Aydın P, Güleç Öyekçin D | title = [Cognitive functions in patients with obsessive compulsive disorder] | journal = Turk Psikiyatri Dergisi = Turkish Journal of Psychiatry | volume = 24 | issue = 4 | pages = 266–274 | year = 2013 | pmid = 24310094 | doi = 10.5080/u7172 }}</ref>

Specific subtypes of symptom dimensions in OCD have been associated with specific cognitive deficits.<ref>{{cite journal | vauthors = Pauls DL, Abramovitch A, Rauch SL, Geller DA | title = Obsessive-compulsive disorder: an integrative genetic and neurobiological perspective | journal = Nature Reviews. Neuroscience | volume = 15 | issue = 6 | pages = 410–424 | date = June 2014 | pmid = 24840803 | doi = 10.1038/nrn3746 | s2cid = 17781028 }}</ref> For example, the results of one [[Meta-analysis|meta-analysis]] comparing washing and checking symptoms reported that washers outperformed checkers on eight out of ten cognitive tests.<ref>{{cite journal | vauthors = Leopold R, Backenstrass M | title = Neuropsychological differences between obsessive-compulsive washers and checkers: a systematic review and meta-analysis | journal = Journal of Anxiety Disorders | volume = 30 | pages = 48–58 | date = March 2015 | pmid = 25601381 | doi = 10.1016/j.janxdis.2014.12.016 }}</ref> The symptom dimension of contamination and cleaning may be associated with higher scores on tests of inhibition and verbal memory.<ref>{{Cite journal | vauthors = Abramovitch A, Cooperman A |date=April 2015 |title=The cognitive neuropsychology of obsessive-compulsive disorder: A critical review |journal=Journal of Obsessive-Compulsive and Related Disorders |volume=5 |pages=24–36 |doi=10.1016/j.jocrd.2015.01.002}}</ref>

=== Pediatric OCD ===
Approximately 1–2% of children are affected by OCD.<ref>{{cite journal | vauthors = Jones AM, De Nadai AS, Arnold EB, McGuire JF, Lewin AB, Murphy TK, Storch EA | title = Psychometric properties of the obsessive compulsive inventory: child version in children and adolescents with obsessive-compulsive disorder | journal = Child Psychiatry and Human Development | volume = 44 | issue = 1 | pages = 137–151 | date = February 2013 | pmid = 22711294 | doi = 10.1007/s10578-012-0315-0 | s2cid = 27470036 }}</ref> There is a lot of similarity between the clinical presentation of OCD in children and adults, and it is considered a highly familial disorder, with a phenotypic heritability of around 50%.<ref name="Obsessive-Compulsive Disorder in Ch"/><ref>{{cite journal |last1=Blanco-Vieira |first1=Thiago |last2=Radua |first2=Joaquim |last3=Marcelino |first3=Lívia |last4=Bloch |first4=Michael |last5=Mataix-Cols |first5=David |last6=do Rosário |first6=Maria Conceição |title=The genetic epidemiology of obsessive-compulsive disorder: a systematic review and meta-analysis |journal=Translational Psychiatry |date=28 June 2023 |volume=13 |issue=1 |page=230 |doi=10.1038/s41398-023-02433-2|pmid=37380645 |pmc=10307810 |doi-access=free }}</ref> Obsessive–compulsive disorder symptoms tend to develop more frequently in children 10–14 years of age, with males displaying symptoms at an earlier age, and at a more severe level than females.<ref>{{Cite journal | vauthors = Last CG, Strauss CC |year=1989 |title=Obsessive—compulsive disorder in childhood |journal=Journal of Anxiety Disorders |volume=3 |issue=4 |pages=295–302 |doi=10.1016/0887-6185(89)90020-0}}</ref> In children, symptoms can be grouped into at least four types, including sporadic and tic-related OCD.<ref name="Leckman" />

The Children's Yale–Brown Obsessive–Compulsive Scale (CY-BOCS) is the gold standard measure for assessment of pediatric OCD.<ref name="Evidence-Based Assessment of Obsess">{{cite journal |last1=Rapp |first1=Amy M. |last2=Bergman |first2=R. Lindsay |last3=Piacentini |first3=John |last4=Mcguire |first4=Joseph F. |title=Evidence-Based Assessment of Obsessive–Compulsive Disorder |journal=Journal of Central Nervous System Disease |date=January 2016 |volume=8 |pages=13–29 |doi=10.4137/JCNSD.S38359|pmid=27594793 |pmc=4994744 |doi-access=free }}</ref> It follows the Y-BOCS format, but with a Symptom Checklist that is adapted for developmental appropriateness. Insight, avoidance, indecisiveness, responsibility, pervasive slowness, and doubting, are not included in a rating of overall severity. The CY-BOCS has demonstrated good convergent validity with clinician-rated OCD severity, and good to fair discriminant validity from measures of closely related anxiety, depression, and tic severity.<ref name="Evidence-Based Assessment of Obsess"/> The CY-BOCS Total Severity score is an important monitoring tool as it is responsive to pharmacotherapy and psychotherapy.<ref>{{cite journal |last1=McGuire |first1=Joseph F. |last2=Piacentini |first2=John |last3=Lewin |first3=Adam B. |last4=Brennan |first4=Erin A. |last5=Murphy |first5=Tanya K. |last6=Storch |first6=Eric A. |title=A Meta-analysis of Cognitive Behavior Therapy and Medication for Child Obsessive-compulsive Disorder: Moderators of Treatment Efficacy, Response, and Remission: Research Article: Treatment Outcomes and Moderators in Pediatric OCD |journal=Depression and Anxiety |date=August 2015 |volume=32 |issue=8 |pages=580–593 |doi=10.1002/da.22389 |pmid=26130211 |pmc=4515191 }}</ref><ref>{{cite journal |last1=McGuire |first1=Joseph F. |last2=Lewin |first2=Adam B. |last3=Horng |first3=Betty |last4=Murphy |first4=Tanya K. |last5=Storch |first5=Eric A. |title=The Nature, Assessment, and Treatment of Obsessive–Compulsive Disorder |journal=Postgraduate Medicine |date=January 2012 |volume=124 |issue=1 |pages=152–165 |doi=10.3810/pgm.2012.01.2528|pmid=22314125 |s2cid=207639773 }}</ref> Positive treatment response is characterized by 25% reduction in CY-BOCS total score, and diagnostic remission is associated with a 45%-50% reduction in Total Severity score (or a score <15).<ref name="Evidence-Based Assessment of Obsess"/>

CBT is the first line treatment for mild to moderate cases of OCD in children, while medication plus CBT is recommended for moderate to severe cases.<ref>{{cite journal |last1=Watson |first1=Hunna J. |last2=Rees |first2=Clare S. |title=Meta‐analysis of randomized, controlled treatment trials for pediatric obsessive‐compulsive disorder |journal=Journal of Child Psychology and Psychiatry |date=May 2008 |volume=49 |issue=5 |pages=489–498 |doi=10.1111/j.1469-7610.2007.01875.x|pmid=18400058 }}</ref><ref name="Cognitive-Behavior Therapy, Sertral">{{cite journal |title=Cognitive-Behavior Therapy, Sertraline, and Their Combination for Children and Adolescents With Obsessive-Compulsive Disorder: The Pediatric OCD Treatment Study (POTS) Randomized Controlled Trial |journal=JAMA |date=27 October 2004 |volume=292 |issue=16 |pages=1969–1976 |doi=10.1001/jama.292.16.1969|pmid=15507582 |author1=Pediatric OCD Treatment Study (POTS) Team }}</ref><ref>{{cite journal |last1=Geller |first1=Daniel A. |last2=Biederman |first2=Joseph |last3=Stewart |first3=S. Evelyn |last4=Mullin |first4=Benjamin |last5=Martin |first5=Andrés |last6=Spencer |first6=Thomas |last7=Faraone |first7=Stephen V. |title=Which SSRI? A Meta-Analysis of Pharmacotherapy Trials in Pediatric Obsessive-Compulsive Disorder |journal=American Journal of Psychiatry |date=November 2003 |volume=160 |issue=11 |pages=1919–1928 |doi=10.1176/appi.ajp.160.11.1919|pmid=14594734 |s2cid=8711232 }}</ref> Serotonin reuptake inhibitors (SRIs) are first-line medications for OCD in children with established AACAP guidelines for dosing.<ref name="Practice Parameter for the Assessme">{{cite journal |last1=Geller |first1=Daniel A. |last2=March |first2=John |title=Practice Parameter for the Assessment and Treatment of Children and Adolescents With Obsessive-Compulsive Disorder |journal=Journal of the American Academy of Child & Adolescent Psychiatry |date=January 2012 |volume=51 |issue=1 |pages=98–113 |doi=10.1016/j.jaac.2011.09.019|pmid=22176943 |doi-access=free }}</ref>

=== Associated conditions ===
People with OCD may be diagnosed with other conditions as well, such as obsessive–compulsive personality disorder, major depressive disorder, [[Medicine:Bipolar disorder|bipolar disorder]], [[Medicine:Generalized anxiety disorder|generalized anxiety disorder]], [[Medicine:Anorexia nervosa|anorexia nervosa]], [[Medicine:Social anxiety disorder|social anxiety disorder]], [[Medicine:Bulimia nervosa|bulimia nervosa]], [[Medicine:Tourette syndrome|Tourette syndrome]], [[Medicine:Transformation obsession|transformation obsession]], ASD, ADHD, dermatillomania, [[Medicine:Body dysmorphic disorder|body dysmorphic disorder]], and [[Medicine:Trichotillomania|trichotillomania]].<ref>{{cite journal | vauthors = Chen YW, Dilsaver SC | title = Comorbidity for obsessive-compulsive disorder in bipolar and unipolar disorders | journal = Psychiatry Research | volume = 59 | issue = 1–2 | pages = 57–64 | date = November 1995 | pmid = 8771221 | doi = 10.1016/0165-1781(95)02752-1 | s2cid = 2782199 }}</ref> More than 50% of people with OCD experience suicidal tendencies, and 15% have attempted [[Medicine:Suicide|suicide]].<ref name="Fenske_2009" /> Depression, anxiety, and prior suicide attempts increase the risk of future suicide attempts.<ref>{{cite journal | vauthors = Angelakis I, Gooding P, Tarrier N, Panagioti M | title = Suicidality in obsessive compulsive disorder (OCD): a systematic review and meta-analysis | journal = Clinical Psychology Review | volume = 39 | pages = 1–15 | date = July 2015 | pmid = 25875222 | doi = 10.1016/j.cpr.2015.03.002 }}</ref>

It has been found that between 18 and 34% of females currently experiencing OCD scored positively on an inventory measuring disordered eating.<ref name=":12">{{cite journal | vauthors = Bang L, Kristensen UB, Wisting L, Stedal K, Garte M, Minde Å, Rø Ø | title = Presence of eating disorder symptoms in patients with obsessive-compulsive disorder | journal = BMC Psychiatry | volume = 20 | issue = 1 | page = 36 | date = January 2020 | pmid = 32000754 | pmc = 6993325 | doi = 10.1186/s12888-020-2457-0 | doi-access = free }}</ref> Another study found that 7% are likely to have an eating disorder,<ref name=":12" /> while another found that fewer than 5% of males have OCD and an eating disorder.<ref>{{cite journal |vauthors=Tyagi H, Patel R, Rughooputh F, Abrahams H, Watson AJ, Drummond L |title=Comparative Prevalence of Eating Disorders in Obsessive-Compulsive Disorder and Other Anxiety Disorders |journal=Psychiatry Journal |year=2015 |volume=2015 |page=186927 |publisher=Hindawi Psychiatry Journal |doi=10.1155/2015/186927 |pmid=26366407 |pmc=4561118 |doi-access=free }}</ref>

Individuals with OCD have also been found to be affected by [[Medicine:Delayed sleep phase disorder|delayed sleep phase disorder]] at a substantially higher rate than the general public.<ref name="Turner 2007">{{cite journal | vauthors = Turner J, Drummond LM, Mukhopadhyay S, Ghodse H, White S, Pillay A, Fineberg NA | title = A prospective study of delayed sleep phase syndrome in patients with severe resistant obsessive-compulsive disorder | journal = World Psychiatry | volume = 6 | issue = 2 | pages = 108–111 | date = June 2007 | pmid = 18235868 | pmc = 2219909 }}</ref><ref name="Paterson2013"/> Moreover, severe OCD symptoms are consistently associated with greater sleep disturbance. Reduced total sleep time and sleep efficiency have been observed in people with OCD, with delayed sleep onset and offset.<ref name="Paterson2013">{{cite journal | vauthors = Paterson JL, Reynolds AC, Ferguson SA, Dawson D | title = Sleep and obsessive-compulsive disorder (OCD) | journal = Sleep Medicine Reviews | volume = 17 | issue = 6 | pages = 465–474 | date = December 2013 | pmid = 23499210 | doi = 10.1016/j.smrv.2012.12.002 }}</ref>

Some research has demonstrated a link between [[Medicine:Addiction|drug addiction]] and OCD. For example, there is a higher risk of drug addiction among those with any anxiety disorder, likely as a way of [[Social:Coping (psychology)|coping]] with the heightened levels of anxiety. However, drug addiction among people with OCD may be a compulsive behavior. Depression is also extremely prevalent among people with OCD. One explanation for the high depression rate among OCD populations was posited by Mineka, Watson, and Clark (1998), who explained that people with OCD, or any other anxiety disorder, may feel "out of control".<ref name="comorbidity">{{cite journal | vauthors = Mineka S, Watson D, Clark LA | title = Comorbidity of anxiety and unipolar mood disorders | journal = Annual Review of Psychology | volume = 49 | pages = 377–412 | year = 1998 | pmid = 9496627 | doi = 10.1146/annurev.psych.49.1.377 | s2cid = 14546782 }}</ref>

Someone exhibiting OCD signs does not necessarily have OCD. Behaviors that present as obsessive–compulsive can also be found in a number of other conditions, including [[Medicine:Obsessive–compulsive personality disorder|obsessive–compulsive personality disorder]] (OCPD), autism spectrum disorder (ASD), or disorders in which [[Medicine:Perseveration|perseveration]] is a possible feature (ADHD, PTSD, bodily disorders, or [[Biology:Stereotypy|stereotyped behaviors]]).<ref name="differential">[http://emedicine.medscape.com/article/1826591-differential Pediatric Obsessive-Compulsive Disorder Differential Diagnoses] {{webarchive|url=https://web.archive.org/web/20120917123925/http://emedicine.medscape.com/article/1826591-differential |date=17 September 2012 }} – 2012</ref> Some cases of OCD present symptoms typically associated with Tourette syndrome, such as compulsions that may appear to resemble motor tics; this has been termed ''tic-related OCD'' or ''Tourettic OCD''.<ref name="10.1176/appi.neuropsych.21.1.59">{{cite journal | vauthors = Mansueto CS, Keuler DJ | title = Tic or compulsion?: it's Tourettic OCD | journal = Behavior Modification | volume = 29 | issue = 5 | pages = 784–799 | date = September 2005 | pmid = 16046664 | doi = 10.1177/0145445505279261 | s2cid = 146592937 }}</ref><ref name="OCD and T">{{Cite web |title=OCD and Tourette Syndrome: Re-examining the Relationship |url=http://www.ocfoundation.org/eo_ts.aspx |url-status=live |archive-url=https://web.archive.org/web/20131101085624/http://www.ocfoundation.org/eo_ts.aspx |archive-date=1 November 2013 |access-date=30 October 2013 |publisher=International OCD Foundation}}</ref>

OCD frequently occurs [[Medicine:Comorbidity|comorbidly]] with both [[Medicine:Bipolar disorder|bipolar disorder]] and major depressive disorder. Between 60 and 80% of those with OCD experience a major depressive episode in their lifetime. Comorbidity rates have been reported at between 19 and 90%, as a result of methodological differences. Between 9–35% of those with bipolar disorder also have OCD, compared to 1–2% in the general population. About 50% of those with OCD experience [[Medicine:Cyclothymia|cyclothymic]] traits or [[Medicine:Hypomania|hypomanic]] episodes. OCD is also associated with anxiety disorders. Lifetime comorbidity for OCD has been reported at 22% for specific phobia, 18% for [[Medicine:Social anxiety disorder|social anxiety disorder]], 12% for [[Medicine:Panic disorder|panic disorder]], and 30% for [[Medicine:Generalized anxiety disorder|generalized anxiety disorder]]. The comorbidity rate for OCD and ADHD has been reported to be as high as 51%.<ref>{{cite journal | vauthors = Pallanti S, Grassi G, Sarrecchia ED, Cantisani A, Pellegrini M | title = Obsessive-compulsive disorder comorbidity: clinical assessment and therapeutic implications | journal = Frontiers in Psychiatry | volume = 2 | page = 70 | date = 2011 | pmid = 22203806 | pmc = 3243905 | doi = 10.3389/fpsyt.2011.00070 | doi-access = free }}</ref>

== Causes ==
The cause of OCD is unknown.<ref name="NIH20152" /> Both environmental and genetic factors are believed to play a role. Risk factors include a history of adverse childhood experiences or other stress-inducing events.<ref name="DSM52" /><ref>{{cite journal | vauthors = Ou W, Li Z, Zheng Q, Chen W, Liu J, Liu B, Zhang Y | title = Association Between Childhood Maltreatment and Symptoms of Obsessive-Compulsive Disorder: A Meta-Analysis | journal = Frontiers in Psychiatry | volume = 11 | page = 612586 | date = 2021-01-20 | pmid = 33551875 | pmc = 7854900 | doi = 10.3389/fpsyt.2020.612586 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Gu W, Zhao Q, Yuan C, Yi Z, Zhao M, Wang Z | title = Impact of adverse childhood experiences on the symptom severity of different mental disorders: a cross-diagnostic study | journal = General Psychiatry | volume = 35 | issue = 2 | pages = e100741 | date = 2022 | pmid = 35572774 | pmc = 9036421 | doi = 10.1136/gpsych-2021-100741 }}</ref>

=== Drug-induced OCD ===
Some medications and other drugs, such as [[Chemistry:Methamphetamine|methamphetamine]] or [[Biology:Cocaine|cocaine]], can induce obsessive-compulsive disorder (OCD) in people without previous symptoms.<ref>{{Cite book |title=Diagnostic and statistical manual of mental disorders: DSM-5. |date=2013 |publisher=American Psychiatric Association |isbn=978-0-89042-554-1 |edition=5th |location=Arlington, VA |oclc=830807378}}</ref>

Some [[Chemistry:Atypical antipsychotic|atypical antipsychotic]]s (second-generation antipsychotics) such as [[Chemistry:Olanzapine|olanzapine]] (Zyprexa) and [[Chemistry:Clozapine|clozapine]] (Clozaril) can induce OCD in people, particularly individuals with [[Medicine:Schizophrenia|schizophrenia]].<ref>{{cite journal | vauthors = Alevizos B, Papageorgiou C, Christodoulou GN | title = Obsessive-compulsive symptoms with olanzapine | journal = The International Journal of Neuropsychopharmacology | volume = 7 | issue = 3 | pages = 375–377 | date = September 2004 | pmid = 15231024 | doi = 10.1017/S1461145704004456 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Kulkarni G, Narayanaswamy JC, Math SB | title = Olanzapine induced de-novo obsessive compulsive disorder in a patient with schizophrenia | journal = Indian Journal of Pharmacology | volume = 44 | issue = 5 | pages = 649–650 | date = 1 January 2012 | pmid = 23112432 | pmc = 3480803 | doi = 10.4103/0253-7613.100406 | doi-access = free }}</ref><ref>{{cite journal | vauthors = Lykouras L, Zervas IM, Gournellis R, Malliori M, Rabavilas A | title = Olanzapine and obsessive-compulsive symptoms | journal = European Neuropsychopharmacology | volume = 10 | issue = 5 | pages = 385–387 | date = September 2000 | pmid = 10974610 | doi = 10.1016/s0924-977x(00)00096-1 | s2cid = 276209 }}</ref><ref>{{cite journal | vauthors = Schirmbeck F, Zink M | title = Clozapine-induced obsessive-compulsive symptoms in schizophrenia: a critical review | journal = Current Neuropharmacology | volume = 10 | issue = 1 | pages = 88–95 | date = March 2012 | pmid = 22942882 | pmc = 3286851 | doi = 10.2174/157015912799362724 }}</ref>

=== Genetics ===
There appear to be some [[Biology:Genetics|genetic]] components of OCD causation, with identical twins more often affected than fraternal twins.<ref name="DSM52" /> Furthermore, individuals with OCD are more likely to have first-degree family members exhibiting the same disorders than matched controls. In cases in which OCD develops during childhood, there is a much stronger familial link in the disorder than with cases in which OCD develops later in adulthood. In general, genetic factors account for 45–65% of the variability in OCD symptoms in children diagnosed with the disorder.<ref name="pmid19665647">{{cite journal | vauthors = Abramowitz JS, Taylor S, McKay D | title = Obsessive-compulsive disorder | journal = Lancet | volume = 374 | issue = 9688 | pages = 491–499 | date = August 2009 | pmid = 19665647 | doi = 10.1016/S0140-6736(09)60240-3 | s2cid = 203833429 }}</ref> A 2007 study found evidence supporting the possibility of a heritable risk for OCD.<ref name="Menzies et al, 2007">{{cite journal | vauthors = Menzies L, Achard S, Chamberlain SR, Fineberg N, Chen CH, del Campo N, Sahakian BJ, Robbins TW, Bullmore E | display-authors = 6 | title = Neurocognitive endophenotypes of obsessive-compulsive disorder | journal = Brain | volume = 130 | issue = Pt 12 | pages = 3223–3236 | date = December 2007 | pmid = 17855376 | doi = 10.1093/brain/awm205 | doi-access = free }}</ref>

Research has found there to be a genetic correlation between anorexia nervosa and OCD, suggesting a strong etiology.<ref name=":13">{{cite journal | vauthors = Lee EB, Barney JL, Twohig MP, Lensegrav-Benson T, Quakenbush B | title = Obsessive compulsive disorder and thought action fusion: Relationships with eating disorder outcomes | journal = Eating Behaviors | volume = 37 | page = 101386 | date = April 2020 | pmid = 32388080 | doi = 10.1016/j.eatbeh.2020.101386 | s2cid = 218585620 }}</ref><ref>{{cite journal | vauthors = Levinson CA, Brosof LC, Ram SS, Pruitt A, Russell S, Lenze EJ | title = Obsessions are strongly related to eating disorder symptoms in anorexia nervosa and atypical anorexia nervosa | journal = Eating Behaviors | volume = 34 | page = 101298 | date = August 2019 | pmid = 31176948 | pmc = 6708491 | doi = 10.1016/j.eatbeh.2019.05.001 }}</ref><ref>{{cite journal | vauthors = Meier M, Kossakowski JJ, Jones PJ, Kay B, Riemann BC, McNally RJ | title = Obsessive-compulsive symptoms in eating disorders: A network investigation | journal = The International Journal of Eating Disorders | volume = 53 | issue = 3 | pages = 362–371 | date = March 2020 | pmid = 31749199 | doi = 10.1002/eat.23196 | s2cid = 208214719 }}</ref> First and second hand relatives of probands with OCD have a greater risk of developing anorexia nervosa as genetic relatedness increases.<ref name=":13" />

A [[Biology:Mutation|mutation]] has been found in the human [[Chemistry:Serotonin|serotonin]] transporter gene hSERT in unrelated families with OCD.<ref name="pmid14593431">{{cite journal | vauthors = Ozaki N, Goldman D, Kaye WH, Plotnicov K, Greenberg BD, Lappalainen J, Rudnick G, Murphy DL | display-authors = 6 | title = Serotonin transporter missense mutation associated with a complex neuropsychiatric phenotype | journal = Molecular Psychiatry | volume = 8 | issue = 11 | pages = 933–936 | date = November 2003 | pmid = 14593431 | doi = 10.1038/sj.mp.4001365 | s2cid = 2171955 | doi-access =  }}</ref>

A [[Systematic review|systematic review]] found that while neither [[Biology:Allele|allele]] was associated with OCD overall, in [[Biology:Caucasian race|Caucasians]], the L allele was associated with OCD.<ref>{{cite journal | vauthors = Bloch MH, Landeros-Weisenberger A, Sen S, Dombrowski P, Kelmendi B, Coric V, Pittenger C, Leckman JF | display-authors = 6 | title = Association of the serotonin transporter polymorphism and obsessive-compulsive disorder: systematic review | journal = American Journal of Medical Genetics. Part B, Neuropsychiatric Genetics | volume = 147B | issue = 6 | pages = 850–858 | date = September 2008 | pmid = 18186076 | doi = 10.1002/ajmg.b.30699 | s2cid = 23223447 }}</ref> Another meta-analysis observed an increased risk in those with the [[Biology:Zygosity|homozygous]] S allele, but found the LS [[Biology:Genotype|genotype]] to be inversely associated with OCD.<ref>{{cite journal | vauthors = Lin PY | title = Meta-analysis of the association of serotonin transporter gene polymorphism with obsessive-compulsive disorder | journal = Progress in Neuro-Psychopharmacology & Biological Psychiatry | volume = 31 | issue = 3 | pages = 683–689 | date = April 2007 | pmid = 17291658 | doi = 10.1016/j.pnpbp.2006.12.024 | s2cid = 40442832 }}</ref>

A [[Biology:Genome|genome]]-wide association study found OCD to be linked with [[Biology:Single-nucleotide polymorphism|single-nucleotide polymorphism]]s (SNPs) near BTBD3, and two SNPs in [[Biology:DLGAP1|DLGAP1]] in a trio-based analysis, but no SNP reached significance when analyzed with case-control data.<ref>{{cite journal | vauthors = Stewart SE, Yu D, Scharf JM, Neale BM, Fagerness JA, Mathews CA, Arnold PD, Evans PD, Gamazon ER, Davis LK, Osiecki L, McGrath L, Haddad S, Crane J, Hezel D, Illman C, Mayerfeld C, Konkashbaev A, Liu C, Pluzhnikov A, Tikhomirov A, Edlund CK, Rauch SL, Moessner R, Falkai P, Maier W, Ruhrmann S, Grabe HJ, Lennertz L, Wagner M, Bellodi L, Cavallini MC, Richter MA, Cook EH, Kennedy JL, Rosenberg D, Stein DJ, Hemmings SM, Lochner C, Azzam A, Chavira DA, Fournier E, Garrido H, Sheppard B, Umaña P, Murphy DL, Wendland JR, Veenstra-VanderWeele J, Denys D, Blom R, Deforce D, Van Nieuwerburgh F, Westenberg HG, Walitza S, Egberts K, Renner T, Miguel EC, Cappi C, Hounie AG, Conceição do Rosário M, Sampaio AS, Vallada H, Nicolini H, Lanzagorta N, Camarena B, Delorme R, Leboyer M, Pato CN, Pato MT, Voyiaziakis E, Heutink P, Cath DC, Posthuma D, Smit JH, Samuels J, Bienvenu OJ, Cullen B, Fyer AJ, Grados MA, Greenberg BD, McCracken JT, Riddle MA, Wang Y, Coric V, Leckman JF, Bloch M, Pittenger C, Eapen V, Black DW, Ophoff RA, Strengman E, Cusi D, Turiel M, Frau F, Macciardi F, Gibbs JR, Cookson MR, Singleton A, Hardy J, Crenshaw AT, Parkin MA, Mirel DB, Conti DV, Purcell S, Nestadt G, Hanna GL, Jenike MA, Knowles JA, Cox N, Pauls DL | display-authors = 6 | title = Genome-wide association study of obsessive-compulsive disorder | journal = Molecular Psychiatry | volume = 18 | issue = 7 | pages = 788–798 | date = July 2013 | pmid = 22889921 | pmc = 4218751 | doi = 10.1038/mp.2012.85 }}</ref>

One meta-analysis found a small but significant association between a polymorphism in [[Biology:SLC1A1|SLC1A1]] and OCD.<ref>{{cite journal | vauthors = Stewart SE, Mayerfeld C, Arnold PD, Crane JR, O'Dushlaine C, Fagerness JA, Yu D, Scharf JM, Chan E, Kassam F, Moya PR, Wendland JR, Delorme R, Richter MA, Kennedy JL, Veenstra-VanderWeele J, Samuels J, Greenberg BD, McCracken JT, Knowles JA, Fyer AJ, Rauch SL, Riddle MA, Grados MA, Bienvenu OJ, Cullen B, Wang Y, Shugart YY, Piacentini J, Rasmussen S, Nestadt G, Murphy DL, Jenike MA, Cook EH, Pauls DL, Hanna GL, Mathews CA | display-authors = 6 | title = Meta-analysis of association between obsessive-compulsive disorder and the 3' region of neuronal glutamate transporter gene SLC1A1 | journal = American Journal of Medical Genetics. Part B, Neuropsychiatric Genetics | volume = 162B | issue = 4 | pages = 367–379 | date = June 2013 | pmid = 23606572 | doi = 10.1002/ajmg.b.32137 | hdl-access = free | s2cid = 20929721 | hdl = 2027.42/98412 }}</ref>

The relationship between OCD and [[Biology:Catechol-O-methyltransferase|Catechol-O-methyltransferase]] (COMT) has been inconsistent, with one meta-analysis reporting a significant association, albeit only in men, and another meta analysis reporting no association.<ref>{{cite journal | vauthors = Pooley EC, Fineberg N, Harrison PJ | title = The met(158) allele of catechol-O-methyltransferase (COMT) is associated with obsessive-compulsive disorder in men: case-control study and meta-analysis | journal = Molecular Psychiatry | volume = 12 | issue = 6 | pages = 556–561 | date = June 2007 | pmid = 17264842 | doi = 10.1038/sj.mp.4001951 | s2cid = 12532617 | doi-access =  }}</ref><ref>{{cite journal | vauthors = Azzam A, Mathews CA | title = Meta-analysis of the association between the catecholamine-O-methyl-transferase gene and obsessive-compulsive disorder | journal = American Journal of Medical Genetics. Part B, Neuropsychiatric Genetics | volume = 123B | issue = 1 | pages = 64–69 | date = November 2003 | pmid = 14582147 | doi = 10.1002/ajmg.b.20013 | s2cid = 42840925 }}</ref>

It has been postulated by [[Philosophy:Evolutionary psychology|evolutionary psychologists]] that moderate versions of compulsive behavior may have had evolutionary advantages. Examples would be moderate constant checking of hygiene, the hearth, or the environment for enemies. Similarly, [[Philosophy:Hoarding|hoarding]] may have had evolutionary advantages. In this view, OCD may be the extreme statistical tail of such behaviors, possibly the result of a high number of predisposing genes.<ref>{{cite journal | vauthors = Bracha HS | title = Human brain evolution and the "Neuroevolutionary Time-depth Principle:" Implications for the Reclassification of fear-circuitry-related traits in DSM-V and for studying resilience to warzone-related posttraumatic stress disorder | journal = Progress in Neuro-Psychopharmacology & Biological Psychiatry | volume = 30 | issue = 5 | pages = 827–853 | date = July 2006 | pmid = 16563589 | pmc = 7130737 | doi = 10.1016/j.pnpbp.2006.01.008 }}</ref>

=== Brain structure and functioning ===
[[Medicine:Medical imaging|Imaging]] studies have shown differences in the [[Biology:Frontal lobe|frontal cortex]] and [[Biology:Cerebral cortex|subcortical]] structures of the brain in patients with OCD. There appears to be a connection between the OCD symptoms and abnormalities in certain areas of the brain, but such a connection is not clear.<ref name=":10">{{Cite web |title=Obsessive-Compulsive Disorder |url=https://www.nimh.nih.gov/health/topics/obsessive-compulsive-disorder-ocd |access-date=2022-03-23 |website=National Institute of Mental Health (NIMH) |language=en}}</ref> Some people with OCD have areas of unusually high activity in their brain, or low levels of the chemical [[Chemistry:Serotonin|serotonin]],<ref name=":11">{{Cite web |date=2021-02-16 |title=Overview - Obsessive compulsive disorder (OCD) |url=https://www.nhs.uk/mental-health/conditions/obsessive-compulsive-disorder-ocd/overview/ |access-date=2022-03-23 |website=nhs.uk |language=en}}</ref> which is a [[Biology:Neurotransmitter|neurotransmitter]] that some nerve cells use to communicate with each other,<ref>{{Cite web |title=Obsessive-compulsive Disorder {{!}} NAMI: National Alliance on Mental Illness |url=https://www.nami.org/About-Mental-Illness/Mental-Health-Conditions/Obsessive-compulsive-Disorder |access-date=2022-03-23 |website=www.nami.org}}</ref> and is thought to be involved in regulating many functions, influencing emotions, mood, memory, and sleep.<ref name="How SSRIs work {{!}} OCD-UK">{{Cite web |title=How SSRIs work {{!}} OCD-UK |url=https://www.ocduk.org/overcoming-ocd/medication/how-ssri-work/ |access-date=2022-03-23 |language=en-GB}}</ref>

=== Autoimmune ===
A controversial hypothesis is that some cases of rapid onset of OCD in children and adolescents may be caused by a syndrome connected to Group A streptococcal infections (GABHS), known as pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections ([[Medicine:PANDAS|PANDAS]]).<ref name="Sigra2018">{{cite journal | vauthors = Sigra S, Hesselmark E, Bejerot S | title = Treatment of PANDAS and PANS: a systematic review | journal = Neuroscience and Biobehavioral Reviews | volume = 86 | pages = 51–65 | date = March 2018 | pmid = 29309797 | doi = 10.1016/j.neubiorev.2018.01.001 | s2cid = 40827012 | doi-access = free }}</ref><ref name="Wilbur2019">{{cite journal | vauthors = Wilbur C, Bitnun A, Kronenberg S, Laxer RM, Levy DM, Logan WJ, Shouldice M, Yeh EA | display-authors = 6 | title = PANDAS/PANS in childhood: Controversies and evidence | journal = Paediatrics & Child Health | volume = 24 | issue = 2 | pages = 85–91 | date = May 2019 | pmid = 30996598 | pmc = 6462125 | doi = 10.1093/pch/pxy145 }}</ref><ref name="Boileau2011">{{cite journal | vauthors = Boileau B | title = A review of obsessive-compulsive disorder in children and adolescents | journal = Dialogues in Clinical Neuroscience | volume = 13 | issue = 4 | pages = 401–411 | year = 2011 | pmid = 22275846 | pmc = 3263388 | doi = 10.31887/DCNS.2011.13.4/bboileau }}</ref> OCD and tic disorders are hypothesized to arise in a subset of children as a result of a post-[[Biology:Streptococcus|streptococcal]] autoimmune process.<ref name= Dale2017/><ref name= Marazziti2018/><ref name= Zibordi2018/> The PANDAS hypothesis is unconfirmed and unsupported by data, and two new categories have been proposed: [[Medicine:PANDAS|PANS]] (pediatric acute-onset neuropsychiatric syndrome) and CANS (childhood acute neuropsychiatric syndrome).<ref name= Marazziti2018/><ref name= Zibordi2018/> The CANS and PANS hypotheses include different possible mechanisms underlying acute-onset neuropsychiatric conditions, but do not exclude GABHS infections as a cause in a subset of individuals.<ref name= Marazziti2018/><ref name= Zibordi2018/> PANDAS, PANS, and CANS are the focus of clinical and laboratory research, but remain unproven.<ref name="Dale2017">{{cite journal | vauthors = Dale RC | title = Tics and Tourette: a clinical, pathophysiological and etiological review | journal = Current Opinion in Pediatrics | volume = 29 | issue = 6 | pages = 665–673 | date = December 2017 | pmid = 28915150 | doi = 10.1097/MOP.0000000000000546 | type = Review | s2cid = 13654194 }}</ref><ref name="Marazziti2018">{{cite journal | vauthors = Marazziti D, Mucci F, Fontenelle LF | title = Immune system and obsessive-compulsive disorder | journal = Psychoneuroendocrinology | volume = 93 | pages = 39–44 | date = July 2018 | pmid = 29689421 | doi = 10.1016/j.psyneuen.2018.04.013 | s2cid = 13681480 | type = Review }}</ref><ref name="Zibordi2018">{{cite journal | vauthors = Zibordi F, Zorzi G, Carecchio M, Nardocci N | title = CANS: Childhood acute neuropsychiatric syndromes | journal = European Journal of Paediatric Neurology | volume = 22 | issue = 2 | pages = 316–320 | date = March 2018 | pmid = 29398245 | doi = 10.1016/j.ejpn.2018.01.011 | type = Review }}</ref> Whether PANDAS is a distinct entity differing from other cases of tic disorders or OCD is debated.<ref name="Shulman2009">{{cite journal | vauthors = Shulman ST | title = Pediatric autoimmune neuropsychiatric disorders associated with streptococci (PANDAS): update | journal = Current Opinion in Pediatrics | volume = 21 | issue = 1 | pages = 127–130 | date = February 2009 | pmid = 19242249 | doi = 10.1097/MOP.0b013e32831db2c4 | quote = Despite continued research in the field, the relationship between GAS and specific neuropsychiatric disorders (PANDAS) remains elusive. | s2cid = 37434919 }}</ref><ref name="Maia2008">{{cite journal | vauthors = Maia TV, Cooney RE, Peterson BS | title = The neural bases of obsessive-compulsive disorder in children and adults | journal = Development and Psychopathology | volume = 20 | issue = 4 | pages = 1251–1283 | year = 2008 | pmid = 18838041 | pmc = 3079445 | doi = 10.1017/S0954579408000606 }}</ref><ref name="Robertson2011">{{cite journal | vauthors = Robertson MM | title = Gilles de la Tourette syndrome: the complexities of phenotype and treatment | journal = British Journal of Hospital Medicine | volume = 72 | issue = 2 | pages = 100–107 | date = February 2011 | pmid = 21378617 | doi = 10.12968/hmed.2011.72.2.100 }}</ref><ref name="Singer2011">{{Cite book | vauthors = Singer HS |title=Hyperkinetic Movement Disorders |year=2011 |isbn=978-0-444-52014-2 |series=Handbook of Clinical Neurology |volume=100 |pages=641–57 |chapter=Tourette syndrome and other tic disorders |doi=10.1016/B978-0-444-52014-2.00046-X |pmid=21496613}}</ref>

A review of studies examining anti-basal ganglia [[Biology:Antibody|antibodies]] in OCD found an increased risk of having anti-basal ganglia antibodies in those with OCD versus the general population.<ref>{{cite journal |vauthors=Pearlman DM, Vora HS, Marquis BG, Najjar S, Dudley LA | title = Anti-basal ganglia antibodies in primary obsessive-compulsive disorder: systematic review and meta-analysis | journal = The British Journal of Psychiatry | volume = 205 | issue = 1 | pages = 8–16 | date = July 2014 | pmid = 24986387 | doi = 10.1192/bjp.bp.113.137018 | doi-access = free }}</ref>

=== Environment ===
OCD may be more common in people who have been bullied, abused, or neglected, and it sometimes starts after a significant life event, such as childbirth or bereavement.<ref name=":11" /> It has been reported in some studies that there is a connection between [[Medicine:Childhood trauma|childhood trauma]] and obsessive-compulsive symptoms. More research is needed to understand this relationship better.<ref name=":10" />

== Mechanisms ==

=== Neuroimaging ===
[[File:OCD - Obsessive–compulsive disorder.jpg|thumb|upright=1.35|Some parts of the brain showing abnormal activity in OCD: Orbitofrontal cortex integrates rewards, emotions, and behaviors; anterior cingulate cortex is involved in error detection; amygdala is involved in emotional interpretation of reward]]

Functional neuroimaging during symptom provocation has observed abnormal activity in the [[Biology:Orbitofrontal cortex|orbitofrontal cortex]] (OFC), left [[Biology:Dorsolateral prefrontal cortex|dorsolateral prefrontal cortex]] (dlPFC), right [[Biology:Premotor cortex|premotor cortex]], left superior [[Biology:Superior temporal gyrus|temporal gyrus]], globus pallidus externus, [[Biology:Hippocampus|hippocampus]], and right [[Biology:Uncus|uncus]]. Weaker foci of abnormal activity were found in the left [[Biology:Caudate nucleus|caudate]], [[Biology:Posterior cingulate cortex|posterior cingulate cortex]], and [[Biology:Superior parietal lobule|superior parietal lobule]].<ref>{{cite journal | vauthors = Rotge JY, Guehl D, Dilharreguy B, Cuny E, Tignol J, Bioulac B, Allard M, Burbaud P, Aouizerate B | display-authors = 6 | title = Provocation of obsessive-compulsive symptoms: a quantitative voxel-based meta-analysis of functional neuroimaging studies | journal = Journal of Psychiatry & Neuroscience | volume = 33 | issue = 5 | pages = 405–412 | date = September 2008 | pmid = 18787662 | pmc = 2527721 }}</ref> However, an older meta-analysis of functional neuroimaging in OCD reported that the only consistent functional neuroimaging finding was increased activity in the [[Biology:Orbital gyri|orbital gyrus]] and head of the [[Biology:Caudate nucleus|caudate nucleus]], while [[Biology:Anterior cingulate cortex|anterior cingulate cortex]] (ACC) activation abnormalities were too inconsistent.<ref>{{cite journal | vauthors = Whiteside SP, Port JD, Abramowitz JS | title = A meta-analysis of functional neuroimaging in obsessive-compulsive disorder | journal = Psychiatry Research | volume = 132 | issue = 1 | pages = 69–79 | date = November 2004 | pmid = 15546704 | doi = 10.1016/j.pscychresns.2004.07.001 | s2cid = 9941792 }}</ref>

A meta-analysis comparing affective and nonaffective tasks observed differences with controls in regions implicated in [[Salience (neuroscience)|salience]], habit, goal-directed behavior, self-referential thinking, and cognitive control. For nonaffective tasks, hyperactivity was observed in the [[Biology:Insular cortex|insula]], ACC, and head of the [[Biology:Caudate nucleus|caudate]]/[[Biology:Putamen|putamen]], while hypoactivity was observed in the medial prefrontal cortex (mPFC) and posterior caudate. Affective tasks were observed to relate to increased activation in the [[Biology:Precuneus|precuneus]] and [[Biology:Posterior cingulate cortex|posterior cingulate cortex]], while decreased activation was found in the [[Biology:Globus pallidus|pallidum]], ventral anterior thalamus, and posterior caudate.<ref>{{cite journal | vauthors = Rasgon A, Lee WH, Leibu E, Laird A, Glahn D, Goodman W, Frangou S | title = Neural correlates of affective and non-affective cognition in obsessive compulsive disorder: A meta-analysis of functional imaging studies | journal = European Psychiatry | volume = 46 | pages = 25–32 | date = October 2017 | pmid = 28992533 | doi = 10.1016/j.eurpsy.2017.08.001 | s2cid = 5368803 }}</ref> The involvement of the [[Biology:Cortico-basal ganglia-thalamo-cortical loop|cortico-striato-thalamo-cortical]] loop in OCD, as well as the high rates of comorbidity between OCD and ADHD, have led some to draw a link in their mechanism. Observed similarities include dysfunction of the [[Biology:Anterior cingulate cortex|anterior cingulate cortex]] and [[Biology:Prefrontal cortex|prefrontal cortex]], as well as shared deficits in executive functions.<ref>{{cite journal | vauthors = Brem S, Grünblatt E, Drechsler R, Riederer P, Walitza S | title = The neurobiological link between OCD and ADHD | journal = Attention Deficit and Hyperactivity Disorders | volume = 6 | issue = 3 | pages = 175–202 | date = September 2014 | pmid = 25017045 | pmc = 4148591 | doi = 10.1007/s12402-014-0146-x }}</ref> The involvement of the orbitofrontal cortex and dorsolateral prefrontal cortex in OCD is shared with [[Medicine:Bipolar disorder|bipolar disorder]], and may explain the high degree of comorbidity.<ref name="radua2010" /> Decreased volumes of the dorsolateral prefrontal cortex related to executive function has also been observed in OCD.<ref>{{cite journal | vauthors = Piras F, Piras F, Chiapponi C, Girardi P, Caltagirone C, Spalletta G | title = Widespread structural brain changes in OCD: a systematic review of voxel-based morphometry studies | journal = Cortex; A Journal Devoted to the Study of the Nervous System and Behavior | volume = 62 | pages = 89–108 | date = January 2015 | pmid = 23582297 | doi = 10.1016/j.cortex.2013.01.016 | s2cid = 206984783 }}</ref>

People with OCD evince increased [[Biology:Grey matter|grey matter]] volumes in bilateral lenticular nuclei, extending to the caudate nuclei, with decreased grey matter volumes in bilateral dorsal [[Biology:Medial frontal gyrus|medial frontal]]/[[Biology:Anterior cingulate cortex|anterior cingulate]] gyri.<ref name="Radua and Mataix-Cols, 2009">{{cite journal | vauthors = Radua J, Mataix-Cols D | title = Voxel-wise meta-analysis of grey matter changes in obsessive-compulsive disorder | journal = The British Journal of Psychiatry | volume = 195 | issue = 5 | pages = 393–402 | date = November 2009 | pmid = 19880927 | doi = 10.1192/bjp.bp.108.055046 | doi-access = free }}</ref><ref name="radua2010">{{cite journal | vauthors = Radua J, van den Heuvel OA, Surguladze S, Mataix-Cols D | title = Meta-analytical comparison of voxel-based morphometry studies in obsessive-compulsive disorder vs other anxiety disorders | journal = Archives of General Psychiatry | volume = 67 | issue = 7 | pages = 701–711 | date = July 2010 | pmid = 20603451 | doi = 10.1001/archgenpsychiatry.2010.70 | s2cid = 9501322 | doi-access =  }}</ref> These findings contrast with those in people with other anxiety disorders, who evince decreased (rather than increased) grey matter volumes in bilateral lenticular/caudate nuclei, as well as decreased grey matter volumes in bilateral dorsal [[Biology:Medial frontal gyrus|medial frontal]]/[[Biology:Anterior cingulate cortex|anterior cingulate]] gyri.<ref name="radua2010" /> Increased [[Biology:White matter|white matter]] volume and decreased [[Fractional anisotropy|fractional anisotropy]] in anterior midline tracts has been observed in OCD, possibly indicating increased fiber crossings.<ref>{{cite journal | vauthors = Radua J, Grau M, van den Heuvel OA, Thiebaut de Schotten M, Stein DJ, Canales-Rodríguez EJ, Catani M, Mataix-Cols D | display-authors = 6 | title = Multimodal voxel-based meta-analysis of white matter abnormalities in obsessive-compulsive disorder | journal = Neuropsychopharmacology | volume = 39 | issue = 7 | pages = 1547–1557 | date = June 2014 | pmid = 24407265 | pmc = 4023155 | doi = 10.1038/npp.2014.5 }}</ref>

=== Cognitive models ===

Generally, two categories of models for OCD have been postulated. The first category involves deficits in executive dysfunction and is based on the observed structural and functional abnormalities in the dlPFC, [[Biology:Striatum|striatum]] and thalamus. The second category involves dysfunctional modulatory control and primarily relies on observed functional and structural differences in the ACC, mPFC, and OFC.<ref>{{cite journal | vauthors = Friedlander L, Desrocher M | title = Neuroimaging studies of obsessive-compulsive disorder in adults and children | journal = Clinical Psychology Review | volume = 26 | issue = 1 | pages = 32–49 | date = January 2006 | pmid = 16242823 | doi = 10.1016/j.cpr.2005.06.010 }}</ref><ref>{{cite journal | vauthors = Stern ER, Taylor SF | title = Cognitive neuroscience of obsessive-compulsive disorder | journal = The Psychiatric Clinics of North America | volume = 37 | issue = 3 | pages = 337–352 | date = September 2014 | pmid = 25150566 | doi = 10.1016/j.psc.2014.05.004 | s2cid = 207442722 }}</ref>

One proposed model suggests that dysfunction in the [[Biology:Orbitofrontal cortex|OFC]] leads to improper valuation of behaviors and decreased behavioral control, while the observed alterations in [[Medicine:Amygdala|amygdala]] activations leads to exaggerated fears and representations of negative stimuli.<ref name="Wood">{{cite journal | vauthors = Wood J, Ahmari SE | title = A Framework for Understanding the Emerging Role of Corticolimbic-Ventral Striatal Networks in OCD-Associated Repetitive Behaviors | journal = Frontiers in Systems Neuroscience | volume = 9 | page = 171 | date = 2015 | pmid = 26733823 | pmc = 4681810 | doi = 10.3389/fnsys.2015.00171 | doi-access = free }}</ref>

Due to the [[Chemistry:Homogeneity and heterogeneity|heterogeneity]] of OCD symptoms, studies differentiating various symptoms have been performed. Symptom-specific neuroimaging abnormalities include the hyperactivity of caudate and ACC in checking rituals, while finding increased activity of cortical and [[Biology:Cerebellum|cerebellar]] regions in contamination-related symptoms. Neuroimaging differentiating content of intrusive thoughts has found differences between aggressive as opposed to [[Social:Taboo|taboo]] thoughts, finding increased connectivity of the [[Medicine:Amygdala|amygdala]], ventral striatum, and [[Biology:Ventromedial prefrontal cortex|ventromedial prefrontal cortex]] in aggressive symptoms, while observing increased connectivity between the ventral striatum and insula in sexual or religious intrusive thoughts.<ref>{{cite journal | vauthors = Nakao T, Okada K, Kanba S | title = Neurobiological model of obsessive-compulsive disorder: evidence from recent neuropsychological and neuroimaging findings | journal = Psychiatry and Clinical Neurosciences | volume = 68 | issue = 8 | pages = 587–605 | date = August 2014 | pmid = 24762196 | doi = 10.1111/pcn.12195 | s2cid = 5528241 | doi-access = free }}</ref>

Another model proposes that affective dysregulation links excessive reliance on habit-based action selection<ref>{{cite journal | vauthors = Barahona-Corrêa JB, Camacho M, Castro-Rodrigues P, Costa R, Oliveira-Maia AJ | title = From Thought to Action: How the Interplay Between Neuroscience and Phenomenology Changed Our Understanding of Obsessive-Compulsive Disorder | journal = Frontiers in Psychology | volume = 6 | page = 1798 | date = 2015 | pmid = 26635696 | pmc = 4655583 | doi = 10.3389/fpsyg.2015.01798 | doi-access = free }}</ref> with compulsions. This is supported by the observation that those with OCD demonstrate decreased activation of the ventral striatum when anticipating monetary reward, as well as increased functional connectivity between the VS and the OFC. Furthermore, those with OCD demonstrate reduced performance in [[Philosophy:Classical conditioning|Pavlovian]] fear-extinction tasks, hyperresponsiveness in the amygdala to fearful stimuli, and hyporesponsiveness in the amygdala when exposed to positively valanced stimuli. Stimulation of the [[Biology:Nucleus accumbens|nucleus accumbens]] has also been observed to effectively alleviate both obsessions and compulsions, supporting the role of affective dysregulation in generating both.<ref name="Wood" />

=== Neurobiological ===

From the observation of the efficacy of antidepressants in OCD, a serotonin hypothesis of OCD has been formulated. Studies of peripheral markers of serotonin, as well as challenges with proserotonergic compounds have yielded inconsistent results, including evidence pointing towards basal hyperactivity of [[Chemistry:Serotonin|serotonergic]] systems.<ref>{{Cite book | vauthors = Davis KL |title=Neuropsychopharmacology: the fifth generation of progress: an official publication of the American College of Neuropsychopharmacology |date=2002 |publisher=Lippincott Williams & Wilkins |isbn=978-0-7817-2837-9 |edition=5th |location=Philadelphia, Pa. |pages=1609–1610}}</ref> [[Chemistry:Serotonin receptor|Serotonin receptor]] and transporter binding studies have yielded conflicting results, including higher and lower serotonin receptor 5-HT2A and [[Biology:Serotonin transporter|serotonin transporter]] binding potentials that were normalized by treatment with SSRIs. Despite inconsistencies in the types of abnormalities found, evidence points towards dysfunction of serotonergic systems in OCD.<ref>{{Cite book | vauthors = Muller CP, Jacobs BL, Dijk A, Klompmakers A, Deny D |title=Handbook of the behavioral neurobiology of serotonin s |date=2009 |publisher=Academic |isbn=978-0-12-374634-4 |edition=1st |location=London |pages=547–558 |chapter=4.4 The Serotonergic System in Obsessive-Compulsive Disorder}}</ref> Orbitofrontal cortex overactivity is attenuated in people who have successfully responded to SSRI medication, a result believed to be caused by increased stimulation of [[Chemistry:Serotonin|serotonin]] receptors [[Biology:5-HT2A receptor|5-HT2A]] and [[Biology:5-HT receptor|5-HT2C]].<ref>{{cite journal | vauthors = Kim KW, Lee DY | title = Obsessive-compulsive disorder associated with a left orbitofrontal infarct | journal = The Journal of Neuropsychiatry and Clinical Neurosciences | volume = 14 | issue = 1 | pages = 88–89 | year = 2002 | pmid = 11884667 | doi = 10.1176/appi.neuropsych.14.1.88 }}</ref>

A complex relationship between [[Biology:Dopamine|dopamine]] and OCD has been observed. Although antipsychotics, which act by [[Chemistry:Dopamine antagonist|antagonizing dopamine receptors]], may improve some cases of OCD, they frequently exacerbate others. Antipsychotics, in the low doses used to treat OCD, may actually increase the release of dopamine in the [[Biology:Prefrontal cortex|prefrontal cortex]], through inhibiting autoreceptors. Further complicating things is the efficacy of [[Chemistry:Amphetamine|amphetamine]]s, decreased [[Biology:Dopamine transporter|dopamine transporter]] activity observed in OCD,<ref>{{cite journal | vauthors = Wood J, Ahmari SE | title = A Framework for Understanding the Emerging Role of Corticolimbic-Ventral Striatal Networks in OCD-Associated Repetitive Behaviors | journal = Frontiers in Systems Neuroscience | volume = 9 | page = 171 | date = 17 December 2015 | pmid = 26733823 | pmc = 4681810 | doi = 10.3389/fnsys.2015.00171 | doi-access = free }}</ref> and low levels of [[Biology:Dopamine receptor D2|D2]] binding in the [[Biology:Striatum|striatum]].<ref name="glutamate" /> Furthermore, increased dopamine release in the [[Biology:Nucleus accumbens|nucleus accumbens]] after deep brain stimulation correlates with improvement in symptoms, pointing to reduced dopamine release in the striatum playing a role in generating symptoms.<ref>{{Cite book | vauthors = Graat I, Figee M, Denys D |title=Obsessive-Compulsive Disorder: Phenomenology, Pathophysiology and Treatment  |publisher=Oxford University Press | veditors = Pittinger C |chapter=Neurotransmitter Dysregulation in OCD}}</ref>

Abnormalities in [[Biology:Glutamatergic|glutamatergic]] [[Biology:Neurotransmission|neurotransmission]] have been implicated in OCD. Findings such as increased [[Biology:Cerebrospinal fluid|cerebrospinal]] [[Chemistry:Glutamic acid|glutamate]], less consistent abnormalities observed in neuroimaging studies, and the efficacy of some glutamatergic drugs (such as the glutamate-inhibiting [[Chemistry:Riluzole|riluzole]]) have implicated glutamate in OCD.<ref name="glutamate">{{cite journal | vauthors = Pittenger C, Bloch MH, Williams K | title = Glutamate abnormalities in obsessive compulsive disorder: neurobiology, pathophysiology, and treatment | journal = Pharmacology & Therapeutics | volume = 132 | issue = 3 | pages = 314–332 | date = December 2011 | pmid = 21963369 | pmc = 3205262 | doi = 10.1016/j.pharmthera.2011.09.006 }}</ref> OCD has been associated with reduced [[Chemistry:N-Acetylaspartic acid|N-Acetylaspartic acid]] in the mPFC, which is thought to reflect neuron density or functionality, although the exact interpretation has not been established.<ref>{{cite journal | vauthors = Aoki Y, Aoki A, Suwa H | title = Reduction of N-acetylaspartate in the medial prefrontal cortex correlated with symptom severity in obsessive-compulsive disorder: meta-analyses of (1)H-MRS studies | journal = Translational Psychiatry | volume = 2 | issue = 8 | pages = e153 | date = August 2012 | pmid = 22892718 | pmc = 3432192 | doi = 10.1038/tp.2012.78 }}</ref>

== Diagnosis ==

Formal diagnosis may be performed by a [[Social:Psychologist|psychologist]], psychiatrist, clinical [[Social:Social work|social work]]er, or other licensed mental health professional. OCD, like other mental and behavioral health disorders, cannot be diagnosed by a medical exam,<ref name=":14" /> nor are there any medical exams that can predict if one will fall victim to such illnesses. To be diagnosed with OCD, a person must have obsessions, compulsions, or both, according to the [[Medicine:Diagnostic and Statistical Manual of Mental Disorders|Diagnostic and Statistical Manual of Mental Disorders]] (DSM). The DSM notes that there are multiple characteristics that can turn obsessions and compulsions from normalized behavior to "clinically significant". There has to be recurring and strong thoughts or impulsive that intrude on the day-to-day lives of the patients and cause noticeable levels of anxiousness.<ref name="DSM52" />

These thoughts, impulses, or images are of a degree or type that lies outside the [[Social:Normality (behavior)|normal]] range of worries about conventional problems.<ref name="Quick">''Quick Reference to the Diagnostic Criteria from DSM-IV-TR''. Arlington, VA: American Psychiatric Association, 2000.</ref> A person may attempt to ignore or [[Philosophy:Thought suppression|suppress]] such obsessions, neutralize them with another thought or action, or try to rationalize their anxiety away. People with OCD tend to recognize their obsessions as irrational.

Compulsions become clinically significant when a person feels driven to perform them in response to an obsession, or according to rules that must be applied rigidly, and when the person consequently feels or causes significant distress. Therefore, while many people who do not have OCD may perform actions often associated with OCD (such as ordering items in a pantry by height), the distinction with clinically significant OCD lies in the fact that the person with OCD must perform these actions to avoid significant psychological distress. These behaviors or mental acts are aimed at preventing or reducing distress or preventing some dreaded event or situation; however, these activities are not logically or practically connected to the issue, or, they are excessive.

Moreover, the obsessions or compulsions must be time-consuming, often taking up more than one hour per day, or cause impairment in social, occupational, or scholastic functioning.<ref name="Quick" /> It is helpful to quantify the severity of symptoms and impairment before and during treatment for OCD. In addition to the person's estimate of the time spent each day harboring obsessive-compulsive thoughts or behaviors, concrete tools can be used to gauge the person's condition. This may be done with rating scales, such as the Yale–Brown Obsessive Compulsive Scale (Y-BOCS; expert rating)<ref>{{cite journal | vauthors = Goodman WK, Price LH, Rasmussen SA, Mazure C, Fleischmann RL, Hill CL, Heninger GR, Charney DS | display-authors = 6 | title = The Yale-Brown Obsessive Compulsive Scale. I. Development, use, and reliability | journal = Archives of General Psychiatry | volume = 46 | issue = 11 | pages = 1006–1011 | date = November 1989 | pmid = 2684084 | doi = 10.1001/archpsyc.1989.01810110048007 }}</ref> or the obsessive-compulsive inventory (OCI-R; self-rating).<ref>{{cite journal | vauthors = Foa EB, Huppert JD, Leiberg S, Langner R, Kichic R, Hajcak G, Salkovskis PM | title = The Obsessive-Compulsive Inventory: development and validation of a short version | journal = Psychological Assessment | volume = 14 | issue = 4 | pages = 485–496 | date = December 2002 | pmid = 12501574 | doi = 10.1037/1040-3590.14.4.485 | s2cid = 18815147 }}</ref> With measurements such as these, psychiatric consultation can be more appropriately determined, as it has been standardized.<ref name="Fenske_2009" />

In regards to diagnosing, the health professional also looks to make sure that the signs of obsessions and compulsions are not the results of any drugs, prescription or recreational, that the patient may be taking.<ref name=":15">{{Cite web |title=Obsessive Compulsive Disorder (OCD): Symptoms & Treatment |url=https://my.clevelandclinic.org/health/diseases/9490-obsessive-compulsive-disorder |access-date=2022-10-12 |website=Cleveland Clinic}}</ref>

There are several types of obsessive thoughts that are found commonly in those with OCD. Some of these include fear of germs, hurting loved ones, embarrassment, neatness, societally unacceptable sexual thoughts etc.<ref name=":15" /> Within OCD, these specific categories are often diagnosed into their own type of OCD.<ref name="DSM52" />

OCD is sometimes placed in a group of disorders called the obsessive–compulsive spectrum.<ref>{{cite journal | vauthors = Starcevic V, Janca A | title = Obsessive-compulsive spectrum disorders: still in search of the concept-affirming boundaries | journal = Current Opinion in Psychiatry | volume = 24 | issue = 1 | pages = 55–60 | date = January 2011 | pmid = 20827198 | doi = 10.1097/yco.0b013e32833f3b58 | s2cid = 41312244 }}</ref>

Another criterion in the DSM is that a person's mental illness does not fit one of the other categories of a mental disorder better. That is to say, if the obsessions and compulsions of a patient could be better described by [[Medicine:Trichotillomania|trichotillomania]], it would not be diagnosed as OCD.<ref name="DSM52" /> That being said, OCD does often go hand in hand with other mental disorders. For this reason, one may be diagnosed with multiple mental disorders at once.<ref>{{cite journal | vauthors = Freckelton I | title = Obsessive compulsive disorder and obsessive compulsive personality disorder and the criminal law | journal = Psychiatry, Psychology, and Law | volume = 27 | issue = 5 | pages = 831–852 | date = June 2020 | pmid = 33833612 | pmc = 8009125 | doi = 10.1080/13218719.2020.1745497 }}</ref>

A different aspect of the diagnoses is the degree of insight had by the individual in regards to the truth of the obsessions. There are three levels, good/fair, poor and absent/delusional. Good/fair indicated that the patient is aware that the obsessions they have are not true or probably not true.<ref name="DSM52" /> Poor indicates that the patient believes their obsessional beliefs are probably true.<ref name="DSM52" /> Absent/delusional indicates that they fully believe their obsessional thoughts to be true.<ref name="DSM52" /> Approximately 4% or fewer individuals with OCD will be diagnosed as absent/delusional.<ref name="DSM52" /> Additionally, as many as 30% of those with OCD also have a lifetime tic disorder, meaning they have been diagnosed with a tic disorder at some point in their life.<ref name="DSM52" />

There are several different types of tics that have been observed in individuals with OCD. These include but are not limited to, "grunting", "jerking" or "shrugging" body parts, sniffling, and excessive blinking.<ref name=":15" />

There has been a significant amount of progress over the last few decades, and as of 2022 there is statically significant improvement in the diagnostic process for individuals with OCD. One study found that of two groups of individuals, one with participants under the age of 27.25 and one with participants over that age, those in the younger group experienced a significantly faster time between the onset of OCD tendencies and their formal diagnoses.<ref>{{Cite journal | vauthors = Hezel D |date=January 2022 |title=Delay to diagnosis in OCD |journal=Journal of Obsessive-Compulsive and Related Disorders |volume=32 |page=100709 |doi=10.1016/j.jocrd.2022.100709 |s2cid=245996392 }}</ref>

=== Differential diagnosis ===
OCD is often confused with the separate condition [[Medicine:Obsessive–compulsive personality disorder|obsessive–compulsive personality disorder]] (OCPD). OCD is [[Philosophy:Egosyntonic and egodystonic|egodystonic]], meaning that the disorder is incompatible with the individual's [[Philosophy:Self-concept|self-concept]].<ref name="Aardema, F. 2007" /><ref name="Aardema">{{Cite journal | vauthors = Aardema F, O'Connor K |year=2003 |title=Seeing white bears that are not there: Inference processes in obsessions |journal=Journal of Cognitive Psychotherapy |volume=17 |pages=23–37 |doi= 10.1891/jcop.17.1.23.58270 |s2cid=143040967}}</ref> As egodystonic disorders go against a person's self-concept, they tend to cause much distress. OCPD, on the other hand, is ''[[Philosophy:Egosyntonic and egodystonic|egosyntonic]]'', marked by the person's acceptance that the characteristics and behaviors displayed as a result are compatible with their [[Philosophy:Self-image|self-image]], or are otherwise appropriate, correct, or reasonable.

As a result, people with OCD are often aware that their behavior is not rational, and are unhappy about their obsessions, but nevertheless feel compelled by them.<ref name="carter">Carter, K. "Obsessive–compulsive personality disorder." PSYC 210 lecture: Oxford College of Emory University. Oxford, GA. 11 April 2006.</ref> By contrast, people with OCPD are not aware of anything abnormal; they will readily explain why their actions are rational. It is usually impossible to convince them otherwise, and they tend to derive pleasure from their obsessions or compulsions.<ref name="carter" />

== Management ==
[[Medicine:Cognitive behavioral therapy|Cognitive behavioral therapy]] (CBT) and psychotropic medications are the first-line treatments for OCD.<ref name="NIH20152" /><ref name="NICE2005" />

=== Therapy ===

[[File:Pennsylvania Capitol front door keyhole.jpg|thumb|One exposure and ritual prevention activity would be to check the lock only once and then leave.]]

One specific CBT technique used is called exposure and response prevention (ERP), which involves teaching the person to deliberately come into contact with situations that trigger obsessive thoughts and fears (exposure), without carrying out the usual compulsive acts associated with the obsession (response prevention). This technique causes patients to gradually learn to tolerate the discomfort and anxiety associated with not performing their compulsions. For many patients, ERP is the add-on treatment of choice when [[Chemistry:Selective serotonin reuptake inhibitor|selective serotonin reuptake inhibitor]]s (SSRIs) or [[Chemistry:Serotonin–norepinephrine reuptake inhibitor|serotonin-norepinephrine reuptake inhibitors]] (SNRIs) medication does not effectively treat OCD symptoms, or vice versa, for individuals who begin treatment with psychotherapy.<ref name=":10" /> Modalities differ in ERP treatment but both virtual reality based as well as unguided computer assisted treatment programs have shown effective results in treatment programs.<ref>{{cite journal | vauthors = Imai H, Tajika A, Narita H, Yoshinaga N, Kimura K, Nakamura H, Takeshima N, Hayasaka Y, Ogawa Y, Furukawa T | display-authors = 6 | title = Unguided Computer-Assisted Self-Help Interventions Without Human Contact in Patients With Obsessive-Compulsive Disorder: Systematic Review and Meta-analysis | journal = Journal of Medical Internet Research | volume = 24 | issue = 4 | pages = e35940 | date = April 2022 | pmid = 35451993 | pmc = 9073609 | doi = 10.2196/35940 | doi-access = free }}</ref><ref>{{cite journal | vauthors = van Loenen I, Scholten W, Muntingh A, Smit J, Batelaan N | title = The Effectiveness of Virtual Reality Exposure-Based Cognitive Behavioral Therapy for Severe Anxiety Disorders, Obsessive-Compulsive Disorder, and Posttraumatic Stress Disorder: Meta-analysis | journal = Journal of Medical Internet Research | volume = 24 | issue = 2 | pages = e26736 | date = February 2022 | pmid = 35142632 | pmc = 8874794 | doi = 10.2196/26736 | doi-access = free }}</ref>

For example, a patient might be asked to touch something very mildly contaminated (exposure), and wash their hands only once afterward (response prevention). Another example might entail asking the patient to leave the house and check the lock only once (exposure), without going back to check again (response prevention). After succeeding at one stage of treatment, the patient's level of discomfort in the exposure phase can be increased. When this therapy is successful, the patient will quickly [[Philosophy:Habituation|habituate]] to an anxiety-producing situation, discovering a considerable drop in anxiety level.<ref name="baojournal.com">Huppert & Roth: (2003) Treating Obsessive-Compulsive Disorder with Exposure and Response Prevention. ''The Behavior Analyst Today, 4 (1),'' 66 – 70 [http://www.baojournal.com/ BAO] {{webarchive|url=https://web.archive.org/web/20100323025324/http://baojournal.com/ |date=23 March 2010 }}</ref>

ERP has a strong evidence base, and is considered the most effective treatment for OCD.<ref name="baojournal.com" /> However, this claim was doubted by some researchers in 2000, who criticized the quality of many studies.<ref name="pmid10910778">{{cite journal | vauthors = Klein DF | title = Flawed meta-analyses comparing psychotherapy with pharmacotherapy | journal = The American Journal of Psychiatry | volume = 157 | issue = 8 | pages = 1204–1211 | date = August 2000 | pmid = 10910778 | doi = 10.1176/appi.ajp.157.8.1204 }}</ref> While ERP can lead a majority of clients to improvements, many do not reach remission or become asymptomatic;<ref>{{Cite journal |last1=Fisher |first1=P. L. |last2=Cherry |first2=M. G. |last3=Stuart |first3=T. |last4=Rigby |first4=J. W. |last5=Temple |first5=J. |date=2020-10-01 |title=People with obsessive-compulsive disorder often remain symptomatic following psychological treatment: A clinical significance analysis of manualised psychological interventions |url=https://www.sciencedirect.com/science/article/pii/S0165032720323776 |journal=Journal of Affective Disorders |volume=275 |pages=94–108 |doi=10.1016/j.jad.2020.06.019 |pmid=32658831 |s2cid=220521468 |issn=0165-0327}}</ref> some therapists are also hesitant to use this approach.<ref>{{Cite journal |last1=Schneider |first1=Sophie C. |last2=Knott |first2=Lindsey |last3=Cepeda |first3=Sandra L. |last4=Hana |first4=Lynn M. |last5=McIngvale |first5=Elizabeth |last6=Goodman |first6=Wayne K. |last7=Storch |first7=Eric A. |date=May 2020 |title=Serious negative consequences associated with exposure and response prevention for obsessive‐compulsive disorder: A survey of therapist attitudes and experiences |url=https://onlinelibrary.wiley.com/doi/10.1002/da.23000 |journal=Depression and Anxiety |language=en |volume=37 |issue=5 |pages=418–428 |doi=10.1002/da.23000 |pmid=32048376 |s2cid=211085261 |issn=1091-4269|doi-access=free }}</ref>

[[Philosophy:Acceptance and commitment therapy|Acceptance and commitment therapy]] (ACT), a newer therapy also used to treat anxiety and depression, has also been found to be effective in treatment of OCD.<ref>{{cite journal | vauthors = Twohig MP, Hayes SC, Masuda A | title = Increasing willingness to experience obsessions: acceptance and commitment therapy as a treatment for obsessive-compulsive disorder | journal = Behavior Therapy | volume = 37 | issue = 1 | pages = 3–13 | date = March 2006 | pmid = 16942956 | doi = 10.1016/j.beth.2005.02.001 | url = https://scholarworks.gsu.edu/psych_facpub/100 }}</ref><ref>{{Cite journal | vauthors = Twohig MP, Abramowitz JS, Bluett EJ, Fabricant LE, Jacoby RJ, Morrison KL, Reuman L, Smith BM  |date=2015-07-01 |title=Exposure therapy for OCD from an acceptance and commitment therapy (ACT) framework |url=https://www.sciencedirect.com/science/article/pii/S2211364914001043 |journal=Journal of Obsessive-Compulsive and Related Disorders |language=en |volume=6 |pages=167–173 |doi=10.1016/j.jocrd.2014.12.007 |issn=2211-3649}}</ref> ACT uses acceptance and [[Philosophy:Mindfulness|mindfulness]] strategies to teach patients not to overreact to or avoid unpleasant thoughts and feelings but rather "move toward valued behavior."<ref>{{Cite web | vauthors = Hayes SC |title=ACT {{!}} Association for Contextual Behavioral Science |url=https://contextualscience.org/act |access-date=2022-07-07 |website=contextualscience.org}}</ref><ref>{{Cite book | vauthors = Hayes SC, Strosahl K, Wilson KG |title=Acceptance and commitment therapy: the process and practice of mindful change |date=2012 |publisher=Guilford Press |isbn=978-1-60918-962-4 |edition=2nd |location=New York |oclc=713181786}}</ref>

[[Medicine:Inference-based therapy|Inference-based therapy]] (IBT) is a form of [[Medicine:Cognitive therapy|cognitive therapy]] specifically developed for treating OCD.<ref name="O'Connor, K. 2005">O'Connor, K., Aardema, F., & Pelissier, M.-C. (2005). Beyond reasonable doubt: Reasoning processes in obsessive-compulsive disorder and related disorders. Chichester: John Wiley & Sons.</ref> The therapy posits that individuals with OCD put a greater emphasis on an imagined possibility than on what can be perceived with the [[Philosophy:Sense|sense]]s, and confuse the imagined possibility with reality, in a process called [[Inferential confusion|inferential confusion]].<ref>Aardema, F., O'Connor, K. P., Emmelkamp, P. M., Marchand, A., & Todorov, C. (2005). Inferential confusion in obsessive-compulsive disorder: the inferential confusion questionnaire. Behaviour Research & Therapy, 43, 293-308.</ref> According to inference-based therapy, obsessional thinking occurs when the person replaces reality and real probabilities with imagined possibilities.<ref>O'Connor, K. (2002). Intrusions and inferences in obsessive compulsive disorder. Clinical Psychology & Psychotherapy, 9, 38-46.</ref> The goal of inference-based therapy is to reorient clients towards trusting the senses and relating to reality in a normal, non-effortful way. Differences between normal and obsessional doubts are presented, and clients are encouraged to use their senses and reasoning as they do in non-obsessive-compulsive disorder situations.<ref>O'Connor, K., & Aardema, F. (2012). Clinician's handbook for obsessive compulsive disorder: Inference-based therapy. Chichester: Wiley-Blackwell.</ref><ref name="O'Connor, K. 2005"/> Research on Inference-Based Cognitive-Behavior Therapy (I-CBT) suggests it can lead to improvements for those with OCD.<ref>{{Cite journal |last1=Aardema |first1=Frederick |last2=Bouchard |first2=Stéphane |last3=Koszycki |first3=Diana |last4=Lavoie |first4=Marc E. |last5=Audet |first5=Jean-Sebastien |last6=O'Connor |first6=Kieron |date=2022 |title=Evaluation of Inference-Based Cognitive-Behavioral Therapy for Obsessive-Compulsive Disorder: A Multicenter Randomized Controlled Trial with Three Treatment Modalities |journal=Psychotherapy and Psychosomatics |volume=91 |issue=5 |pages=348–359 |doi=10.1159/000524425 |issn=1423-0348 |pmid=35584639|s2cid=248890026 |doi-access=free }}</ref>

A 2007 [[Organization:Cochrane (organisation)|Cochrane review]] found that psychological interventions derived from CBT models, such as ERP, ACT, and IBT, were more effective than non-CBT interventions.<ref name=":17">{{cite journal | vauthors = Gava I, Barbui C, Aguglia E, Carlino D, Churchill R, De Vanna M, McGuire HF | title = Psychological treatments versus treatment as usual for obsessive compulsive disorder (OCD) | journal = The Cochrane Database of Systematic Reviews | issue = 2 | pages = CD005333 | date = April 2007 | pmid = 17443583 | doi = 10.1002/14651858.CD005333.pub2 }}</ref> Other forms of psychotherapy, such as psychodynamics and [[Social:Psychoanalysis|psychoanalysis]], may help in managing some aspects of the disorder. However, in 2007, the American Psychiatric Association (APA) noted a lack of [[Scientific control|controlled studies]] showing their efficacy, "in dealing with the core symptoms of OCD."<ref name="APAguidelines">{{cite journal | vauthors = Koran LM, Hanna GL, Hollander E, Nestadt G, Simpson HB | title = Practice guideline for the treatment of patients with obsessive-compulsive disorder | journal = The American Journal of Psychiatry | volume = 164 | issue = 7 Suppl | pages = 5–53 | date = July 2007 | pmid = 17849776 }}</ref> For body-focused repetitive behaviors (BFRB), behavioral interventions such as habit-reversal training and [[Medicine:Decoupling for body-focused repetitive behaviors|decoupling]] are recommended.<ref name=":1" /><ref name=":2" />

Psychotherapy in combination with psychiatric medication may be more effective than either option alone for individuals with severe OCD.<ref>{{cite journal | vauthors = Skapinakis P, Caldwell DM, Hollingworth W, Bryden P, Fineberg NA, Salkovskis P, Welton NJ, Baxter H, Kessler D, Churchill R, Lewis G | display-authors = 6 | title = Pharmacological and psychotherapeutic interventions for management of obsessive-compulsive disorder in adults: a systematic review and network meta-analysis | journal = The Lancet. Psychiatry | volume = 3 | issue = 8 | pages = 730–739 | date = August 2016 | pmid = 27318812 | pmc = 4967667 | doi = 10.1016/S2215-0366(16)30069-4 }}</ref><ref>{{cite journal | vauthors = Wheaton MG, DeSantis SM, Simpson HB | title = Network meta-analyses and treatment recommendations for obsessive-compulsive disorder | journal = The Lancet. Psychiatry | volume = 3 | issue = 10 | page = 920 | date = October 2016 | pmid = 27692263 | pmc = 6690590 | doi = 10.1016/S2215-0366(16)30280-2 }}</ref><ref>{{cite journal | vauthors = Hirschtritt ME, Bloch MH, Mathews CA | title = Obsessive-Compulsive Disorder: Advances in Diagnosis and Treatment | journal = JAMA | volume = 317 | issue = 13 | pages = 1358–1367 | date = April 2017 | pmid = 28384832 | doi = 10.1001/jama.2017.2200 | s2cid = 13660201 }}</ref> ERP coupled with weight restoration and serotonin reuptake inhibitors has proven the most effective when treating OCD and an eating disorder simultaneously.<ref>{{cite journal | vauthors = Simpson HB, Wetterneck CT, Cahill SP, Steinglass JE, Franklin ME, Leonard RC, Weltzin TE, Riemann BC | display-authors = 6 | title = Treatment of obsessive-compulsive disorder complicated by comorbid eating disorders | journal = Cognitive Behaviour Therapy | volume = 42 | issue = 1 | pages = 64–76 | date = 2013-03-01 | pmid = 23316878 | pmc = 3947513 | doi = 10.1080/16506073.2012.751124 }}</ref>

=== Medication ===
[[File:JZoloft JPN.jpg|thumb|A blister pack of sertraline under the brand name Zoloft]]
The medications most frequently used to treat OCD are antidepressants, including [[Chemistry:Selective serotonin reuptake inhibitor|selective serotonin reuptake inhibitor]]s (SSRIs) and [[Chemistry:Serotonin–norepinephrine reuptake inhibitor|serotonin-norepinephrine reuptake inhibitors]] (SNRIs).<ref name="NEJM2014" /> [[Chemistry:Sertraline|Sertraline]] and [[Chemistry:Fluoxetine|fluoxetine]] are effective in treating OCD for children and adolescents.<ref name=":02">{{Cite journal |date=2022-11-03 |title=Antidepressants for children and teenagers: what works for anxiety and depression? |url=https://evidence.nihr.ac.uk/collection/antidepressants-for-children-and-teenagers-what-works-anxiety-depression/ |journal=NIHR Evidence |type=Plain English summary |language=en |publisher=National Institute for Health and Care Research |doi=10.3310/nihrevidence_53342|s2cid=253347210 }}</ref><ref name=":42">{{cite journal |vauthors=Boaden K, Tomlinson A, Cortese S, Cipriani A |date=2020-09-02 |title=Antidepressants in Children and Adolescents: Meta-Review of Efficacy, Tolerability and Suicidality in Acute Treatment |journal=Frontiers in Psychiatry |volume=11 |page=717 |doi=10.3389/fpsyt.2020.00717 |pmc=7493620 |pmid=32982805|doi-access=free }}</ref><ref name=":52">{{cite journal |display-authors=6 |vauthors=Correll CU, Cortese S, Croatto G, Monaco F, Krinitski D, Arrondo G, Ostinelli EG, Zangani C, Fornaro M, Estradé A, Fusar-Poli P, Carvalho AF, Solmi M |date=June 2021 |title=Efficacy and acceptability of pharmacological, psychosocial, and brain stimulation interventions in children and adolescents with mental disorders: an umbrella review |journal=World Psychiatry |volume=20 |issue=2 |pages=244–275 |doi=10.1002/wps.20881 |pmc=8129843 |pmid=34002501}}</ref>

SSRIs help people with OCD by inhibiting the reabsorption of serotonin by the nerve cells after they carry messages from neurons to [[Biology:Synapse|synapse]]; thus, more serotonin is available to pass further messages between nearby nerve cells.<ref name="How SSRIs work {{!}} OCD-UK" />

SSRIs are a second-line treatment of adult OCD with mild functional impairment, and as first-line treatment for those with moderate or severe impairment. In children, SSRIs can be considered as a second-line therapy in those with moderate to severe impairment, with close monitoring for psychiatric adverse effects.<ref name="NICE2005">{{Cite web |last=National Institute for Health and Clinical Excellence (NICE) |date=November 2005 |title=Obsessive-compulsive disorder: Core interventions in the treatment of obsessive-compulsive disorder and body dysmorphic disorder |url=https://www.nice.org.uk/guidance/cg31/resources/treating-obsessivecompulsive-disorder-ocd-and-body-dysmorphic-disorder-bdd-in-adults-children-and-young-people-194882077 |url-status=live |archive-url=https://web.archive.org/web/20170112001813/https://www.nice.org.uk/guidance/cg31/resources/treating-obsessivecompulsive-disorder-ocd-and-body-dysmorphic-disorder-bdd-in-adults-children-and-young-people-194882077 |archive-date=12 January 2017 |access-date=24 July 2016 |series=Information about NICE Clinical Guideline 31 |publisher=UK National Health Service (NHS)}}</ref> Patients treated with SSRIs are about twice as likely to respond to treatment as are those treated with [[Medicine:Placebo|placebo]], so this treatment is qualified as efficacious.<ref>{{cite journal | vauthors = Arroll B, Elley CR, Fishman T, Goodyear-Smith FA, Kenealy T, Blashki G, Kerse N, Macgillivray S | display-authors = 6 | title = Antidepressants versus placebo for depression in primary care | journal = The Cochrane Database of Systematic Reviews | volume = 2009 | issue = 3 | pages = CD007954 | date = July 2009 | pmid = 19588448 | doi = 10.1002/14651858.CD007954 | pmc = 10576545 | veditors = Arroll B }}</ref><ref>{{Cite web |title=Review Finds SSRIs Modestly Effective in Short-Term Treatment of OCD |url=http://www.medscape.com/viewarticle/570825+ |archive-url=https://web.archive.org/web/20130413110435/http://www.medscape.com/viewarticle/570825 |archive-date=13 April 2013}}</ref> Efficacy has been demonstrated both in short-term (6–24 weeks) treatment trials, and in discontinuation trials with durations of 28–52 weeks.<ref>{{cite journal | vauthors = Fineberg NA, Brown A, Reghunandanan S, Pampaloni I | title = Evidence-based pharmacotherapy of obsessive-compulsive disorder | journal = The International Journal of Neuropsychopharmacology | volume = 15 | issue = 8 | pages = 1173–1191 | date = September 2012 | pmid = 22226028 | doi = 10.1017/S1461145711001829 | doi-access = free | hdl = 2299/216 | hdl-access = free }}</ref><ref>{{Cite web |title=Sertraline prescribing information |url=http://www.accessdata.fda.gov/drugsatfda_docs/label/2009/019839s070,020990s032lbl.pdf |url-status=live |archive-url=https://web.archive.org/web/20150616011817/http://www.accessdata.fda.gov/drugsatfda_docs/label/2009/019839s070%2C020990s032lbl.pdf |archive-date=16 June 2015 |access-date=30 January 2015}}</ref><ref>{{Cite web |title=Paroxetine prescribing information |url=https://www.apotex.com/us/en/products/downloads/pil/paxil_irtb_ins.pdf |archive-url=https://web.archive.org/web/20150219055046/https://www.apotex.com/us/en/products/downloads/pil/paxil_irtb_ins.pdf |archive-date=19 February 2015 |access-date=30 January 2015}}</ref>

[[Chemistry:Clomipramine|Clomipramine]], a medication belonging to the class of [[Chemistry:Tricyclic antidepressant|tricyclic antidepressant]]s, appears to work as well as SSRIs, but has a higher rate of side effects.<ref name="NEJM2014" />

In 2006, the [[Organization:National Institute for Health and Care Excellence|National Institute for Health and Care Excellence]] (NICE) guidelines recommended augmentative second-generation (atypical) [[Chemistry:Antipsychotic|antipsychotic]]s for treatment-resistant OCD.<ref name="Ve2014" /> Atypical antipsychotics are not useful when used alone, and no evidence supports the use of first-generation antipsychotics.<ref name="Dec2010" /><ref>{{cite journal | vauthors = Pignon B, Tezenas du Montcel C, Carton L, Pelissolo A | title = The Place of Antipsychotics in the Therapy of Anxiety Disorders and Obsessive-Compulsive Disorders | journal = Current Psychiatry Reports | volume = 19 | issue = 12 | page = 103 | date = November 2017 | pmid = 29110139 | doi = 10.1007/s11920-017-0847-x | s2cid = 41312623 }}</ref> For OCD treatment specifically, there is tentative evidence for [[Chemistry:Risperidone|risperidone]], and insufficient evidence for [[Chemistry:Olanzapine|olanzapine]]. [[Chemistry:Quetiapine|Quetiapine]] is no better than placebo with regard to primary outcomes, but small effects were found in terms of Y-BOCS score. The efficacy of quetiapine and olanzapine are limited by an insufficient number of studies.<ref>{{cite journal | vauthors = Komossa K, Depping AM, Meyer M, Kissling W, Leucht S | title = Second-generation antipsychotics for obsessive compulsive disorder | journal = The Cochrane Database of Systematic Reviews | issue = 12 | pages = CD008141 | date = December 2010 | pmid = 21154394 | doi = 10.1002/14651858.CD008141.pub2 | s2cid = 205193449 }}</ref> A 2014 review article found two studies that indicated that [[Chemistry:Aripiprazole|aripiprazole]] was "effective in the short-term", and found that "[t]here was a small effect-size for risperidone or anti-psychotics in general in the short-term"; however, the study authors found "no evidence for the effectiveness of quetiapine or olanzapine in comparison to placebo."<ref name="Ve2014" /> While quetiapine may be useful when used in addition to an SSRI/[[Chemistry:Serotonin–norepinephrine reuptake inhibitor|SNRI]] in treatment-resistant OCD, these drugs are often poorly tolerated, and have metabolic side effects that limit their use. A guideline by the [[Organization:American Psychological Association|American Psychological Association]] suggested that [[Chemistry:Dextroamphetamine|dextroamphetamine]] may be considered by itself after more well-supported treatments have been attempted.<ref name="APA">{{cite journal | vauthors = Koran LM, Hanna GL, Hollander E, Nestadt G, Simpson HB | title = Practice guideline for the treatment of patients with obsessive-compulsive disorder | journal = The American Journal of Psychiatry | volume = 164 | issue = 7 Suppl | pages = 5–53 | date = July 2007 | pmid = 17849776 | url = http://psychiatryonline.org/pb/assets/raw/sitewide/practice_guidelines/guidelines/ocd.pdf | publisher = American Psychiatric Association }}</ref>

=== Procedures ===
[[Biology:Electroconvulsive therapy|Electroconvulsive therapy]] (ECT) has been found to have effectiveness in some severe and refractory cases.<ref>{{cite journal | vauthors = Cybulska EM | title = Obsessive-compulsive disorder, the brain and electroconvulsive therapy | journal = British Journal of Hospital Medicine | volume = 67 | issue = 2 | pages = 77–81 | date = February 2006 | pmid = 16498907 | doi = 10.12968/hmed.2006.67.2.20466 }}</ref> [[Physics:Transcranial magnetic stimulation|Transcranial magnetic stimulation]] has shown to provide therapeutic benefits in alleviating symptoms.<ref>{{cite journal | vauthors = Perera MP, Mallawaarachchi S, Miljevic A, Bailey NW, Herring SE, Fitzgerald PB | title = Repetitive Transcranial Magnetic Stimulation for Obsessive-Compulsive Disorder: A Meta-analysis of Randomized, Sham-Controlled Trials | journal = Biological Psychiatry. Cognitive Neuroscience and Neuroimaging | volume = 6 | issue = 10 | pages = 947–960 | date = October 2021 | pmid = 33775927 | doi = 10.1016/j.bpsc.2021.03.010 | s2cid = 232408932 }}</ref>

[[Unsolved:Psychosurgery|Surgery]] may be used as a last resort in people who do not improve with other treatments. In this procedure, a surgical [[Medicine:Lesion|lesion]] is made in an area of the brain (the [[Biology:Cingulate cortex|cingulate cortex]]). In one study, 30% of participants benefitted significantly from this procedure.<ref name="Barlow">Barlow, D. H. and V. M. Durand. ''Essentials of Abnormal Psychology''. California: Thomson Wadsworth, 2006.</ref> [[Biology:Deep brain stimulation|Deep brain stimulation]] and [[Biology:Vagus nerve stimulation|vagus nerve stimulation]] are possible surgical options that do not require destruction of brain tissue. In the United States, the [[Organization:Food and Drug Administration|Food and Drug Administration]] approved deep-brain stimulation for the treatment of OCD under a humanitarian device exemption, requiring that the procedure be performed only in a hospital with special qualifications to do so.<ref>{{Cite journal | vauthors = Barlas S |date=8 April 2009 |title=FDA Approves Pioneering Treatment for Obsessive- Compulsive Disorder |url=http://www.psychiatrictimes.com/ocd/article/10168/1399208 |url-status=live |journal=Psychiatric Times |volume=26 |issue=4 |archive-url=https://web.archive.org/web/20090710101738/http://www.psychiatrictimes.com/ocd/article/10168/1399208 |archive-date=10 July 2009}}</ref>

In the United States, [[Unsolved:Psychosurgery|psychosurgery]] for OCD is a treatment of last resort, and will not be performed until the person has failed several attempts at medication (at the full dosage) with augmentation, and many months of intensive cognitive–behavioral therapy with exposure and ritual/response prevention.<ref>[http://www.brainphysics.com/surgery.php Surgical Procedures for Obsessive–Compulsive Disorder] {{webarchive|url=https://web.archive.org/web/20080725094926/http://brainphysics.com/surgery.php |date=25 July 2008 }}, by M. Jahn and M. Williams, PhD,. BrainPhysics OCD Resource, Accessed 6 July 2008.</ref> Likewise, in the United Kingdom, psychosurgery cannot be performed unless a course of treatment from a suitably qualified cognitive–behavioral therapist has been carried out.

=== Children ===
Therapeutic treatment may be effective in reducing ritual behaviors of OCD for children and adolescents.<ref>{{Cite journal | vauthors = O'Donohue W, Ferguson KE |year=2006 |title=Evidence-Based Practice in Psychology and Behavior Analysis |journal=The Behavior Analyst Today |volume=7 |issue=3 |pages=335–347 |doi=10.1037/h0100155}}</ref> Similar to the treatment of adults with OCD, cognitive behavioral therapy stands as an effective and validated first line of treatment of OCD in children.<ref name="Freeman2014">{{cite journal | vauthors = Freeman J, Garcia A, Frank H, Benito K, Conelea C, Walther M, Edmunds J | title = Evidence base update for psychosocial treatments for pediatric obsessive-compulsive disorder | journal = Journal of Clinical Child and Adolescent Psychology | volume = 43 | issue = 1 | pages = 7–26 | date = 2014 | pmid = 23746138 | pmc = 3815743 | doi = 10.1080/15374416.2013.804386 }}</ref> Family involvement, in the form of behavioral observations and reports, is a key component to the success of such treatments.<ref name="Rapoport, J. E. 1989">{{cite book | vauthors = Rapoport JE | date = 1989 | title = Obsessive-compulsive Disorder in Children & Adolescents. | location = Washington | publisher = American Psychiatric Press }}</ref> Parental interventions also provide positive reinforcement for a child who exhibits appropriate behaviors as alternatives to compulsive responses. In a recent meta-analysis of evidenced-based treatment of OCD in children, family-focused individual CBT was labeled as "probably efficacious," establishing it as one of the leading psychosocial treatments for youth with OCD.<ref name="Freeman2014" /> After one or two years of therapy, in which a child learns the nature of their obsession and acquires strategies for coping, they may acquire a larger circle of friends, exhibit less shyness, and become less self-critical.<ref>{{cite book | vauthors = Adams PL | date = 1973 | title = Obsessive Children: A Sociopsychiatric Study. | location = Philadelphia | publisher = Brunner / Mazel }}</ref> Trials have shown that children and adolescents with OCD should begin treatment with the combination of CBT with a selective serotonin reuptake inhibitor or CBT alone, rather than only an SSRI.<ref name="Cognitive-Behavior Therapy, Sertral"/><ref name="Practice Parameter for the Assessme"/>

Although the known causes of OCD in younger age groups range from brain abnormalities to psychological preoccupations, life stress such as bullying and traumatic familial deaths may also contribute to childhood cases of OCD, and acknowledging these stressors can play a role in treating the disorder.<ref name="pmid19378573">{{cite journal | vauthors = D'Alessandro TM | title = Factors influencing the onset of childhood obsessive compulsive disorder | journal = Pediatric Nursing | volume = 35 | issue = 1 | pages = 43–46 | year = 2009 | pmid = 19378573 }}</ref>

== Prognosis ==
[[Philosophy:Quality of life|Quality of life]] is reduced across all domains in OCD. While psychological or pharmacological treatment can lead to a reduction of OCD symptoms and an increase in reported quality of life, symptoms may persist at moderate levels even following adequate treatment courses, and completely symptom-free periods are uncommon.<ref name="pmid15533282">{{cite journal | vauthors = Eddy KT, Dutra L, Bradley R, Westen D | title = A multidimensional meta-analysis of psychotherapy and pharmacotherapy for obsessive-compulsive disorder | journal = Clinical Psychology Review | volume = 24 | issue = 8 | pages = 1011–1030 | date = December 2004 | pmid = 15533282 | doi = 10.1016/j.cpr.2004.08.004 | s2cid = 6582600 }}</ref><ref>{{cite journal | vauthors = Subramaniam M, Soh P, Vaingankar JA, Picco L, Chong SA | title = Quality of life in obsessive-compulsive disorder: impact of the disorder and of treatment | journal = CNS Drugs | volume = 27 | issue = 5 | pages = 367–383 | date = May 2013 | pmid = 23580175 | doi = 10.1007/s40263-013-0056-z | s2cid = 8038340 }}</ref> In pediatric OCD, around 40% still have the disorder in adulthood, and around 40% qualify for [[Medicine:Remission|remission]].<ref>{{cite journal | vauthors = Boileau B | title = A review of obsessive-compulsive disorder in children and adolescents | journal = Dialogues in Clinical Neuroscience | volume = 13 | issue = 4 | pages = 401–411 | date = 2011 | pmid = 22275846 | pmc = 3263388 | doi = 10.31887/DCNS.2011.13.4/bboileau }}</ref> The risk of having at least one comorbid personality disorder in OCD is 52%, which is the highest among anxiety disorders and greatly impacts its management and prognosis.<ref>{{cite journal |last1=Thamby |first1=Abel |last2=Khanna |first2=Sumant |title=The role of personality disorders in obsessive-compulsive disorder |journal=Indian Journal of Psychiatry |date=2019 |volume=61 |issue=7 |pages=S114–S118 |doi=10.4103/psychiatry.IndianJPsychiatry_526_18 |pmid=30745684 |pmc=6343421 |doi-access=free }}</ref>

== Epidemiology ==
[[File:Obsessive-compulsive disorder world map - DALY - WHO2004.svg|thumb|upright=1.35|Age-standardized [[disability-adjusted life year]] estimated rates for obsessive-compulsive disorder per 100,000 inhabitants in 2004{{Div col|small=yes|colwidth=9em}}
{{legend|#b3b3b3|no data}}
{{legend|#ffff65|<45}}
{{legend|#fff200|45–52.5}}
{{legend|#ffdc00|52.5–60}}
{{legend|#ffc600|60–67.5}}
{{legend|#ffb000|67.5–75}}
{{legend|#ff9a00|75–82.5}}
{{legend|#ff8400|82.5–90}}
{{legend|#ff6e00|90–97.5}}
{{legend|#ff5800|97.5–105}}
{{legend|#ff4200|105–112.5}}
{{legend|#ff2c00|112.5–120}}
{{legend|#cb0000|>120}}
{{div col end}}]]
Obsessive–compulsive disorder affects about 2.3% of people at some point in their life, with the yearly rate about 1.2%.<ref name="Good2014" /> OCD occurs worldwide.<ref name="DSM52" /> It is unusual for symptoms to begin after the age of 35 and half of people develop problems before 20.<ref name="NIH20152" /><ref name="DSM52" /> Males and females are affected about equally.<ref name="NIH20152" /> However, there is an earlier age for onset for males than females.<ref>{{Cite web |date=September 2022 |publisher=National Institute for Mental Health |title=Obsessive-Compulsive Disorder (OCD) |url=https://www.nimh.nih.gov/health/topics/obsessive-compulsive-disorder-ocd#:~:text=Obsessive%2Dcompulsive%20disorder%20(OCD),to%20repeat%20over%20and%20over. |access-date=2023-03-15}}</ref>


== History ==
[[Philosophy:Plutarch|Plutarch]], an [[Philosophy:Ancient Greek philosophy|ancient Greek philosopher]] and historian, [[Philosophy:Mental illness in ancient Rome|describes]] an ancient Roman man who possibly had scrupulosity, which could be a symptom of OCD or [[Medicine:Obsessive–compulsive personality disorder|OCPD]]. This man is described as "turning pale under his crown of flowers," praying with a "faltering voice," and scattering "incense with trembling hands."<ref>{{Cite book | vauthors = Summers J, Sinnott-Armstrong W |chapter=Obsessive Compulsive Disorder: A Little History |title=Clean Hands: Philosophical Lessons from Scrupulosity |publisher=Oxford University Press |year=2019 |isbn=978-019-005-869-2 |page=19}}</ref><ref>{{Cite book | vauthors = Friedrich P |url=https://books.google.com/books?id=cnekCgAAQBAJ&pg=PT33 |title=The Literary and Linguistic Construction of Obsessive-Compulsive Disorder: No Ordinary Doubt |date=2016-04-29 |publisher=Springer |isbn=978-1-137-42733-5 |language=en}}</ref><ref>{{cite book | vauthors = Plutarch | title = Selected Lives and Essays | publisher = Classics Club | date = 1951 | page = 375 }}</ref>

In the 7th century AD, John Climacus records an instance of a young [[Philosophy:Monk|monk]] plagued by constant and overwhelming "temptations to [[Religion:Blasphemy|blasphemy]]" consulting an older monk, who told him: "My son, I take upon myself all the sins which these temptations have led you, or may lead you, to commit. All I require of you is that for the future you pay no attention to them whatsoever."<ref name="Osborn1998">{{Cite book | vauthors = Osborn I |url=https://books.google.com/books?id=WVgTAAAAQBAJ&q=Obsessive+Compulsive+Disorder+in+antiquity&pg=PA210 |title=Tormenting Thoughts and Secret Rituals: The Hidden Epidemic of Obsessive-Compulsive Disorder |date=1998 |publisher=Dell Publishing |isbn=978-0-440-50847-2 |location=New York City, New York}}</ref>{{rp|212}} ''[[Religion:The Cloud of Unknowing|The Cloud of Unknowing]]'', a [[Religion:Christians|Christian]] mystical text from the late 14th century, recommends dealing with recurring obsessions by attempting to ignore them, and, if that fails, to "cower under them like a poor wretch and a coward overcome in battle, and reckon it to be a waste of your time for you to strive any longer against them", a technique now known as [[Medicine:Emotional flooding|emotional flooding]].<ref name="Osborn1998" />{{rp|213}}

[[Biography:Abu Zayd al-Balkhi|Abu Zayd Al-Balkhi]], the 9th century Islamic polymath, was likely the first to classify OCD into different types and pioneer [[Medicine:Cognitive behavioral therapy|cognitive behavioral therapy]], in a fashion unique to his era and which was not popular in Greek medicine.<ref name=":18">{{Cite journal |last=Awaad |first=Rania |last2=Ali |first2=Sara |date=15 July 2015 |title=Obsessional Disorders in al-Balkhi's 9th century treatise: Sustenance of the Body and Soul |journal=Journal of Affective Disorders |volume=180 |doi=10.1016/j.jad.2015.03.003 |pmid=25911133}}</ref> In his medical treatise entitled ''Sustenance of the Body and Soul,'' Al-Balkhi describes obsessions particular to the disorder as "Annoying thoughts that are not real. These intrusive thoughts prevent enjoying life, and performing daily activities. They affect concentration and interfere with ability to carry out different tasks."<ref>{{Cite book |last=Al-Balkhi |first=A.Z. |title=Masālih al-Abdān Wa-al-Anfus |last2=Misri |first2=M |last3=al-Hayyat |first3=M |publisher=Ma'had al-Makhtūtāt al-'Arabīyah |year=2005 |location=Cairo |language=ar}}</ref> As treatment, Al-Balkhi suggests treating obsessive thoughts with positive thoughts and mind-based therapy.<ref name=":18" />

From the 14th to the 16th century in Europe, it was believed that people who experienced blasphemous, sexual or other obsessive thoughts were possessed by the [[Biography:Satan|devil]].<ref name="Aardema, F. 2007">{{Cite journal | vauthors = Aardema F, O'Connor K |year=2007 |title=The menace within: obsessions and the self |journal=Journal of Cognitive Psychotherapy |volume=21 |issue=3 |pages=182–197 |doi=10.1891/088983907781494573 |s2cid=143731458}}</ref><ref name="Osborn1998" />{{rp|213}} Based on this reasoning, treatment involved banishing the "evil" from the "possessed" person through [[Unsolved:Exorcism|exorcism]].<ref name="Jenike">{{cite book | vauthors = Jenike MA, Baer L, Minichiello WE | title = Obsessive Compulsive Disorders: Theory and Management | location = Littleton, MA | publisher = PSG Publishing | date = 1986 }}</ref><ref name="berrios">{{cite journal | vauthors = Berrios GE | title = Obsessive-compulsive disorder: its conceptual history in France during the 19th century | journal = Comprehensive Psychiatry | volume = 30 | issue = 4 | pages = 283–295 | year = 1989 | pmid = 2667880 | doi = 10.1016/0010-440x(89)90052-7 }}</ref> The vast majority of people who thought that they were possessed by the devil did not have hallucinations or other "spectacular symptoms" but "complained of anxiety, religious fears, and evil thoughts."<ref name="Osborn1998" />{{rp|213}} In 1584, a woman from Kent, {{wipe|England}}, named Mrs. Davie, described by a [[Social:Justice of the peace|justice of the peace]] as "a good wife", was nearly burned at the stake after she confessed that she experienced constant, unwanted urges to murder her family.<ref name="Osborn1998" />{{rp|213}}

The English term ''obsessive–compulsive'' arose as a translation of [[Social:German language|German]] ''Zwangsvorstellung'' (''obsession'') used in the first conceptions of OCD by Karl Westphal. Westphal's description went on to influence Pierre Janet, who further documented features of OCD.<ref name="Sadock" /> In the early 1910s, [[Biography:Sigmund Freud|Sigmund Freud]] attributed obsessive–compulsive behavior to unconscious conflicts that manifest as symptoms.<ref name="Jenike" /> Freud describes the clinical history of a typical case of "touching phobia" as starting in early childhood, when the person has a strong desire to touch an item. In response, the person develops an "external prohibition" against this type of touching. However, this "prohibition does not succeed in abolishing" the desire to touch; all it can do is repress the desire and "force it into the unconscious."<ref>{{Cite book | vauthors = Freud S |title=Totem and Taboo:Some Points of Agreement between the Mental Lives of Savages and Neurotics |title-link=Totem and Taboo:Some Points of Agreement between the Mental Lives of Savages and Neurotics |publisher=W. W. Norton & Company |translator-last1 = Strachey |translator-first1 = J | name-list-style = vanc |year=1950 |isbn=978-0-393-00143-3 |location=New York | page = 29 }}</ref> Freudian [[Social:Psychoanalysis|psychoanalysis]] remained the dominant treatment for OCD until the mid-1980s, even though medicinal and therapeutic treatments were known and available, because it was widely thought that these treatments would be detrimental to the effectiveness of the [[Medicine:Psychotherapy|psychotherapy]].<ref name="Osborn1998" />{{rp|210–211}} In the mid-1980s, this approach changed, and practitioners began treating OCD primarily with medicine and practical therapy rather than through psychoanalysis.<ref name="Osborn1998" />{{rp|210}}

One of the first successful treatments of OCD, [[Philosophy:Exposure therapy|exposure and response prevention]], emerged during the 1960s, when psychologist Vic Meyer exposed two hospitalized patients to anxiety-inducing situations while preventing them from performing any compulsions. Eventually, both patients' anxiety level dropped  to manageable levels. Meyer devised this procedure from his analysis of [[Philosophy:Extinction (psychology)|fear extinguishment]] in animals via [[Philosophy:Flooding (psychology)|flooding]].<ref>{{Cite journal |last=Meyer |first=Vic |date=1966 |title=Modification of expectations in cases with obsessional rituals |journal=Behaviour Research and Therapy |volume=4 |issue=4 |pages=273–280 |doi=10.1016/0005-7967(66)90023-4 |pmid=5978682}}</ref> The success of ERP clinically and scientifically has been summarized as "spectacular" by prominent OCD researcher Stanley Rachman decades following Meyer's creation of the method.<ref name=":22">{{Cite web |title=Behavior Therapy for OCD: Its Origin |url=http://www.ocdhistory.net/20thcentury/behaviortherapy.html}}</ref>

In 1967, psychiatrist Juan José López-Ibor reported that the drug [[Chemistry:Clomipramine|clomipramine]] was effective in treating OCD. Many reports of its success in treatment followed, and several studies had confirmed its effectiveness by the 1980s.<ref>{{Cite book |last=Osborn |first=Ian |title=Tormenting Thoughts and Secret Rituals: The Hidden Epidemic of Obsessive-Compulsive Disorder |publisher=Dell Publishing |year=1999 |isbn=978-0-440-50847-2 |location=New York}}</ref><ref name="ocdhistory.net">{{Cite web |title=The history of obsessive-compulsive disorder |url=https://ocdhistory.net/20thcentury/new_meds.html |access-date=2023-11-04 |website=ocdhistory.net}}</ref> However, clomipramine was subsequently displaced by new [[Chemistry:Selective serotonin reuptake inhibitor|SSRIs]] developed in the 1970s, such as [[Chemistry:Fluoxetine|fluoxetine]] and [[Chemistry:Sertraline|sertraline]], which were shown to have less side effects.<ref name="NEJM2014" /><ref name="ocdhistory.net"/>

Obsessive-compulsive symptoms worsened during the early stages of the COVID-19 pandemic, particularly for individuals with contamination-related OCD.<ref>{{cite journal |last1=Guzick |first1=Andrew G. |last2=Candelari |first2=Abigail |last3=Wiese |first3=Andrew D. |last4=Schneider |first4=Sophie C. |last5=Goodman |first5=Wayne K. |last6=Storch |first6=Eric A. |title=Obsessive–Compulsive Disorder During the COVID-19 Pandemic: a Systematic Review |journal=Current Psychiatry Reports |date=November 2021 |volume=23 |issue=11 |page=71 |doi=10.1007/s11920-021-01284-2|pmid=34613498 |pmc=8493778 |doi-access=free }}</ref>

=== Notable cases ===
John Bunyan (1628–1688), the author of ''[[Unsolved:The Pilgrim's Progress|The Pilgrim's Progress]]'', displayed symptoms of OCD (which had not yet been named). During the most severe period of his condition, he would mutter the same phrase over and over again to himself while rocking back and forth.<ref name="Osborn1998" />{{rp|53–54}} He later described his obsessions in his autobiography ''Grace Abounding to the Chief of Sinners'', stating, "These things may seem ridiculous to others, even as ridiculous as they were in themselves, but to me they were the most tormenting cogitations."<ref name="Osborn1998" />{{rp|53–54}} He wrote two pamphlets advising those with similar anxieties.<ref name="Osborn1998" />{{rp|217–218}} In one of them, he warns against indulging in compulsions: "Have care of putting off your trouble of spirit in the wrong way: by promising to reform yourself and lead a new life, by your performances or duties".<ref name="Osborn1998" />{{rp|217–218}}

British poet, essayist and [[Social:Lexicography|lexicographer]] Samuel Johnson (1709–1784) also had OCD. He had elaborate rituals for crossing the thresholds of doorways, and repeatedly walked up and down staircases counting the steps.<ref>{{Cite web |title=Samuel Johnson (1709–1784): A Patron Saint of OCD? | vauthors = Penzel F | work = International OCD Foundation |url=http://westsuffolkpsych.homestead.com/Johnson.html |archive-url=https://web.archive.org/web/20050618085836/http://westsuffolkpsych.homestead.com/Johnson.html |archive-date= 18 June 2005 | access-date=29 November 2013 | via = Westsuffolkpsych.homestead.com}}</ref><ref name="Osborn1998" />{{rp|54–55}} He would touch every post on the street as he walked past, only step in the middles of paving stones, and repeatedly perform tasks as though they had not been done properly the first time.<ref name="Osborn1998" />{{rp|55}}

The "Rat Man", real name Ernst Lanzer, a notable patient of [[Biography:Sigmund Freud|Sigmund Freud]], suffered from what was then called "obsessional neurosis". Lanzer's illness was characterised most famously by a pattern of distressing intrusive thoughts in which he feared that his father or a female friend would be subjected to a purported Chinese method of [[Philosophy:Torture|torture]] in which rats would be encouraged to gnaw their way out of a victim's body by a hot poker.<ref>{{cite web |last1=Waude |first1=Adam |title=Rat Man Case Study: Sigmund Freud's Search For The Cause Of One Man's Obsessive Thoughts. |url=https://www.psychologistworld.com/freud/rat-man-case-study |website=www.psychologistworld.com |language=en |date=29 March 2016}}</ref>

American aviator and filmmaker [[Biography:Howard Hughes|Howard Hughes]] is known to have had OCD, primarily an obsessive fear of germs and contamination.<ref>{{Cite web | vauthors = Dittmann M |date=July–August 2005 |title=Hughes's germ phobia revealed in psychological autopsy |url=http://www.apa.org/monitor/julaug05/hughes.aspx |url-status=live |archive-url=https://web.archive.org/web/20150105071029/http://www.apa.org/monitor/julaug05/hughes.aspx |archive-date=5 January 2015 |access-date=9 January 2015 |website=American Psychological Association}}</ref> Friends of Hughes have also mentioned his obsession with minor flaws in clothing.<ref>{{Cite journal | vauthors =  Dittmann M |date=July–August 2005 |title=Hughes's germ phobia revealed in psychological autopsy |url=http://www.apa.org/monitor/julaug05/hughes.html |url-status=live |journal=Monitor on Psychology |volume=36 |issue=7 |archive-url=https://web.archive.org/web/20081229051558/http://www.apa.org/monitor/julaug05/hughes.html |archive-date=29 December 2008}}</ref> This was conveyed in ''The Aviator'' (2004), a film biography of Hughes.<ref name="MGHOCD">{{Cite web | vauthors = Chosak A |date=12 October 2012 |title=The Aviator: A real-life portrayal of OCD in the media |url=https://mghocd.org/the-aviator-ocd-in-the-media/ |url-status=live |archive-url=https://web.archive.org/web/20150222164535/https://mghocd.org/the-aviator-ocd-in-the-media/ |archive-date=22 February 2015 |access-date=9 January 2015 |website=Massachusetts General Hospital OCD and Related Disorders Program}}</ref>

English singer-songwriter George Ezra has openly spoken about his life-long struggle with OCD, particularly [[Medicine:Primarily obsessional obsessive–compulsive disorder|primarily obsessional obsessive–compulsive disorder]] (Pure O).<ref>{{Cite news |date=31 August 2020 |title=George Ezra opens up about OCD struggle |work=BBC News |url=https://www.bbc.com/news/entertainment-arts-53950320#:~:text=George%20Ezra%20says%20he%20is,physical%20actions%20to%20relieve%20them.&text=Discovering%20the%20condition%20existed%20made,less%20alone%2C%22%20he%20added.}}</ref>

World renowned Swedish climate activist Greta Thunberg is also known to have OCD, among other mental health conditions.<ref>{{Cite web |date=24 February 2020 |title=Greta Thunberg was nearly hospitalised due to disordered eating, says mother |url=https://www.independent.co.uk/life-style/health-and-families/greta-thunberg-aspergers-eating-disorder-malena-ernman-interview-a9355201.html |website=Independent.co.uk}}</ref>

American actor James Spader has also spoken about his OCD. In 2014, when interviewed for ''Rolling Stone'' he said: "I'm obsessive-compulsive. I have very, very strong obsessive-compulsive issues. I'm very particular. ... It's very hard for me, you know? It makes you very addictive in behavior, because routine and ritual become entrenched. But in work, it manifests itself in obsessive attention to detail and fixation. It serves my work very well: Things don't slip by. But I'm not very easygoing.<ref>{{Cite magazine |last=Goldman |first=Andrew |date=21 April 2014 |title=James Spader: The Strangest Man on TV |url=https://www.rollingstone.com/tv/tv-news/james-spader-the-strangest-man-on-tv-173892/ |magazine=Rolling Stone |access-date=10 July 2023}}</ref>

In 2022 the president of Chile Gabriel Boric stated that he had OCD, saying: "I have an obsessive–compulsive disorder that's completely under control. Thank God I've been able to undergo treatment and it doesn't make me unable to carry out my responsibilities as the President of the Republic."<ref>{{cite web |url=https://www.youtube.com/watch?v=lXNsCwFHNH8 |title=EXCLUSIVE: Chile's President On Why He's Open About His OCD |publisher=Amanpour and Company |date=26 September 2022 |via=[[Company:YouTube|YouTube]] |access-date=10 July 2023}}</ref>

In a documentary released in 2023, David Beckham shared details about his compelling cleaning rituals, need for symmetry in the fridge, and the impact of OCD on his life.<ref>{{cite web |last1=Banfield-Nwachi |first1=Mabel |title=David Beckham reveals impact of OCD in new documentary |url=https://www.theguardian.com/football/2023/apr/28/david-beckham-ocd-obsessive-compulsive-disorder-netflix-documentary |website=The Guardian |date=28 April 2023}}</ref>

== Society and culture ==
[[File:BFRB.Ribbbon.jpg|thumb|right|upright=0.8|This ribbon represents trichotillomania and other body-focused repetitive behaviors.]]

===Art, entertainment and media===
Movies and television shows may portray idealized or incomplete representations of disorders such as OCD.<ref>{{Cite journal |last1=Fennell |first1=Dana |last2=Boyd |first2=Michael |date=2014-09-02 |title=Obsessive-Compulsive Disorder in the Media |url=https://www.tandfonline.com/doi/full/10.1080/01639625.2013.872526 |journal=Deviant Behavior |language=en |volume=35 |issue=9 |pages=669–686 |doi=10.1080/01639625.2013.872526 |s2cid=145735144 |issn=0163-9625}}</ref> Compassionate and accurate literary and on-screen depictions may help counteract the potential stigma associated with an OCD diagnosis, and lead to increased public awareness, understanding and sympathy for such disorders.<ref>{{Cite web |title=Don't Be Afraid of the Word "Disorder" |url=https://beyondocd.org/expert-perspectives/articles/dont-be-afraid-of-the-word-disorder |access-date=2020-11-11 |website=Beyond OCD |language=en-US}}</ref><ref name="Goldberg">{{Cite book | vauthors = Goldberg FR |url=http://secure.ce4alliance.com/articles/101188/Turn_Box_Office_Movies-CE%5B1%5D.pdf |title=Turn box office movies into mental health opportunities: A literature review and resource guide for clinicians and educators |date=2007 |publisher=Beneficial Film Guides, Inc. |page=8 |access-date=17 February 2010 |archive-url=https://web.archive.org/web/20110708130111/http://secure.ce4alliance.com/articles/101188/Turn_Box_Office_Movies-CE%5B1%5D.pdf |archive-date=8 July 2011 }}</ref>
* The play and film adaptations of'' The Odd Couple'' based around the character of Felix, who shows some of the common symptoms of OCD.<ref>{{Cite web |title=Felix Unger from The Odd Couple|website=CharacTour|url=https://www.charactour.com/hub/characters/view/Felix-Unger.The-Odd-Couple}}</ref>
* In the film ''As Good as It Gets'' (1997), actor Jack Nicholson portrays a man with OCD who performs ritualistic behaviors that disrupt his life.<ref name="mghocd.org">{{Cite web | vauthors = Berman N |date=5 October 2012 |title=Is This 'As Good as It Gets?': Popular Media's Representation of OCD |url= https://mghocd.org/as-good-as-it-gets/ |url-status=live |archive-url= https://web.archive.org/web/20150222163353/https://mghocd.org/as-good-as-it-gets/ |archive-date=22 February 2015 |access-date=9 January 2015 |website=Massachusetts General Hospital OCD and Related Disorders Program}}</ref>
* The film ''Matchstick Men'' (2003) portrays a con man named Roy (Nicolas Cage) with OCD who opens and closes doors three times while counting aloud before he can walk through them.<ref>{{Cite web | vauthors = Almeida J |title=Royal College of Psychiatrists, Discover Psychiatry, Minds on Film Blog, Matchstick Men |url=http://www.rcpsych.ac.uk/mentalhealthinfo/mindsonfilmblog/matchstickmen.aspx |archive-url=https://web.archive.org/web/20150222173938/http://www.rcpsych.ac.uk/mentalhealthinfo/mindsonfilmblog/matchstickmen.aspx |archive-date=22 February 2015 |access-date=14 January 2015 |website=Royal College of Psychiatrists}}</ref>
* In the television series ''Monk'' (2002–2009), the titular character Adrian Monk fears both human contact and dirt.<ref>{{Cite news | vauthors = Stewart S |date=16 September 2007 |title=Happy to Be Neurotic, at Least Once a Week |work=The New York Times |url=https://www.nytimes.com/2007/09/16/arts/television/16stew.html |url-status=live |access-date=8 December 2008 |archive-url=https://web.archive.org/web/20081211174041/http://www.nytimes.com/2007/09/16/arts/television/16stew.html |archive-date=11 December 2008}}</ref><ref>{{Cite web |last=Anxiety Disorders Association of America |title=What Is OCD? |url=http://www.usanetwork.com/series/monk/community/ocd/index.html |archive-url=https://web.archive.org/web/20081217130053/http://www.usanetwork.com/series/monk/community/ocd/index.html |archive-date=17 December 2008 |access-date=8 December 2008 |website=USA Network}}</ref>
* In the novel ''Turtles All the Way Down'' (2017) by [[Biography:John Green|John Green]], teenage main character Aza Holmes struggles with OCD that manifests as a fear of the human microbiome. Throughout the story, Aza repeatedly opens an unhealed [[Medicine:Callus|callus]] on her finger to drain out what she believes are pathogens. The novel is based on Green's own experiences with OCD. He explained that ''Turtles All the Way Down'' is intended to show how "most people with chronic mental illnesses also live long, fulfilling lives".<ref>{{Cite news | vauthors = Flood A |date=14 October 2017 |title=John Green: 'Having OCD is an ongoing part of my life' |work=The Guardian |url=https://www.theguardian.com/books/2017/oct/14/john-green-turtles-all-the-way-down-ocd-interview |access-date=21 September 2019}}</ref>
* The British TV series ''Pure'' (2019) stars Charly Clive as a 24-year-old Marnie who is plagued by disturbing sexual thoughts, as a kind of [[Medicine:Primarily obsessional obsessive compulsive disorder|primarily obsessional obsessive compulsive disorder]].<ref>{{Cite news | vauthors = Mangan L |date=30 January 2019 |title=Pure review – a masterly comedy about sex and mental health |work=The Guardian |url=https://www.theguardian.com/tv-and-radio/2019/jan/30/pure-o-ocd-review-brave-brilliant-miracle-mental-health-sex |access-date=7 April 2021}}</ref>

== Research ==
The naturally occurring sugar [[Chemistry:Inositol|inositol]] has been suggested as a treatment for OCD.<ref>{{cite journal | vauthors = Camfield DA, Sarris J, Berk M | title = Nutraceuticals in the treatment of obsessive compulsive disorder (OCD): a review of mechanistic and clinical evidence | journal = Progress in Neuro-Psychopharmacology & Biological Psychiatry | volume = 35 | issue = 4 | pages = 887–895 | date = June 2011 | pmid = 21352883 | doi = 10.1016/j.pnpbp.2011.02.011 | s2cid = 30024004 }}</ref>

[[Biology:Μ-opioid receptor|μ-Opioids]] agonists, such as [[Chemistry:Hydrocodone|hydrocodone]] and [[Chemistry:Tramadol|tramadol]], may improve OCD symptoms.<ref name="Davidson‌ 03">{{cite journal | vauthors = Davidson J, Bjorgvinsson T | title = Current and potential pharmacological treatments for obsessive-compulsive disorder | journal = Expert Opinion on Investigational Drugs | volume = 12 | issue = 6 | pages = 993–1001 | date = June 2003 | pmid = 12783603 | doi = 10.1517/13543784.12.6.993 | s2cid = 35971588 }}</ref> Administration of opiate treatment may be contraindicated in individuals concurrently taking [[Biology:CYP2D6|CYP2D6]] inhibitors such as [[Chemistry:Fluoxetine|fluoxetine]] and [[Chemistry:Paroxetine|paroxetine]].<ref name="Focus 07">{{Cite journal | vauthors = Koran LM |year=2007 |title=Obsessive-Compulsive Disorder: An Update for the Clinician |journal=Focus |issue=5 |page=3}}</ref>

Much current research is devoted to the therapeutic potential of the agents that affect the release of the neurotransmitter glutamate or the binding to its receptors. These include [[Chemistry:Riluzole|riluzole]], [[Chemistry:Memantine|memantine]], [[Chemistry:Gabapentin|gabapentin]], N-acetylcysteine, [[Biology:Topiramate|topiramate]] and [[Chemistry:Lamotrigine|lamotrigine]].<ref name="Wu2012">{{cite journal | vauthors = Wu K, Hanna GL, Rosenberg DR, Arnold PD | title = The role of glutamate signaling in the pathogenesis and treatment of obsessive-compulsive disorder | journal = Pharmacology, Biochemistry, and Behavior | volume = 100 | issue = 4 | pages = 726–735 | date = February 2012 | pmid = 22024159 | pmc = 3437220 | doi = 10.1016/j.pbb.2011.10.007 }}</ref> Research on the potential for other supplements, such as milk thistle, to help with OCD and various neurological disorders, is ongoing.<ref>{{Cite journal |last1=Ranjan |first1=Shovit |last2=Gautam |first2=Akash |date=2023 |title=Pharmaceutical prospects of Silymarin for the treatment of neurological patients: an updated insight |journal=Frontiers in Neuroscience |volume=17 |doi=10.3389/fnins.2023.1159806 |pmid=37274201 |pmc=10232807 |issn=1662-453X |doi-access=free }}</ref>

== Other animals ==

== References ==
{{reflist}}

== External links ==
* {{Curlie|Health/Mental_Health/Disorders/Anxiety/Obsessive-Compulsive/}}
* [https://www.nimh.nih.gov/health/topics/obsessive-compulsive-disorder-ocd/ National Institute Of Mental Health]
* [https://www.psychiatry.org/patients-families/ocd/what-is-obsessive-compulsive-disorder American Psychiatric Association]
* [http://www.div12.org/psychological-treatments/disorders/obsessive-compulsive-disorder/ APA Division 12 treatment page for obsessive-compulsive disorder]
* {{Cite book | vauthors = Davis LJ |url=https://archive.org/details/obsessionhistory00davi_0 |title=Obsession: A History |publisher=University of Chicago Press |year=2008 |isbn=978-0-226-13782-7}}

{{Medical resources
| DiseasesDB      = 33766
| DiseasesDB_mult =
| ICD11           = {{ICD11|6B20}}
| ICD10           = {{ICD10|F42}}
| ICD9            = {{ICD9|300.3}}
| ICDO            =
| OMIM            = 164230
| MedlinePlus     = 000929
| eMedicineSubj   = article
| eMedicineTopic  = 287681
| eMedicine_mult  =
| MeshID          = D009771
}}
{{Mental and behavioral disorders |selected = neurotic }}
{{Obsessive–compulsive disorder}}
{{OCD pharmacotherapies}}

{{DEFAULTSORT:Obsessive-compulsive disorder}}
[[Category:Anxiety disorders]]
[[Category:Wikipedia medicine articles ready to translate]]

{{Sourceattribution|Obsessive–compulsive disorder}}