Snapshot A 25-year-old woman presents to clinic for hair loss. She had been dealing with hair loss for a few months and reports an itching in her scalp. She is worried about an infestation of her hair and often picks at her scalp. She is preoccupied with these thoughts, which occur almost every hour, and has sought care at multiple doctors, dermatologists, and even exterminators. No infestation has been identified on her scalp. On exam, she has multiple patches of hair loss, with varying lengths of hair growing from each patch, and negative hair-pull test. She is referred to psychiatry for suspected obsessive-compulsive disorder. Introduction Overview obsessive-compulsive disorder is characterized by obsessive intrusive thoughts, sensations, or feelings that may be relieved by repetitive compulsive mental or physical actions treatment is usually cognitive behavioral therapy or medications Epidemiology Incidence common, with a lifetime prevalence of 1.7-4% prevalence increases by 1.5-2-fold during pregnancy Demographics males are more likely to have onset in adolescence and to have a comorbid tic disorder Risk factors family history ETIOLOGY Pathogenesis mechanism exact pathogenesis is unclear but research suggests that there are abnormalities in serotonin neurotransmission twin studies also show a genetic influence, although a genetic mutation has not been identified disorder is ego-dystonic behavior inconsistent with one's own beliefs and attitudes separates OCD from obsessive-compulsive personality disorder Associated conditions patients often have other psychiatric comorbidities, including mood and anxiety disorders Tourette disorder treat with risperidone Presentation Symptoms obsessions and compulsions often occupy hours a day and interfere with daily life recurrent and persistent intrusive thoughts (obsessions) common obsessions include fear of contamination, need for symmetry, unwanted sexual thoughts, and doubts causes anxiety and distress repetitive behaviors (compulsions) hand washing putting items in order checking and rechecking tasks Physical exam hand dermatitis related to excessive hand washing patchy hair loss related to compulsive hair pulling excoriations or prurigo nodules related to compulsive skin picking Studies Yale-Brown Obsessive Compulsive scale to evaluate range and severity of symptoms to monitor treatment response Differential Intrinsic atopic dermatitis key distinguishing factors treatment with topical steroids can help resolve rash treatment with cognitive behavioral therapy and control of compulsions may not result in resolution of rash Body dysmorphic disorder key distinguishing factors preoccupation with a perceived defect in one’s appearance, causing significant distress and dysfunction treatment with cognitive behavioral therapy Treatment Lifestyle cognitive behavioral therapy (CBT) indications all patients some patients may not need pharmacologic treatment with successful behavioral therapy Medical serotonin selective reuptake inhibitors (SSRIs) indications first-line often in addition to CBT tricyclic antidepressant indication second-line clomipramine antipsychotics indication used as augmentation therapy Complications Continued psychologic distress and functional impairment Prognosis Symptoms wax and wane, even with treatment