Obsessive–compulsive disorder (OCD) is a mental disorder in which an individual has intrusive thoughts (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. Obsessions are persistent unwanted thoughts, mental images, or urges that generate feelings of anxiety, disgust, or discomfort. Some common obsessions include fear of contamination, obsession with symmetry, the fear of acting blasphemously, sexual obsessions, and the fear of possibly harming others or themselves. 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, ordering, repeating, avoiding triggers, hoarding, neutralizing, seeking assurance, praying, and checking things. OCD can also manifest exclusively through mental compulsions, such as mental avoidance and excessive rumination. This manifestation is sometimes referred to as primarily obsessional obsessive–compulsive disorder. Compulsions occur often and typically take up at least one hour per day, impairing one's quality of life. 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. For this reason, thoughts and behaviors in OCD are usually considered egodystonic (inconsistent with one's ideal self-image). In contrast, thoughts and behaviors in obsessive–compulsive personality disorder (OCPD) are usually considered egosyntonic (consistent with one's ideal self-image), helping differentiate between OCPD and OCD. Although the exact cause of OCD is unknown, several regions of the brain have been implicated in its neuroanatomical model including the anterior cingulate cortex, orbitofrontal cortex, amygdala, and BNST. The presence of a genetic component is evidenced by the increased likelihood for both identical twins to be affected than both fraternal twins. Risk factors include a history of child abuse or other stress-inducing events such as during the postpartum period or after streptococcal infections. 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. Other disorders with similar symptoms include generalized anxiety disorder, major depressive disorder, eating disorders, tic disorders, body-focused repetitive behavior, and obsessive–compulsive personality disorder. Personality disorders are a common comorbidity, with schizotypal and OCPD having poor treatment response. The condition is also associated with a general increase in suicidality. The phrase obsessive–compulsive is sometimes used in an informal manner unrelated to OCD to describe someone as excessively meticulous, perfectionistic, absorbed, or otherwise fixated. However, the actual disorder can vary in presentation and individuals with OCD may not be concerned with cleanliness or symmetry. OCD is chronic and long-lasting with periods of severe symptoms followed by periods of improvement. Treatment can improve ability to function and quality of life, and is usually reflected by improved Y-BOCS scores. Treatment for OCD may involve psychotherapy, pharmacotherapy such as antidepressants or surgical procedures such as deep brain stimulation or, in extreme cases, psychosurgery. Psychotherapies derived from cognitive behavioral therapy (CBT) models, such as exposure and response prevention, acceptance and commitment therapy, and inference based-therapy, are more effective than non-CBT interventions. Selective serotonin reuptake inhibitors (SSRIs) are more effective when used in excess of the recommended depression dosage; however, higher doses can increase side effect intensity. Commonly used SSRIs include sertraline, fluoxetine, fluvoxamine, paroxetine, citalopram, and escitalopram. 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 clomipramine or atypical antipsychotic augmentation. 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. There is growing evidence to support the use of deep brain stimulation and repetitive transcranial magnetic stimulation for treatment-resistant OCD. Source: Wikipedia (en)