Obsessive–compulsive disorder (OCD) is a mental and behavioral disorder in which a person has certain thoughts repeatedly (called "obsessions") and/or feels the need to perform certain routines repeatedly (called "compulsions") to an extent that generates distress or impairs general functioning. The person is unable to control either the thoughts or activities for more than a short period of time. Common compulsions include excessive hand washing, the counting of things, and checking to see if a door is locked. These activities occur to such a degree that the person's daily life is negatively affected, often taking up more than an hour a day. Most adults realize that the behaviors do not make sense. The condition is associated with tics, anxiety disorder, and an increased risk of suicide.

The cause is unknown. There appear to be some genetic components, with both identical twins more often affected than both non-identical twins. Risk factors include a history of child abuse or other stress-inducing event. Some cases have been documented to occur following infections. The diagnosis is based on the symptoms and requires ruling out other drug-related or medical causes. Rating scales such as the Yale–Brown Obsessive Compulsive Scale (Y-BOCS) can be used to assess the severity. Other disorders with similar symptoms include anxiety disorder, major depressive disorder, eating disorders, tic disorders, and obsessive–compulsive personality disorder.

Treatment may involve psychotherapy, such as cognitive behavioral therapy (CBT), and antidepressants, such as selective serotonin reuptake inhibitors (SSRIs) or clomipramine. CBT for OCD involves increasing exposure to fears and obsessions while preventing the compulsive behavior that would normally accompany the obsessions. Contrary to this, metacognitive therapy encourages the ritual behaviors in order to alter the relationship to one's thoughts about them. While clomipramine appears to work as well as do SSRIs, it has greater side effects and thus is typically reserved as a second-line treatment. Atypical antipsychotics may be useful when used in addition to an SSRI in treatment-resistant cases but are also associated with an increased risk of side effects. Without treatment, the condition often lasts decades.

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%. It is unusual for symptoms to begin after the age of 35, and half of people develop problems before 20. Males and females are affected about equally and OCD occurs worldwide. The phrase obsessive–compulsive is sometimes used in an informal manner unrelated to OCD to describe someone as being excessively meticulous, perfectionistic, absorbed, or otherwise fixated.

 

Note:   The above text is excerpted from the Wikipedia article Obsessive–compulsive disorder, which has been released under the GNU Free Documentation License.