Obsessive-Compulsive Disorder: Diagnosis, Clinical Features, Nosology, and Epidemiology.

Obsessive-compulsive disorder (OCD) is characterized by time-consuming, distressing, or impairing obsessions and compulsions. Obsessions are recurrent, persistent, and intrusive thoughts, urges, or images. Compulsions are repetitive and often ritualized behaviors or mental acts performed to manage obsession-related distress or prevent harm. OCD affects 1% to 3% of the population, typically begins during adolescence or early adulthood, and can have a chronic or deteriorating course in the absence of effective treatment.