Obsessive-compulsive disorder is an anxiety disorder in which people have thoughts, feelings, ideas, sensations (obsessions), or behaviors that make them feel driven to do something (compulsions). A person may have both obsessions and compulsions.

Obsessive-compulsive disorder (OCD) is more common than was once thought. Most people who develop it show symptoms by age 30.

There are several theories about the cause of OCD, but none have been confirmed. Some reports have linked OCD to head injury and infections. Several studies have shown that there are brain abnormalities in patients with OCD, but more research is needed.

About 20% of people with OCD have tics, which suggests the condition may be related to Tourette syndrome. However, this link is not clear.

• Obsessions or compulsions are not due to medical illness or drug use
• Obsessions or compulsions cause major distress or interfere with everyday life

An example of obsessive-compulsive disorder is excessive, repeated handwashing to ward off infection.

The person usually recognizes that the behavior is excessive or unreasonable.

Your own description of the behavior can help diagnose the disorder. A physical exam can rule out physical causes, and a psychiatric evaluation can rule out other mental disorders.

Questionnaires, such as the Yale-Brown Obsessive Compulsive Scale, can help diagnose OCD and track the progress of treatment.