Introduction to Obsessive-Compulsive Disorder

What Causes Obsessive-Compulsive Disorder?

Obsessive-compulsive disorder (OCD) is a common psychological disorder that has been estimated to affect about 1% to 4% of people in the United States. The condition appears to affect men and women in about equal proportions and usually begins in childhood or early adulthood. Because many people with OCD are ashamed of their symptoms they are often reluctant to seek treatment and share information with their health care providers. The diagnosis of OCD may be delayed, therefore, for many years after the onset of symptoms. Most people in the United States who are diagnosed with OCD are in the 25-35 year age group.

Although the exact cause of obsessive-compulsive disorder (OCD) remains unknown, most experts agree that genetic predisposition is a major factor in many people who develop this disorder. Support for the genetic predisposition theory comes from studies involving monozygotic twins which have found that if one of the twins has symptoms consistent with OCD, the likelihood of the second twin also developing OCD is about 80%. Studies have also found that up-to 20% of first-degree relatives (i.e., children of a parent with OCD) will also develop the condition - a significantly higher prevalence rate of OCD than is found in the general population (1% to 4%).

In addition to genetic predisposition, in rare cases, obsessive-compulsive disorder (OCD) may be caused by other conditions including:

• Encephalitis - inflammation of the brain caused by a virus
• Infection with Group A beta-hemolytic streptococcus (usually in children)
• Tourette's syndrome - a nervous system disorder characterized by involuntary movements of the facial muscles and other areas of the body called tics and compulsive utterances of speech or grunts
• Head injury
• Developmental abnormalities involving certain parts of the brain such as the frontal lobe