Obsessive-compulsive disorder (OCD) is a mental health condition characterized by features called obsessions and compulsions. Obsessions are intrusive thoughts, mental images, or urges to perform specific actions. While the particular obsessions vary widely, they often include fear of illness or contamination; a desire for symmetry or getting things "just right;" or intrusive thoughts involving religion, sex, or aggression. Compulsions consist of the repetitive performance of certain actions, such as checking or verifying, washing, counting, arranging, acting out specific routines, or seeking assurance. These behaviors are performed to relieve anxiety, rather than to seek pleasure as in other compulsive behaviors like gambling, eating, or sex.
While almost everyone experiences obsessive feelings and compulsive behaviors occasionally or in particular contexts, in OCD they take up more than an hour a day and cause problems with work, school, or social life. People with OCD generally experience anxiety and other distress around their need to accommodate their obsessions or compulsions.
About half the time, OCD becomes evident in childhood or adolescence, and most other cases appear in early adulthood. It is unusual for OCD to start after age 40. It tends to appear earlier in males, but by adulthood it is slightly more common in females. Affected individuals can experience periods when their symptoms increase or decrease in severity, but the condition usually does not go away completely.
Some people with OCD have additional mental health disorders such as generalized anxiety, depression, phobias, panic disorders, or schizophrenia. OCD can also occur in people with other neurological conditions such as Tourette syndrome and similar disorders, traumatic brain injury, stroke, or dementia.
OCD is a common condition, occurring in about 2 percent of the population.
The cause of OCD is unknown. Researchers are investigating whether the condition might involve changes in the brain's response to chemical messengers (neurotransmitters) such as serotonin or dopamine. Problems with regulating the activity of and interaction between various parts of the brain are also thought to contribute to the condition.
Variations in certain genes that provide instructions for proteins that react to or transport serotonin have been associated with an increased risk of OCD. Variations in other genes involved in communication in the brain may also be associated with the condition. However, not all people with OCD have an associated variation, and not all people with the variations will develop OCD.
In addition to genetic factors, researchers are studying environmental factors that might contribute to OCD, including complications during pregnancy or childbirth and stressful life events. However, none have been conclusively associated with this disorder. It seems likely that environmental conditions interact with genetic factors to determine the overall risk of developing OCD.
The inheritance pattern of OCD is unclear. Overall, the risk of developing this condition is greater for first-degree relatives of affected individuals (such as siblings or children) as compared to the general public. For unknown reasons, the risk of inheriting the disorder appears to be higher in some families than in others. However, most people who have a close relative with OCD will not develop the condition themselves.