Obsessive-Compulsive Disorder - Causes

The cause of obsessive-compulsive disorder has not yet been found. Many researchers believe that it may be inherited. If one person in a family has OCD, there is a 25 percent chance that another family member will also have the condition. Stress and other psychological factors may also contribute to the development of OCD.

One popular theory is that OCD is caused by low levels of seratonin (pronounced sihr-uh-TOE-nun), a neurotransmitter. Neurotransmitters are chemicals that occur in the brain. They are responsible for delivering electrical signals from one nerve cell to another and help control many of the mental activities that occur in the brain.

Some researchers think that OCD develops when the brain produces too much or too little of some particular neurotransmitter. In such a case, nerve messages cannot travel smoothly from one part of the brain to another. They may begin to recycle—that is, to travel again and again across the same set of nerves. This constant repetition of nerve messages might be responsible for the repetitive behavior characteristic of compulsions.

Another theory is that OCD may be related to childhood episodes of strep throat (see strep throat entry), a bacterial infection. In some children, strep throat antibodies attack a certain part of the brain. Antibodies are chemicals produced by the immune system. Their job is to fight off infections. But antibodies can sometimes cause damage to the body itself. Researchers think that damage to the brain caused by strep throat antibodies may lead to obsessions and compulsions such as fear of germs and excessive hand washing. Some children with OCD have benefited from treatment with antibiotics.