Obsessive-compulsive disorder (OCD) is a common mental illness in which people feel burdened by unwanted thoughts or forced to repeat troublesome actions. Unwanted thoughts, called obsessions, often include unreasonable fear of dirt or germs. Another common obsession involves fear of losing control and hurting oneself or others. Many patients also feel a need to perform repeated actions, called compulsions, to prevent harmful events. Some wash their hands excessively to avoid infection. Unreasonable repetition of everyday routines–for example, checking that faucets or stoves are turned off–is also common.
Most people have certain routines and habits that they find comforting. For example, a person may like to get dressed or prepare for bed in a certain way. But most people can change their routines when the need arises. People with obsessive-compulsive disorder feel trapped and unable to change, even though they know that their obsessions and compulsions are unrealistic.
Many experts believe that obsessive-compulsive disorder involves an imbalance in serotonin, one of the brain’s most important messenger chemicals. Doctors may treat the disorder with medicines that correct serotonin levels. People may also be helped by behavior therapy, which teaches patients ways to resist their unreasonable thoughts and actions.