What it is:

An anxiety disorder that causes a person to have unwanted thoughts and fears (obsessions) and to try to ease those fears with repeated acts (compulsions). Common obsessions are fear of dirt or germs, a need for order or symmetry, worry that a task has not been completed, fear of harming a loved one, or constantly thinking about certain sounds, images, words or numbers. Common compulsions are repeated cleaning or grooming, checking, ordering, counting or hoarding.

Many people have habits and traits that resemble OCD. But that's not the same thing. People with OCD cannot stop their obsessions and compulsions; they experience extreme fear and anxiety associated with them, and find that the repetitive thoughts and actions interfere with their lives.

Prevalence:

An estimated 2.2 million Americans age 18 and older, or about 1 percent of adults in any given year.

It affects men and women equally.

Treatment:

Medication and behavioral therapy, or a combination. Drugs that affect the availability of the brain chemical serotonin, such as Zoloft or Prozac, are often prescribed. Behavioral therapy encourages patients to confront the anxiety and resist the urge to respond with a compulsion.

For more information:

The National Institute of Mental Health, www.nimh.nih.gov/healthinformation/ocdmenu.cfm

The Obsessive Compulsive Foundation, www.ocfoundation.org, (203) 315-2190

The Anxiety Disorders Association of America, www.adaa.org, (301) 231-9350.

Brain Lock , by Jeffrey M. Schwartz, Regan Books, 1996.

Everything in its Place , by Marc Summers and Jeremy P. Tarcher, Putnam, 1999.

Freedom from Obsessive-Compulsive Disorder, by Jonathan Grayson, Penguin, 2003.

The OCD Workbook, by Bruce M. Hyman and Cherry Pedrick, New Harbor Publications, 2005.