An update on obsessive-compulsive disorder.

It is now recognized that obsessive-compulsive disorder (OCD) affects almost 3% of the world's population and is a major worldwide health problem. Much has been learned in the past 2 decades about the treatment of these disorders. Recent developments in neuroimaging techniques have led to a better understanding of the biology of OCD and the brain circuits that may be involved in the production of symptoms. The most effective treatment approaches, based on controlled data, are behavior therapy consisting of exposure and response prevention and specific medications. Although controversial, more invasive neurosurgical and neurostimulation approaches may hold some promise for severely disabled patients. Despite impressive research efforts, a small minority of patients remain refractory to treatment. Future clinical research should focus on this refractory group.