Serotonin and treatment in obsessive-compulsive disorder.

Recognized since the Middle Ages, and clearly described for more than 100 years, obsessive-compulsive disorder (OCD) continues to intrigue and challenge mental health professionals. Recent evidence has implicated dysfunctional serotonergic neurotransmission in OCD. This review summarizes the evidence favoring a serotonergic hypothesis for OCD followed by a more detailed discussion of the implications the hypothesis holds for treatment.