Episodic and chronic obsessive-compulsive disorder.

Several lines of evidence support the concept of obsessive-compulsive disorder (OCD) as a heterogeneous illness. Using a range of factors such as demographic, psychosocial, and clinical variables, we compared OCD patients with chronic (n = 55) versus episodic (n = 46) courses of illness. Patients were evaluated monthly for 1 year while receiving no treatment. Significant differences in sex ratio, age at onset of the disorder, illness duration, type of symptoms, and familial history were found between the two groups. These findings are consistent with the concept of OCD as a heterogeneous disorder. Patients with an episodic course of the disorder may be a distinct subgroup within the whole group of obsessive-compulsive patients.