Whole blood serotonin in juvenile obsessive-compulsive disorder.

Whole blood serotonin (5-HT) concentration was assessed in 16 children and adolescents with severe obsessive-compulsive disorder (OCD) and in 14 normal adolescent controls. There was no difference in blood 5-HT content between the OCD patients and the normal controls. However, the OCD patients with a family history of OCD had significantly higher blood 5-HT levels than did either the OCD patients without a family history of OCD or the normal controls. Blood 5-HT content was not associated with a history of major depressive disorder or chronic tic disorder. These preliminary results suggest that studies of serotonergic functioning in OCD may need to control for family history of OCD and that blood 5-HT may be a useful biochemical measure in family-genetic studies of OCD.