738 BIOL PSYCHIATRY 1991 ;29:738-744 Whole Blood Serotonin in Juvenile Obsessive-Compulsive Disorder Gregory L. Hanna, Arthur Yuwiler, and Dennis P. Cantwell 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 ~nctioning 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 OCO. Introduction Obsessive-compulsive disorder (OCD) is one of the more chronic and prevalent conditions in psychiatry (Goodwin et al 1969; Karno et al 1988). It appears to be similar in children and adults in its clinical presentation and response to pharmacological treatment (Rapoport 1986; Flament et al 1985; Leonard et al 1989). The therapeutic response to serotonergic antidepressants has sugge3ted that a serotonergic dysfunction is involved in the patho- physiology of OCD, but this response does not necessarily implicate a primary serotonergic abnormality in OCD (Murphy et al 1989). Few studies of OCD have measured serotonin (5-hydroxytryptamine, 5-HT) in blood platelets or 5-hydroxyindoleacetic acid (5-HIAA), the principal 5-HT metabolite in cerebrcspinal fluid (CSF). Yuryura-Tobias et al (1977) reported that whole blood 5-HT concentrations were significantly lower in OCD patients than in normal controls. In contrast, Ha,neat et a! (1987) found no difference between juvenile OCD patients and normal controls in platelet 5-HT levels. They found a significant negative correlation, however, between platelet 5- HI" content and severity of obsessive-compulsive symptoms, lnsel et al (1985) reported that CSF 5-HIAA levels were significantly higher in 8 OCD patients than in 23 controls. ...I~ tuu~.,,... 1 2 r g e r ~ ' " r "''~,e~mnioc h~,u~,,~r, ......... O.~r~ tnntionte ~nd nnrm~l ~-nntro! s did nnt dlffpr in ~...~.. 5-HIAA levels (Thoren et al 1980; Lydiard et al 1990). From the Department of Psychiatry and Biobehavioral Sciences, School of Medicine, U:.iversity of California at Los Angeles (GLH, AY, DPC) and the Neurobiochemistry Laboratory, Brentwood Division, West Los Angeles Veterans Administration Medical Center, Los Angeles, CA (AY). Address reprint requests to Dr. Gregory L. Hanna, UCLA Neuropsychiatric Institute, 760 Westwood Plaza, LOs Angeles, CA 90024. Received July 20, 1990; revised November 13, 1990. © 1991 Society of Biological Psychiatry 0006-3223/91/$03.50