PLATELET SEROTONIN TRANSPORTER IN CHILDREN AND ADOLESCENTS WITH OBSESSIVE-COMPULSIVE DISORDER OR TOURETTES-SYNDROME

Previous studies of serotonin transporter protein (5HTPR) indexed in p latelets by H-3-imipramine demonstrate reduction in children with como rbid obsessive-compulsive disorder (OCD) and Tourette's syndrome (TS). Objective: To use the 5HTPR selective ligand H-3-paroxetine and homog eneous diagnostic groups to reevaluate these findings. Method: Platele t kinetic binding parameters were evaluated using standard techniques from medication-free child and adolescent patients with OCD (n = 18), with TS (n = 10), and normal controls (n = 19). Results: Baseline bind ing capacity (B-max) was significantly reduced in patients with OCD (1 ,342 +/- 952 fmol/mg protein; p <.01) compared with normal controls (2 ,486 +/- 1309 fmol/mg) and TS patients (2,420 +/- 1,069 fmol/mg; p <.0 5). Among OCD patients who were subsequently treated on an open-label basis with selective serotonin reuptake inhibitor (SSRI), B-max values at baseline differentiated between responders (1,718 +/- 1,041 fmol/m g) and nonresponders (802 +/- 713 fmol/mg protein; p <.05). Response t o SSRI was greatest in patients with a positive family history of OCD. Among responders (n = 10), baseline Yale-Brown Obsessive Compulsive S cale and B-max were positively correlated (r=.76, p =.01), as was Clin ical Global Impression (r=.67, p=.03). Conclusions: Platelet 5HTPR cap acity (B-max) is reduced in children and adolescents with OCD, but not in those with TS. 5HTPR may be an indirect measure of basal serotoner gic tone.