Platelet [3H]paroxetine binding in patients with OCD-related disorders.

The recently introduced notion of clinical conditions being related one to another, the spectrum concept, permits the testing of the involvement of serotonergic systems in a broad range of disorders tentatively linked to obsessive-compulsive disorder (OCD) for which no pathophysiological hypotheses yet exist. We therefore compared the binding of [3H]paroxetine ([3H]Par), a ligand that specifically labels the serotonin (5-HT) transporter, in platelets of drug-free outpatients suffering from various OCD-related disorders with binding in platelets of OCD patients and healthy subjects. Diagnoses were made according to DSM-IV criteria. The most frequent diagnosis was that of body dysmorphic disorder, followed by impulse control disorder, kleptomania, Tourette's syndrome and trichotillomania. Platelet membranes and [3H]Par binding were studied according to standardized protocols. The results, showing a similarly decreased density of [3H]Par binding sites in both patient groups as compared with healthy subjects, suggest the presence of a shared abnormality at the level of the presynaptic 5-HT transporter, probably linked to a common dimension yet to be identified.