Positron Emission Tomography Imaging of the Serotonin Transporter and 5-HT1A Receptor in Alcohol Dependence

Background Rodent models as well as studies in humans have suggested alterations in serotonin (5-HT) innervation and transmission in early-onset genetically determined or type II alcoholism. This study examines two indices of serotonergic transmission, 5-HT transporter levels and 5-HT 1A availability, in vivo, in type II alcoholism. This is the first report of combined tracers for pre- and postsynaptic serotonergic transmission in the same alcoholic subjects and the first study of 5-HT 1A receptors in alcoholism. Methods Fourteen alcohol-dependent subjects were scanned (11 with both tracers, 1 with [ 11 C]DASB only, and two with [ 11 C]WAY100635 only). Twelve healthy control subjects (HC) subjects were scanned with [ 11 C]DASB, and another 13 were scanned with [ 11 C]WAY100635. Binding potential (BP p , mL/cm 3 ) and the specific to nonspecific partition coefficient (BP ND , unitless) were derived for both tracers using a two-tissue compartment model and compared with control subjects across different brain regions. Relationships to severity of alcoholism were assessed. Results No significant differences were observed in regional BP p or BP ND between patients and control subjects in any of the regions examined. No significant relationships were observed between regional 5-HT transporter availability, 5-HT 1A availability, and disease severity, with the exception of a significant negative correlation between 5-HT transporters and years of dependence in amygdala and insula. Conclusion This study did not find alterations in measures of 5-HT 1A or 5-HT transporter levels in patients with type II alcoholism.