Serotonin transporters in obsessive-compulsive disorder: A positron emission tomography study with [¹¹C]McN 5652

Background: Serotonergic abnormalities have been hypothesized to contribute to obsessive-compulsive disorder (OCD). This study examined whether brain serotonin transporter (SERT) availability is altered in OCD using positron emission tomography (PET) and the SERT PET radiotracer [ ¹¹C]McN 5652. Methods: Eleven OCD subjects, free of psychiatric medications and comorbid depression, and 11 matched healthy control subjects underwent PET scans following injection of [¹¹C]McN 5652 and magnetic resonance imaging (MRI) scans. Total distribution volumes (V _T) were derived by kinetic analysis (one tissue compartment model) using the arterial input function. Two measures of SERT availability were computed: binding potential (BP) and specific to nonspecific partition coefficient (V₃″). Groups were compared using region of interest (ROI) analysis and voxelwise analysis of spatially normalized parametric maps; ROIs were selected based on their relatively high SERT density and included subcortical (dorsal caudate, dorsal putamen, ventral striatum, midbrain, thalamus) and limbic (hippocampus, amygdala, anterior cingulate cortex) regions. Results: No significant group differences were observed in [¹¹C]McN 5652 BP or V₃″ in the ROIs. No significant group differences were detected in the voxelwise analysis of BP or V ₃″ maps. Conclusions: OCD without comorbid depression, may not be associated with major changes in SERT availability in subcortical and limbic regions.