Serotonin 1B receptor imaging in pathological gambling

Objectives. Although serotonergic mechanisms have been implicated in pathological gambling (PG), no ligand-based imaging studies have assessed serotonin receptors in individuals with PG. Given its role in substance addictions and its abundance in brain regions implicated in PG, we evaluated serotonin 1B receptors (5-HT 1B Rs) in PG. Methods. Ten medication-free subjects with PG (meanSD age � 36.3 � 9.4 years, nine men) and ten control comparison (CC) subjects (meanSD age � 35.8 � 9.9 years, nine men) underwent ( 11 C)P943 positron emission scanning on a high resolution research tomograph. Results. 5-HT 1B R BP ND values were similar in PG and CC subjects ( P � 0.1). Among PG subjects, scores on the South Oaks Gambling Screen (SOGS) correlated positively with 5-HT 1B R BP ND values in the ventral striatum ( r � 0.66; P � 0.04), putamen ( r � 0.67; P � 0.03) and anterior cingulate cortex ( r � 0.73; P � 0.02). Conclusions. These fi ndings provide the fi rst evidence that PG severity in humans is linked to increased levels of 5-HT 1B Rs in regions previously implicated in functional neuroimaging studies of PG. These fi ndings indicate a potential role for serotonergic function in the ventral striatum and anterior cingulate cortex contributing to problem gambling severity and warrant further studies to investigate whether numbers of available 5-HT 1B Rs might represent a vulnerability factor for PG or develop in relationship to problem gambling.