Cannabis use and striatal D2 receptor density in untreated first-episode psychosis: an in vivo SPECT study

The biological basis of the association between cannabis-induced dopamine dysregulation and psychosis remains poorly understood. This (123)I-IBZM SPECT study assessed striatal dopamine D2 receptor (D2R) binding in 37 untreated first-episode psychosis (FEP) subjects, and 18 healthy controls. The aim was to examine if there were differences between FEP subjects with (n=14) and without (n=23) cannabis use in uptake ratios in the D2R. Striatal/Frontal cortex (S/F) uptake ratios were obtained. Healthy controls showed the lowest D2R binding ratios. No differences were found in S/F ratios between users and non-users, suggesting similar dopaminergic mechanisms underlying psychotic symptoms in both groups.