Striatal dopamine function during gambling in pathological gamblers: Interim analysis of ongoing [11C]raclopride PET study

Methods: The results from 6 male pathological gamblers (DSM-IV criteria) and 7 healthy male controls without gambling problems were included in this interim analysis. Each subject underwent a brain MRI scan, a psychiatric interview, laboratory tests and medical examination to exclude other conditions or medications possibly affecting to the dopaminergic neurotransmission. The groups were balanced according to age, BMI, smoking status and handedness. Each subject was scanned with [11C] raclopride PET under three counter-balanced conditions: reward, noreward and control task. During reward and no-reward scans, the subjects were instructed to gamble with a slot machine software which was projected on a screen in front of the scanner. The subjects controlled game functions with a computer mouse while laying supine in the scanner. In both reward and no-reward scans, monetary end result (real money) was pre-programmed to the software. In the reward scan, the wins increased rapidly from 20€ to 100€, whereas in no-reward task, it was impossible to win. Control task was to select A or B when lit on the screen. Head motion tracking (Polaris) was applied during the scans and motion correction was performed when appropriate. Brain MRIs were used as structural reference. Region of interest (ROI) analysis with simplified reference tissue model was used.