This study investigates the similarities and differences in underlying neurobehavioral mechanisms of compulsive behaviour in pathological gambling and alcohol dependence. Twenty patients with problematic gambling behaviour and 21 alcohol dependent patients (ADs) were recruited from Dutch addiction treatment centres. Nineteen healthy controls (HCs) were recruited through advertisements in regional newspapers.
Cognitive flexibility and its neural substrates were tested with a functional Magnetic Resonance Imaging paradigm (fMRI): subjects had to respond either according to a fixed rule (repeat trials) or according to an alternative rule following an explicit cue (switch trials) without receiving any feedback. Percentage of correct responses and reaction times (RTs) were the behavioural dependent variables.
During switch trials, problematic gamblers (PRGs) showed more activity in the left parahippocampal gyrus than HCs. Furthermore, PRGs and HCs showed greater activity than ADs in the right anterior cingulate cortex (ACC). Behavioural performance was generally very similar for all groups. However, during repeat trials, PRGs and ADs responded slower than HCs and ADs activated the left inferior frontal gyrus and right motor regions more compared to HCs, whereas no brain activity differences were present between ADs and PRGs.
Our findings of subtle behavioural and functional brain activity abnormalities in PRGs and ADs during cognitive switching are different from previous studies using switching paradigms in which (monetary) feedback is provided and addictive groups show clear impairments.