Reward-system effect (BAS rating), left hemispheric "unbalance" (alpha band oscillations) and decisional impairments in drug addiction.

The current research explored the impact of cortical frontal asymmetry (left-lateralization effect) and Behavioral Activation System (BAS) on Substance Use Disorder (SUD) in decisional processes using the Iowa Gambling Task (IGT). Forty SUD participants and forty-two controls (CG) were tested using the IGT. Behavioral responses (gain/loss options), BIS/BAS scores and lateralized alpha band modulation (LTA) were considered. The SUD group increased the tendency to opt in favor of the immediate reward (loss strategy) more than the long-term option (win strategy) compared to the CG. Secondly, higher reward-subscale scores were observed in SUD. Thirdly, SUD showed an increase in left-hemisphere activation in response to losing (with immediate reward) choices in comparison with the CG. An imbalanced left hemispheric effect related to higher BAS trait could explain this "reward bias," because these components were found to explain (through the regression analysis) the main behavioral deficits.