Modulation of risk-taking in marijuana users by transcranial direct current stimulation (tDCS) of the dorsolateral prefrontal cortex (DLPFC)

Cognitive deficits that are reported in heavy marijuana users (attention memory affect perception decision-making) appear to be completely reversible after a prolonged abstinence period of about 28 days However it remains unclear whether the reversibility of these cognitive deficits indicates that (1) chronic marijuana use is not associated with long-lasting changes in cortical networks or (2) that such changes occur but the brain adapts to and compensates for the drug-induced changes Therefore we examined whether chronic marijuana smokers would demonstrate a differential pattern of response in comparison to healthy volunteers on a decision-making paradigm (Risk Task) while undergoing sham or active transcranial direct current stimulation (tDCS) of the dorsolateral prefrontal cortex (DLPFC) Twenty-five chronic marijuana users who were abstinent for at least 24 h were randomly assigned to receive left anodal/right cathodal tDCS of DLPFC (n = 8) right anodal/left cathodal tDCS of DLPFC (n = 9) or sham stimulation (n = 8) results on Risk Task during sham/active tDCS were compared to healthy volunteers from a previously published dataset Chronic marijuana users demonstrated more conservative (i e less risky) decision-making during sham stimulation While right anodal stimulation of the DLPFC enhanced conservative decision-making in healthy volunteers both right anodal and left anodal DLPFC stimulation increased the propensity for risk-taking in marijuana users These findings reveal alterations in the decision-making neural networks among chronic marijuana users Finally we also assessed the effects of tDCS on marijuana craving and observed that right anodal/left cathodal tDCS of DLPFC is significantly associated with a diminished craving for marijuana (C) 2010 Elsevier Ireland Ltd All rights reserved