Electrophysiological and Behavioral Effects of Combined Transcranial Direct Current Stimulation and Alcohol Approach Bias Retraining in Hazardous Drinkers

Background: Cognitive bias modification (CBM) can be used to retrain automatic approach tendencies for alcohol. We investigated whether changing cortical excitability with transcranial direct current stimulation (tDCS) could enhance CBM effects in hazardous drinkers. We also studied the underlying mechanisms by including behavioral (craving, implicit associations, approach tendencies) and electrophysiological (event-related potentials) measurements.

Methods: The analytical sample consisted of 78 hazardous drinkers (Alcohol Use Disorders Identification Test >8) randomly assigned to 4 conditions in a 2-by-2 factorial design (control/active CBM and sham/active tDCS). The intervention consisted of 3 sessions of CBM, specifically alcohol approach bias retraining, combined with 15 minutes 1 mA tDCS over the left dorsolateral prefrontal cortex. There was a pre- and postassessment before and after the intervention that included experimental tasks (Approach Avoidance Task, Implicit Association Task) and an electroencephalogram with an oddball and cue-reactivity task.

Results: tDCS decreased cue-induced craving (but not overall craving) on postassessment. CBM did not induce an avoidance bias during assessment. During the training, active and control-CBM only differed in bias score during the first session. We found no enhancement effects of tDCS on CBM. Electrophysiological data showed no clear effects of active tDCS or CBM on the P300.

Conclusions: There were no electrophysiological or behavioral effects of repeated CBM and/or tDCS, except for an effect of tDCS on craving. Applied in these specific ways these techniques appear to have limited effects in a hazardous drinking population.