Prefrontal transcranial direct current stimulation in alcohol use disorder: a pilot randomized sham-controlled trial with exploratory effects on reward craving and depressive symptoms.

Alcohol Use Disorder (AUD) is a frequent and often treatment-resistant condition, with high relapse rates and frequent psychiatric comorbidities. In this randomized, double-blind pilot trial, 38 patients with AUD were assigned to receive either active anodal transcranial direct current stimulation (tDCS) over the dorsolateral prefrontal cortex or sham stimulation, in addition to standard care. The protocol consisted of 1 mA for 20 min per session, followed by maintenance stimulation over a 12-week period. The preregistered confirmatory outcomes were changes in craving severity assessed by the Brief Substance Craving Scale (BSCS) and a visual analog scale (VAS). Active tDCS did not demonstrate superiority over sham stimulation on these registered craving outcomes. However, exploratory analyses suggested possible differential effects of active tDCS on specific clinical dimensions, including reward-related craving and depressive symptoms. In particular, active stimulation was associated with greater improvement in reward craving and depressive symptomatology at selected follow-up timepoints compared with sham stimulation. These findings should be interpreted as preliminary and hypothesis-generating, given the pilot design, limited sample size, and exploratory nature of these outcomes. No major adverse effects were observed, and treatment was generally well tolerated. Overall, this pilot trial suggests that prefrontal tDCS may warrant further investigation as a potential adjunctive intervention targeting reward-related craving and mood symptoms in AUD.