Effect of prefrontal tDCS on resting brain fMRI graph measures in Alcohol Use Disorders: A randomized, double-blind, sham-controlled study

Objectives: Transcranial Direct Current Stimulation (tDCS) is a promising new adjuvant approach in the treatment of Alcohol Use Disorders (AUDs) that has the potential to ameliorate the aberrations secondary to chronic alcohol use. In this study, using a randomized, double-blind, sham-controlled, parallel-arm design, we examined the effects of prefrontal tDCS on resting-state functional magnetic resonance imaging (rsfMRI) and its correlates with impulsivity and time to first lapse in subjects with AUDs.

Methods: Patients with AUD as per DSM-5 criteria were randomly allocated to receive a five-day course of either verum-tDCS (n = 12) or sham-tDCS (n = 12). Of them, 21 patients (verum/sham = 11/10) participated in both baseline and post-intervention 10-min rsfMRI sessions. Outside the scanner, subjects also performed the Stop-Signal Task at two time-points (baseline and post-intervention), which provided a measure of changes in impulsivity following tDCS. After completion of the post-intervention scan, all subjects were discharged and were followed-up for 90 days post-discharge or until lapse to first alcohol use.

Results: Graph theoretical analysis of rsfMRI data revealed that verum-tDCS (but not sham) resulted in a significant increase in the global efficiency of brain networks with a concurrent significant reduction in global clustering; network-based statistical analysis identified a significant increase in the functional connectivity of a specific sub-network involving prefrontal regions. Furthermore, increased global efficiency of brain networks following verum tDCS predicted a significantly reduced likelihood of relapse. In addition, a reduction in the global clustering had a significant positive correlation with a reduction in the measure of impulsivity.

Conclusions: The present study adds further support to the increasing evidence base for the clinical utility of tDCS in AUDs. Importantly, we observed improvement in both whole-brain network efficiency as well as inter-regional connectivity within a specific local prefrontal sub-network that is relevant to the neurobiology of AUDs. Replication and extension of these promising leads from the present study can facilitate clinical translation of tDCS, given its advantages (i.e. safety, cost-effectiveness, administration ease with potential for remotely-supervised / home-based application) for treating patients with AUDs.