A double-blind sham-controlled phase 1 clinical trial of tDCS of the dorsolateral prefrontal cortex in cocaine inpatients: craving, sleepiness, and contemplation to change

Abstract

Impaired inhibitory control accompanied by enhanced salience attributed to drug-related cues, both dorsolateral prefrontal cortex (dlPFC) functions, are hallmarks of drug addiction, contributing to worse symptomatology including craving. dlPFC modulation with transcranial direct current stimulation (tDCS) showed craving reduction in inpatients with cocaine use disorder (CUD). Our study aimed at assessing feasibility of a longer tDCS protocol in CUD (15 vs. the common five/10 sessions), and replicability of previous results. In a randomized double-blind sham-controlled protocol, 17 inpatients were assigned to either a real-tDCS (right anodal/left cathodal) or a sham-tDCS condition, for 15 sessions. Primary outcome measures were self-reported craving, anxiety, depression, and quality of life. Secondary measures included sleepiness, readiness to change drug use, and affect. We also assessed cognitive function including impulsivity. An 82% retention rate demonstrated feasibility. Partially supporting previous results, there was a trend for self-reported craving to decrease in the real-tDCS group more than the sham group, an effect that would reach significance with 15 subjects per group. Quality of life and impulsivity improved over time of treatment in both groups. Significant group × time interactions showed improvements after treatment only in the real-tDCS group for daytime sleepiness and readiness to change drug use. One-month follow-up suggested transient effects of tDCS on sleepiness and craving. This study suggests that more subjects are needed to show a unique effect of real-tDCS on craving and to examine the duration of effect. Increased vigilance and motivation to change in the real-tDCS group suggest fortification of dlPFC-supported executive functions.