Protocol on transcranial alternating current stimulation for the treatment of major depressive disorder: a randomized controlled trial

Background: Transcranial alternating current stimulation (tACS) offers a new approach for adult patients with major depressive disorder (MDD). The study is to evaluate the efficacy and safety of tACS treating MDD. Methods: This is an 8-week, double-blind, randomized, placebo-controlled study. Ninety-two drug-naive patients with MDD aged 18 to 65 years will receive 20 daily 40-min, 77.5-Hz, 15-mA sessions of active or sham tACS targeting the forehead and both mastoid areas on weekdays for 4 consecutive weeks (week 4), following a 4-week observation period (week 8). The primary outcome is the remission rate defined as the 17-item Hamilton depression rating scale (HDRS-17) score <= 7 at week 8. Secondary outcomes are the rates of response at weeks 4 and 8 and rate of remission at week 4 based on HDRS-17, the proportion of participants having improvement in the clinical global impression-improvement, the change in HDRS-17 score (range, 0-52, with higher scores indicating more depression) over the study, and variations of brain imaging and neurocognition from baseline to week 4. Safety will be assessed by vital signs at weeks 4 and 8, and adverse events will be collected during the entire study. Discussion: The tACS applied in this trial may have treatment effects on MDD with minimal side effects.