[A pilot study of transcranial alternating current stimulation in the treatment of drug-naive adult patients with major depressive disorder].

Objective: To explore the efficacy, adverse reactions, feasibility, and acceptability of transcranial alternating current stimulation (tACS) treating drug-naive adult patients with major depressive disorder (MDD), and provide basis for further study with a large sample. Methods: The study was performed in the Neuromodulation laboratory, Department of Neurology of Xuanwu Hospital, Capital Medical University (Beijing, China) from July, 2017 to June, 2018. Thirty Eligible first-episode MDD outpatients were randomized 1∶1 to receive active tACS or sham intervention. The tACS was administered in a 40 minute, 77.5 Hz frequency, 15 mA session with one forehead (Fp1, Fpz, and Fp2, in the 10/20 international placement system, 4.45 cm×9.53 cm) and two mastoid (3.18 cm×3.81 cm) stimulation for 20 times in 4 consecutive weeks at fixed day time frame once daily from Monday through Friday, with weekends off (week 4), followed by 4 weeks with no tACS treatment (week 8). By utilizing the Hamilton rating scale for depression-17 item (HRSD-17) to assess the depressive severity of MDD patients, adverse events were administered by the treatment-emergent adverse events, the Young mania rating scale, and the self-made common questionnaire on cranial electrical stimulation. The primary efficacy outcome was the remission rate defined as HRSD-17 score ≤7 at week 8. Secondary outcomes included the rates of remission at week 4 and response at weeks 4 and 8. Safety was assessed by evaluation of adverse events. Also the proportions of participants accepting the intervention and this study procedure were evaluated at weeks 4 and 8. Results: Thirty MDD patients completed the study, and both groups had no statistical differences on their demographic characteristics (P>0.05). At week 8, the active group had a remission rate of 10/15, which was higher than 3/15 in the sham group (P<0.05). Also, the remission rate (14/15) in the active group was higher than 5/15 of the sham group at week 4 (P<0.05). For the response rates, significant differences were found between groups at week 8. For safety, both groups showed no severe adverse events and no mania/hypomania. One participant per group had 2 times of tinnitus cerebri during the intervention days. All patients accepted the intervention and the study procedure. Conclusions: The pilot study indicated that tACS with 77.5 Hz and 15 mA may have a therapeutic effect on depressive symptoms. It is well-tolerated and safe, as well as feasible and acceptable for adults with MDD.