Transcranial direct current stimulation (tDCS) in the treatment of depression: Systematic review and meta-analysis of efficacy and tolerability

Background: Transcranial direct current stimulation (tDCS) is a potential alternative treatment option for major depressive episodes (MDE). Objectives: We address the efficacy and safety of tDCS in MDE, Methods: The outcome measures were Hedges' g for continuous depression ratings, and categorical response and remission rates. Results: A random effects model indicated that tDCS was superior to sham tDCS (k-11, N = 393, g = 0.30, 95% Cl = [0.04, 0.57], p = 0.027). Adjunctive antidepressant medication and cognitive control training negatively impacted on the treatment effect. The pooled log odds ratios (LOR) for response and remission were positive, but statistically non-significant (response: k = 9, LOR = 0.36,95% CI[-0.16, 0.88] , p = 0.176, remission: k = 9, LOR = 0,25,95% CI [-0.42, 0.91], p = 0.468). We estimated that for a study to detect the pooled continuous effect (g = 0.30) at 80% power (alpha = 0.05), a total N of at least 346 would be required (with the total N required to detect the upper and lower bound being 49 and 12,693, respectively). Conclusions: tDCS may be efficacious for treatment of MDE. The data do not support the use of tDCS in treatment-resistant depression, or as an add-on augmentation treatment. Larger studies over longer treatment periods are needed. (C) 2015 Elsevier Ltd. All rights reserved.