Transcranial direct current stimulation for acute major depressive episodes: meta-analysis of individual patient data

Abstract

Background: Transcranial direct current stimulation (tDCS) is a non-pharmacological intervention for depression. It has mixed results, possibly caused by study heterogeneity.

Aims: To assess tDCS efficacy and to explore individual response predictors.

Method: Systematic review and individual patient data meta-analysis.

Results: Data were gathered from six randomised sham-controlled trials, enrolling 289 patients. Active tDCS was significantly superior to sham for response (34% v. 19% respectively, odds ratio (OR) = 2.44, 95% CI 1.38-4.32, number needed to treat (NNT) = 7), remission (23.1% v. 12.7% respectively, OR = 2.38, 95% CI 1.22-4.64, NNT = 9) and depression improvement (B coefficient 0.35, 95% CI 0.12-0.57). Mixed-effects models showed that, after adjustment for other predictors and confounders, treatment-resistant depression and higher tDCS 'doses' were, respectively, negatively and positively associated with tDCS efficacy.

Conclusions: The effect size of tDCS treatment was comparable with those reported for repetitive transcranial magnetic stimulation and antidepressant drug treatment in primary care. The most important parameters for optimisation in future trials are depression refractoriness and tDCS dose.

Conflict of interest statement

Declaration of interest

Z.J.D. has served on the advisory board for Sunovion, Hoffmann-La Roche Limited and Merck, and received speaker support from Eli Lilly.

© The Royal College of Psychiatrists 2016.

Figures

Fig. 1

Individual patient data meta-analysis comparing active v. sham transcranial direct current stimulation (tDCS) in terms of (a) response; (b) remission and (c) depression improvement. Forest plot graphically illustrating the comparative efficacy of active with sham tDCS. For each study the relative strength of treatment effects is represented, the square represents the relative weight of each study, the vertical bar is the 95% confidence interval. The rhombus represents the overall effect. Values >1 and >0 v.