The efficacy of transcranial direct current stimulation (tDCS) combined with cognitive behavioural therapy for major depressive disorder: a systematic review and meta-analysis of randomised controlled trials.
O. A. F. S. Da Silva, S. I. D. S. Pereira, A. Mert, D. R. de Aguiar, M. B. Nogueira, J. C. de Araujo, G. A. Prilip, N. N. SherpaIntroduction
Major depressive disorder (MDD) is a prevalent mental health condition, affecting around 10% of the population worldwide. Conventional treatments include psychotherapy, pharmacotherapy, and neuromodulation. Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique that has shown promise in alleviating depressive symptoms. Given evidence that tDCS enhances cognitive control and emotional regulation, it has been hypothesised that combining tDCS with cognitive behavioural therapy (CBT) may yield synergistic therapeutic benefits.
Objectives
To evaluate the efficacy of tDCS combined with CBT in reducing depressive symptoms in patients with MDD, compared with sham tDCS combined with CBT.
Methods
A systematic search of PubMed, Embase, and Cochrane Library databases was conducted in accordance with PRISMA guidelines. The primary outcome was change in depressive symptom severity from pre- to post-intervention. Secondary outcomes included remission and response rates. Data were analysed using Review Manager 5.1.7 (Cochrane Collaboration). Standardised mean differences (SMDs) and risk ratios (RRs) were calculated using random-effects models, with heterogeneity assessed via the I² statistic. Statistical significance was set at p < 0.05.
Results
Five RCTs comprising 173 patients were included; 91 (52.6%) received active tDCS plus CBT. Active tDCS plus CBT did not show a significant advantage over sham tDCS plus CBT for depressive symptom reduction (SMD = –0.14; 95% CI –0.68 to 0.39; p > 0.05; I² = 5%). Likewise, no significant differences were found for remission (RR = 1.49; 95% CI 0.61 to 3.64; p > 0.05; I² = 0%) or response rates (RR = 1.16; 95% CI 0.52 to 2.59; p > 0.05; I² = 4%). The forest plots for the outcomes of reduction in depressive symptoms and response rates can be seen, respectively, in Figures 1 and 2:
Image 1: Long description.