tDCS Meta-Analysis: How Effective is it for Treating Depression?

Author Names

Lais B. Razza, Priscila Palumbo, Adriano H. Moffa, Andre F. Carvalho, Marco Solmi, Colleen K. Loo and Andre Russowsky Brunoni

Published Date: February 2020

Journal Name: Anxiety and Depression Association of America

Abstract

This systematic review and meta-analysis assess the efficacy of transcranial direct current stimulation (tDCS) in treating depressive episodes. The analysis includes 23 randomized, sham-controlled clinical trials with 1,092 participants. The results show that active tDCS significantly reduces depressive symptoms compared to sham treatment. The study also examines response and remission rates, which favour tDCS. Despite the positive findings, the overall effect size is modest, indicating that while tDCS is effective, its impact is not as strong as some other treatments.

Key Concepts

• Transcranial Direct Current Stimulation (tDCS): A non-invasive neuromodulation technique that delivers a weak electrical current to the brain, aiming to modulate neuronal activity to alleviate depressive symptoms.

• Major Depressive Disorder (MDD): A mental health condition characterized by persistent feelings of sadness and loss of interest, often accompanied by physical symptoms.

• Sham-Controlled Trials: A research method where one group receives the active treatment, and the other receives a placebo (sham) to compare the effectiveness of the treatment.

• Literature Review: Previous studies have yielded mixed results on the effectiveness of tDCS for MDD, with some trials showing significant benefits while others did not. This meta-analysis aims to provide a more comprehensive assessment by pooling data from multiple trials.

Procedure Highlights - Research Methodology

1. Study Selection: A systematic review of databases including PubMed, EMBASE, and the Cochrane Library, covering studies published until January 2020.

2. Eligibility Criteria: Included only randomized, sham-controlled trials involving participants with an acute depressive episode. The studies compared active tDCS with sham treatment and assessed depressive symptoms using standardized scales.

3. Data Extraction: Depression scores, response and remission rates, and other relevant metadata were extracted from the selected studies.

4. Analysis: The primary outcome was the effect size (Hedges’ g) for continuous depression scores. Secondary outcomes included odds ratios (ORs) for response and remission rates and the number needed to treat (NNT). A random-effects model was used to account for study heterogeneity.

Results - Findings of the Research

• Effect Size: Active tDCS was superior to sham treatment, with a pooled effect size of Hedges’ g = 0.46 (95% CI: 0.22–0.70), indicating a moderate effect in reducing depressive symptoms.

• Response Rates: The response rate for active tDCS was 33.3% compared to 16.56% for sham, with an odds ratio (OR) of 2.28 (95% CI: 1.52–3.42). The number needed to treat (NNT) to achieve one additional responder was 6.

• Remission Rates: Remission rates were also higher in the active tDCS group (19.12%) compared to sham (9.78%), with an OR of 2.12 (95% CI: 1.42–3.16) and an NNT of 10.7.

• Heterogeneity: The analysis revealed moderate to high heterogeneity across studies (I² = 70.1%), indicating variability in study outcomes.

• Publication Bias: No significant publication bias was detected, suggesting the results are robust.

Discussion and Conclusion of the Research

The meta-analysis confirms that tDCS is modestly effective in treating depressive episodes, with superior response and remission rates compared to sham treatment. However, the effect size is small to medium, indicating that while tDCS can be beneficial, its overall impact may not be as strong as other treatment modalities like pharmacotherapy.

The findings support the use of tDCS as an adjunctive treatment for depression, particularly in cases where conventional treatments are not fully effective. Further large-scale, well-designed trials are needed to explore the potential of tDCS and refine its application in clinical practice.

Link to the Original Paper

A systematic review and meta-analysis on the effects of transcranial direct current stimulation in depressive episodes

Author Information

• Lais B. Razza: Laboratory of Neurosciences, University of São Paulo, Brazil

• Priscila Palumbo: Laboratory of Neurosciences, University of São Paulo, Brazil

• Adriano H. Moffa: Black Dog Institute, School of Psychiatry, University of New South Wales, Australia

• Andre F. Carvalho: Department of Psychiatry, University of Toronto, Canada

• Marco Solmi: Department of Neurosciences, University of Padova, Italy

• Colleen K. Loo: School of Psychiatry, University of New South Wales, Australia

• Andre Russowsky Brunoni: Laboratory of Neurosciences, University of São Paulo, Brazil

Mave Health Disclaimer

The content provided here is an interpretation of a research paper for educational purposes. It is simplified to make the findings accessible to a general audience. For detailed information, please refer to the original research paper.