Efficacy of tDCS in Depression: Insights from a 3-Week Randomized Controlled Trial

Author Names

Colleen K. Loo, Angelo Alonzo, Donel Martin, Philip B. Mitchell, Veronica Galvez and Perminder Sachdev

Published Date: February 2012

Journal Name: The British Journal of Psychiatry

Abstract

This study investigates the antidepressant efficacy and safety of transcranial direct current stimulation (tDCS) in a randomized, double-blind, sham-controlled trial. Sixty-four participants with current major depressive episodes were administered either active tDCS or a sham treatment over 15 sessions across three weeks. The results showed a significant improvement in mood after active tDCS compared to sham treatment, although responder rates were similar in both groups. Neuropsychological functioning improved, and no decline was observed after active stimulation, confirming the treatment’s safety. However, vigilance for mood switching in bipolar patients is advised.

Key Concepts

• Transcranial Direct Current Stimulation (tDCS): A non-invasive brain stimulation technique that uses a low-intensity electrical current to modulate neuronal activity and potentially alleviate depressive symptoms.

• Major Depressive Disorder (MDD): A mental health condition characterized by persistent sadness, loss of interest, and impaired daily functioning.

• Sham-Controlled Trials: Research design in which a placebo treatment is used to evaluate the efficacy of an active treatment, ensuring that the effects are due to the intervention itself.

• Literature Review: Previous studies on tDCS have demonstrated its potential in treating depression, with varying levels of effectiveness. This study builds on earlier research by using a higher current intensity and more frequent sessions to optimize outcomes.

Procedure Highlights - Research Methodology

1. Study Design: A double-blind, randomized, sham-controlled trial with an additional 3-week open-label phase.

2. Participants: 64 adults diagnosed with a major depressive episode according to DSM-IV criteria. Participants were randomly assigned to receive either active tDCS or sham treatment.

3. tDCS Protocol: The active tDCS group received 15 sessions of 2 mA stimulation over the left dorsolateral prefrontal cortex (DLPFC) for 20 minutes each, across three weeks. Sham treatment mimicked the procedure without delivering a significant electrical current.

4. Outcome Measures: Mood was assessed using the Montgomery–Åsberg Depression Rating Scale (MADRS) at multiple time points: baseline, post-session 15, and follow-up. Neuropsychological functioning was also evaluated.

Results - Findings of the Research

• Mood Improvement: The active tDCS group exhibited a significantly greater improvement in mood compared to the sham group, as measured by the MADRS. However, only 13% of participants in each group met the criteria for response (a 50% reduction in MADRS score).

• Neuropsychological Effects: Participants showed improvement in attention and working memory after a single session of active tDCS. No cognitive decline was observed after 3–6 weeks of active stimulation, suggesting the safety of the procedure.

• Responder Rates: Despite the mood improvements, responder rates (those showing significant clinical improvement) were similar in both the active and sham groups at 13%.

• Adverse Effects: One participant with bipolar disorder became hypomanic after active tDCS, indicating a need for caution when administering tDCS to individuals with bipolar disorder. Other side effects were mild and transient.

Discussion and Conclusion of the Research

The study confirms the antidepressant efficacy and safety of tDCS, particularly in patients with major depressive disorder. While the overall mood improvement was significant, the lack of difference in responder rates between active and sham groups highlights the need for further investigation. The findings support the potential of tDCS as a treatment option for depression, though caution is advised in bipolar patients to prevent mood switching. The results also suggest that extending the treatment duration may enhance its efficacy.

Link to the Original Paper

Transcranial direct current stimulation for depression: 3-week randomized, sham-controlled trial

Author Information

• Colleen K. Loo: School of Psychiatry, University of New South Wales, Sydney, Australia; Black Dog Institute, Sydney, Australia

• Angelo Alonzo: School of Psychiatry, University of New South Wales, Sydney, Australia; Black Dog Institute, Sydney, Australia

• Donel Martin: School of Psychiatry, University of New South Wales, Sydney, Australia; Black Dog Institute, Sydney, Australia

• Philip B. Mitchell: School of Psychiatry, University of New South Wales, Sydney, Australia; Black Dog Institute, Sydney, Australia

• Veronica Galvez: School of Psychiatry, University of New South Wales, Sydney, Australia; Black Dog Institute, Sydney, Australia

• Perminder Sachdev: School of Psychiatry, University of New South Wales, Sydney, Australia; Neuropsychiatric Institute, Prince of Wales Hospital, Sydney, Australia

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