tDCS for Depression: More Effective Than Placebo?

Author Names

Colleen K. Loo, Perminder Sachdev, Donel Martin, Melissa Pigot, Angelo Alonzo, Gin S. Malhi, Jim Lagopoulos and Philip Mitchell

Published Date: August 2009

Journal Name: International Journal of Neuropsychopharmacology

Abstract

This study investigates the efficacy of transcranial direct current stimulation (tDCS) in treating major depression through a double-blind, randomized, sham-controlled trial. Forty participants with major depressive disorder were randomized to receive either active tDCS targeting the left dorsolateral prefrontal cortex (DLPFC) or sham treatment. The study aimed to replicate the parameters of previous positive studies, including using 1 mA current strength for five sessions. The results showed overall improvement in depression scores after ten sessions of active tDCS, but there was no significant difference between active and sham groups during the first five sessions Concepts

Key Concepts

• Transcranial Direct Current Stimulation (tDCS): A non-invasive brain stimulation technique that uses a low-intensity electrical current to modulate neuronal activity, potentially alleviating 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 where a placebo treatment is used to evaluate the efficacy of an active treatment, ensuring that observed effects are due to the intervention itself.

Procedure Highlights - Research Methodology

1. Study Design: A double-blind, randomized, sham-controlled trial, followed by an open-label phase for those who initially received sham treatment.

2. Participants: 40 adults diagnosed with major depressive disorder, randomly assigned to either the active tDCS group or the sham treatment group.

3. tDCS Protocol: The active tDCS group received 15 sessions of 1 mA stimulation over the left dorsolateral prefrontal cortex (DLPFC) for 20 minutes per session, spread over three weeks. The sham treatment mimicked the procedure without delivering a significant electrical current.

4. Outcome Measures: Depression severity was assessed using the Montgomery–Åsberg Depression Rating Scale (MADRS), the Hamilton Depression Rating Scale (HAMD), and the Beck Depression Inventory (BDI) at baseline, after treatment, and during follow-up.

Results - Findings of the Research

• Mood Improvement: Both active and sham groups showed significant improvements in depression scores after five sessions, with no significant difference between the groups. However, after ten sessions, the active tDCS group showed further improvement, with six participants meeting the criteria for response (≥50% reduction in MADRS scores) and five achieving remission (MADRS score ≤10).

• Neuropsychological Effects: No adverse effects on neuropsychological function were observed, and participants in both groups showed improvements in specific cognitive tests, likely due to practice effects rather than the treatment itself.

• Adverse Effects: Mild side effects were reported, including skin redness, itchiness, and transient headaches, with no severe adverse outcomes.

Discussion and Conclusion of the Research

This study demonstrated that while tDCS was safe and associated with improvements in depression scores, the initial sham-controlled phase did not show a significant difference between active and sham treatments. The findings suggest that tDCS may require a longer treatment period or higher stimulation parameters to achieve more pronounced effects. The results highlight the need for further research with more intensive protocols and in more treatment-resistant populations to determine the true efficacy of tDCS in depression.

Link to the Original Paper

A double-blind, sham-controlled trial of transcranial direct current stimulation for the treatment of depression

Author Information

• Colleen K. Loo: School of Psychiatry, University of New South Wales, Sydney, Australia; St George Hospital, South Eastern Sydney Illawarra Health Service, Australia

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

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

• Melissa Pigot: 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

• Gin S. Malhi: Discipline of Psychological Medicine, University of Sydney, Sydney, Australia

• Jim Lagopoulos: Discipline of Psychological Medicine, University of Sydney, Sydney, Australia

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

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