Transcranial direct current stimulation (tDCS) for depression

A systematic review and meta‑analysis of 7 randomised controlled trials (RCTs) including 259 patients treated by active transcranial direct current stimulation (tDCS; n=137) or sham tDCS (n=122) reported a significantly greater improvement in depressive symptoms in the active tDCS group using Hedges' g as the measure of the effect size, which standardises studies using different depression scales (Hedges' g=0.37; 95% confidence interval [CI] 0.04 to 0.7) compared against the sham tDCS group. An RCT of 120 patients treated by active tDCS plus sertraline (n=30), active tDCS plus placebo (n=30), sham tDCS plus sertraline (n=30), or sham tDCS plus placebo (n=30) reported significantly lower Montgomery–Åsberg Depression Rating Scale (MADRS) scores (10 items measured on a scale of 0 to 6 with low values indicating less depression) after 6 weeks in patients treated by active tDCS plus sertraline compared against patients treated by sham tDCS plus sertraline (mean difference 8.5 points; 95% CI 2.96 to 14.03; p=0.002). Significantly lower MADRS scores after 6 weeks were also reported in patients treated by active tDCS plus placebo compared against patients treated by sham tDCS plus placebo (mean difference 5.6 points; 95% CI 1.30 to 10.01; p=0.01).

The systematic review of 7 RCTs including 259 patients reported significantly better treatment response rates (defined as an improvement greater than 50% in depression scores from baseline to end point) in the active tDCS group compared against the sham tDCS group (odds ratio [OR] 1.63, 95% CI 1.26 to 2.12).

The systematic review of 7 RCTs including 259 patients reported significantly better remission rates in the active tDCS group compared against the sham tDCS group, with scores lower than 8 in the Hamilton Depression Rating Scale (several variables assessed and measured on 5‑point or 3‑point scales, with low values indicating less depression), or lower or equal to 10 in the MADRS (OR 2.5, 95% CI 1.26 to 4.99). In the RCT of 120 patients, remission rates (according to MADRS scores) after 6 weeks were 47% (14/30) for patients treated by active tDCS plus sertraline, 40% (12/30) for patients treated by active tDCS plus placebo, 30% (9/30) for patients treated by sham tDCS plus sertraline and 13% (4/30) for patients treated by sham tDCS plus placebo (p=0.03 between groups).

A follow‑up study of 42 patients whose depression had responded ('responders') to tDCS treatment in the RCT of 120 patients reported a sustained response rate at 24 weeks in these 'responders' of 47% (95% CI, 27 to 64, measured by Kaplan–Meier survival analysis). Patients with treatment‑resistant depression had a much lower 24‑week sustained response rate than patients with non‑refractory depression (10% versus 77%, OR 5.52; p<0.01). The same study reported a mean response duration (for 'responders', n=42) of 11.7 weeks.

The systematic review of 7 RCTs including 259 patients reported dropout rates of 8% (12/137) in the active tDCS group and 11% (15/122) in the sham tDCS group, with no difference in treatment acceptability (OR 0.73, 95% CI 0.32 to 1.69).

The specialist advisers listed key efficacy outcomes as improvement in depressive symptoms, remission, reduction in anxiety, effectiveness in treatment resistance and improvement in other parameters including cognitive function, pain and neurological symptoms.