Transcranial direct current stimulation (tDCS) may be superior to a sham intervention when used as monotherapy or as an add-on approach in patients with major depressive disorder (MDD) or bipolar disorder (BD), according to a meta-analysis of 9 research studies published in Progress in Neuro-Psychopharmacology & Biological Psychiatry suggests. tDCS was readily accepted by patients and more effective for depression than a sham control, but the effects of the stimulation technique were moderate at best.

The researchers performed a systematic review of placebo-controlled trials of tDCS for depression in patients with MDD or BD through December 2018. The primary outcomes of interest were clinical response, remission, and depression improvement. Data from a total of 9 trials (N=572 patients; mean age, 46.8±13.3 years; 61.5% women) were analyzed. In the overall population, patients were assigned to either active tDCS (n=307) or sham intervention (n=265); 109 patients had BD and 463 patients had a type of depression.

At the time of the trial, 37.3% of patients were not receiving psychiatric drugs, whereas 36.8% and 25.2% of patients received antidepressants and benzodiazepines, respectively. Compared with sham intervention, active tDCS was superior in terms of response (30.9% vs 18.9%; odds ratio [OR], 1.96; 95% CI, 1.30-2.95; P <.01), remission (19.9% vs 11.7%; OR, 1.94; 95% CI, 1.19-3.16; P <.01), and depression improvement (β=0.31; 95% CI, 0.15-0.47; P <.01).

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For response and remission, the numbers needed to treat were 9 (95% CI, 5.2-19.7) and 13 (95% CI, 7.1-44.2), respectively. There was no significant difference between the active tDCS and sham intervention groups in the proportion of patients who did not complete the trials (14.7% vs 10.9%; OR, 1.37; 95% CI, 0.83-2.27; P =.22).

Limitations of the analysis were the small number of trials included and the lack of a trial that assessed tDCS in combination with pharmacotherapy. According to the investigators, the overall beneficial effect associated with tDCS “shown in [randomized controlled trials] to date was modest, urging the development of strategies to identify treatment responders and to increase its efficacy.”

Disclosure: multiple study authors reported conflicts of interest. Please see the original paper for full details.

Reference

Moffa AH, Martin D, Alonzo A, et al. Efficacy and acceptability of transcranial direct current stimulation (tDCS) for major depressive disorder: An individual patient data meta-analysis [published online December 16, 2019]. Prog Neuropsychopharmacol Biol Psychiatry. doi: 10.1016/j.pnpbp.2019.109836.