Abstract
BackgroundTranscranial direct current stimulation (tDCS) has shown mixed results for depression treatment. The efficacies of tDCS combination therapies have not been investigated deliberately. This review aims to evaluate the clinical efficacy of tDCS as a monotherapy and in combination with medication, psychotherapy, and ECT for treating adult patients with major depressive disorder (MDD) and identified the factors influencing treatment outcome measures (i.e. depression score, dropout, response, and remission rates).MethodsThe systematic review was performed in PubMed/Medline, EMBASE, PsycINFO, Web of Sciences, and OpenGrey. Two authors performed independent literature screening and data extraction. The primary outcomes were the standardized mean difference (SMD) for continuous depression scores after treatment and odds ratio (OR) dropout rate; secondary outcomes included ORs for response and remission rates. Random effects models with 95% confidence intervals were employed in all outcomes. The overall effect of tDCS was investigated by meta-analysis. Sources of heterogeneity were explored via subgroup analyses, meta-regression, sensitivity analyses, and assessment of publication bias.ResultsTwelve randomised, sham-controlled trials (active group: N = 251, sham group: N = 204) were included. Overall, the integrated depression score of the active group after treatment was significantly lower than that of the sham group (g = − 0.442, p = 0.017), and further analysis showed that only tDCS + medication achieved a significant lower score (g = − 0.855, p < 0.001). Moreover, this combination achieved a significantly higher response rate than sham intervention (OR = 2.7, p = 0.006), while the response rate remained unchanged for the other three therapies. Dropout and remission rates were similar in the active and sham groups for each therapy and also for the overall intervention. The meta-regression results showed that current intensity is the only predictor for the response rate. None of publication bias was identified.ConclusionThe effect size of tDCS treatment was obviously larger in depression score compared with sham stimulation. The tDCS combined selective serotonin re-uptake inhibitors is the optimized therapy that is effective on depression score and response rate. tDCS monotherapy and combined psychotherapy have no significant effects. The most important parameter for optimization in future trials is treatment strategy.
Highlights
Transcranial direct current stimulation has shown mixed results for depression treatment
There are effective pharmacological and physical treatments for major depressive disorder (MDD), about 50% of patients show an inadequate response to an individual antidepressant trial [3], about 25.5% show no response to electroconvulsive therapy [4], and 15.5–69% show insufficient response to repetitive transcranial magnetic stimulation [5]
We found that factors such as demographics [34, 35], clinical characteristics [28, 35], and montages [28, 33] have been investigated as factors influencing the efficacy of Transcranial direct current stimulation (tDCS)
Summary
Transcranial direct current stimulation (tDCS) has shown mixed results for depression treatment. The number of clinical trials investigating the efficacy of transcranial direct current stimulation (tDCS) is rapidly increasing [7] due to its non-invasive nature, few side effects [8], and low economic burden [9]. This exploratory treatment has been tested widely for the treatment of major depressive disorder (MDD) [10,11,12,13]. TDCS showed potential in patients with bipolar disorder in a major depressive episode [19,20,21] and postpartum depression [22], as well as in adult [23, 24] and elderly [25] populations
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