Major depressive disorder is a severe, refractory mental disorder. Only one third of patients treated with antidepressants achieve remission after 3 trials, while subject to adverse effects. Therefore, the investigation of alternative treatments is paramount. The aim of this systematic review was to summarize the most recent evidence of transcranial direct current stimulation (tDCS) intervention for the acute phase of major depressive disorder. A PubMed search was performed including the terms “transcranial direct current stimulation” OR “transcranial direct stimulation” OR “tDCS” AND “major depressive disorder” OR “major depression” OR “depression” AND “trial.” The search was conducted from inception until February 2018. Our search yielded initially 165 results, and 14 randomized clinical trials were included according to eligibility criteria. Most studies were pilot studies, with mixed findings. Two large randomized clinical trials recently published also presented primary negative findings. Study protocols usually used anodal left/cathodal right dorsolateral prefrontal cortex stimulation, 1 to 2.5 mA, and 5 to 20 tDCS sessions. We discuss the limitations of the included trials, such as sample and tDCS parameters heterogeneity between studies. To conclude, tDCS seems to be safe and devoid of serious adverse effects, although robust efficacy has not been consistently demonstrated in clinical trials assessing an acute treatment course of up to 4 weeks. Further directions are discussed, such as parameter individualization, investigation of biological markers, and home-use tDCS.
From the *Service of Interdisciplinary Neuromodulation, Laboratory of Neurosciences (LIM-27) and National Institute of Biomarkers in Psychiatry (INBioN), Department and Institute of Psychiatry, Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de São Paulo, São Paulo, São Paulo, Brazil;
†School of Psychiatry, University of New South Wales, Black Dog Institute, Sydney, Australia; and
‡Department of Psychiatry and Psychotherapy, Ludwig Maximilian University of Munich, Munich, Germany.
Received for publication January 23, 2018; accepted April 25, 2018.
Reprints: Lucas Borrione, MD, MSc, Service of Interdisciplinary Neuromodulation, R. Dr. Ovidio Pires de Campos 785, 2o andar Ala Sul, Instituto de Psiquiatria, São Paulo, São Paulo CEP 05403-000, Brazil (e-mail: firstname.lastname@example.org).
L.B. reports personal fees from Libbs Laboratory, Apsen Laboratory, and Ache Laboratory. A.R.B. is recipient of a CAPES/Alexander von Humboldt fellowship award for experienced researchers and a consultant to the Neurocare group GmbH (Munich, Germany). D.M. is the recipient of a NARSAD Young Investigator Award from the Brain and Behavior Foundation. A.H.M. is the recipient of a Scientia PhD Scholarship from the University of New South Wales, Sydney, Australia. The other authors have no conflicts of interest or financial disclosures to report.