Effectiveness of transcranial direct current stimulation alone or associated with antidepressants, psychotherapy or cognitive therapies for the management of major depression – a review on clinical trials

Considering the evidence that transcranial direct current stimulation (TDCS) is effective for major depression (MD) management, and the perspective of including this therapeutic modality among conventional treatments, our main objective was to evaluate the reported effectiveness of TDCS, combined with antidepressants, psychotherapy or cognitive therapies, on clinical and neuropsychological outcomes in MD patients. We performed an integrative review of clinical trials, guided by the PICO strategy, using PubMed and Ovid MEDLINE ® databases. Twelve scientific reports were selected according to inclusion and exclusion criteria, comparatively analyzed, discussed and theorized. According to these studies, anodic TDCS applied to the left dorsolateral prefrontal cortex exhibits significant antidepressant effects, comparable to low dose sertraline (50 mg/day). In addition, two main studies indicate that antidepressant effects can be enhanced by combined treatments, especially TDCS + sertraline. There is also evidence of a synergistic effect of TDCS and cognitive control training, although this finding is not unanimous under different methodological approaches, thus requiring further studies in order to support the correlation between neurocognitive and clinical improvement with this type of combined therapy. Finally, TCDS-induced positive cognitive effects, mainly on working memory, were also verified. In conclusion, the small number of reports employing TDCS associated with other therapies show very discrepant research methods, as well as short follow-up periods, which together with low sample number, leave many knowledge gaps to be answered by future studies.