Abstract
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.
Highlights
Depressive disorders are characterized by a sad, irritable and empty mood, accompanied by cognitive and somatic changes that affect social, professional and other important individual aspects
We considered studies which: 1) included in the sample individuals diagnosed with bipolar depression; 2) considered major depression (MD) as a secondary disease; 3) included only partial results or contained only the abstract; 4) used other neurostimulation technique rather than transcranial direct current stimulation (TDCS); 5) investigated other therapies in addition to pharmacotherapy, psychotherapy and cognitive control therapy; 6) investigated the use of TDCS not combined and / or compared to the therapies listed in criterion 5; 7) analyzed the results after a single treatment session; 8) investigated non-clinical or neuropsychological outcomes
Khayyer and colleagues (2018) initially reported, for one of the groups, increased clinical improvement, as well as indicators of optimism and hope, in response to psychotherapy combined with TDCS, this study presents a critical selection bias, since its sample consisted only of women with a low number (3) of patients in each group, in addition to the lack of control group and the absence of statistical tests that could attest the significance of results
Summary
Depressive disorders are characterized by a sad, irritable and empty mood, accompanied by cognitive and somatic changes that affect social, professional and other important individual aspects. Many patients with severe MD (i.e. with psychotic depression and under emergencies) may experience refractoriness to conventional drug treatment, being electroconvulsive therapy an alternative to be considered It exhibits good effectiveness, is fast and safe, it is associated with high rates of relapse (Çakir & Çağlar, 2017; Hermida et al, 2018; Swedish Council on Health Technology Assessment, 2004). Transcranial direct current stimulation (TDCS) is a non-invasive neuromodulation modality whose main effect is a change in the resting potential of the neuronal membrane, which can become more excitable (anodic stimulation) or less excitable (cathodic stimulation) (Lefaucheur et al, 2017) It employs two electrodes, the anode (positive) and the cathode (negative), arranged on the scalp above different brain regions varying according to treatment protocols. Considering the evidence that TDCS is effective for MD management, and the perspective of including this therapeutic modality among conventional treatments due to the few adverse effects and low cost (Berlim et al, 2009; Lee et al, 2017), our main objective was to evaluate the reported effectiveness of TDCS, combined or not with antidepressants, psychotherapy or cognitive therapies, on clinical and neuropsychological outcomes in MD patients, in order to answer the following question: “Is TDCS more effective alone or in combination with antidepressants, psychotherapy or cognitive therapies for the treatment of MD patients?”
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