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Unsupervised, at-home use of transcranial direct current stimulation (tDCS) was no better than a sham control for treating a major depressive episode, a randomized trial showed.

The PSYLECT trial of 210 adults in Brazil showed no differences in mean changes in Hamilton Depression Rating Scale-17 (HDRS-17) scores over 6 weeks across three groups: a double-active group, a tDCS-only group, and a double-sham group (8.2, 8.5, and 7.7, respectively), Andre Brunoni, MD, PhD, of the University of São Paulo Medical School in Brazil, and colleagues reported in .

"It seems that tDCS might take more time than 6 weeks to develop clinically meaningful effects," Brunoni told MedPage Today in an email. "Therefore, it should not be used, particularly as monotherapy, in more severe episodes in which a faster response is necessary."

Better treatments for major depression are sorely needed, the researchers said. Unlike transcranial magnetic stimulation and electroconvulsive therapy, they said, tDCS is portable, inexpensive, and has minimal side effects. The problem is that it needs to be applied daily, which can be limited by clinical worker availability and patient ability to come into the clinic.

Thus, at-home use of tDCS could be a good alternative treatment, and at least one small study has shown promising results in depression, the researchers said. Indeed, portable tDCS devices have been developed and adopted, but no rigorously controlled trials of their efficacy have been done.

Also, studies of in-clinic tDCS have had varying results. A previous trial by Brunoni and colleagues published in the showed tDCS beat placebo for treating depression (though it couldn't show non-inferiority to the antidepressant escitalopram [Lexapro]) in a clinical setting. However, another study Brunoni was involved in, published in The Lancet, showed tDCS was no better than sham stimulation when paired with a selective serotonin reuptake inhibitor for treating major depressive disorder.

So Brunoni and colleagues conducted the , which enrolled 210 people in Brazil (86% female, mean age 38.9, 72% white) with an HDRS-17 score above 16 and access to a smartphone and internet at home. Exclusion criteria were any other psychiatric disorders besides anxiety, any neurologic or clinical disorders, and any contraindications for tDCS.

Participants were randomly assigned to one of three groups of at-home use: a double-active group involving tDCS plus digital intervention (64), a tDCS-only group (73), and a double-sham group that used sham stimulation and a digital placebo (73).

For the stimulation intervention, participants were given a device that administered 2-mA stimulation and were asked to conduct 30-minute sessions each day for 15 straight weekdays. During the final 3 weeks, participants switched to twice-weekly sessions.

For the double-active group, the added digital intervention was delivered during the stimulation and was based on behavioral therapy. The digital placebo consisted of free internet browsing using the same interface as the active intervention. Sham stimulation was 1 mA for 90 seconds.

Response rates, a secondary outcome of the study, were similar across groups (31% for double-active, 36% for tDCS-only, and 38% for double-sham), as were remission rates (14%, 18%, and 21%, respectively), the researchers found.

The results couldn't be explained by low adherence or poor usability of the at-home tDCS device, although both have been problematic in previous home-based trials, the researchers said. The home-based setting could have diminished the placebo response, but the findings were similar to previous on-site trials of tDCS as well, they noted.

Brunoni noted that the short trial duration was a key limitation of the study, as it was likely too short to produce meaningful clinical effects. Other limitations include the lack of precision on electrode positioning and the heterogeneous effects of the digital intervention modules.

He and colleagues concluded that the results suggested tDCS was ineffective for major depressive episodes, especially as a home-based intervention.

"The main indication of tDCS continues to be for mild depressive disorder, in which [it] is possible to wait several weeks for antidepressant effects," Brunoni said. He added that tDCS "could be an interesting alternative, for instance, coupled with other non-pharmaceutical interventions, such as physical activity."

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