RESUMEN
BACKGROUND: Transcranial direct current stimulation (tDCS) can be an effective treatment for depression, however, the duration of the stimulation session, among other parameters, needs to be optimized. METHODS: 69 mild to moderately depressed patients (age 37.6±10.5years, 19 men) were randomized into three groups - 30-, 20-minute or sham tDCS. 10 daily sessions of anodal/sham tDCS of the left DLPFC (0.5mA; electrode 3,5×7cm) combined with 50mg/day of sertraline were performed. Mood, cognition and BDNF level were assessed before and after the treatment. RESULTS: A significant difference between groups was observed in the percent change of the Hamilton Depression Rating Scale (F(2, 66)=10.1; p<0.001). Sham group (43.4%±18.1) had a smaller improvement compared to the 30-minute (63.8%±13.4; 95% CI: 11.23-29.44; p=0.00003) and 20-minute group (53.2%±15.3; 95% CI: 0.21-19.26; p=0.045). 30-minute group had significantly greater percent improvement than 20-minute group (95% CI: 1.74-19.46; p=0.02). Responders constituted 89%, 68%, and 50% and remitters - 70%, 27%, and 35% in the 30-, 20-minute and sham groups, respectively. A significant difference in the number of responders was observed between 30-minute vs. sham group (odds ratio=8; 95% CI, 2.59-24.69; p=0.001), in remission rate - between 30-minute vs. sham (odds ratio=4.40; 95% CI, 2.02-9.57; p=0.02) and vs. 20-minute (odds ratio=6.33; 95% CI, 2.85-14.10; p=0.003) groups. Two hypomania cases and one case of blood pressure elevation were detected in the 20-minute group. Among neuropsychological tests, only the change in Digit Span Backwards test showed a significant interaction between groups (TIME*GROUP; F(2, 65)=6,6, p=0.002); a greater improvement was observed in both active groups compared to sham (p<0.05). The change in BDNF level after the treatment did not show the significant difference between groups. CONCLUSIONS: tDCS of 20- or 30-minutes combined with sertraline are efficient for the treatment of mild and moderate depression; the effect of 30min stimulation exceeds the one obtained from 20min.