Transcranial direct current stimulation of 20-and 30-minutes combined with sertraline for the treatment of depression

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 +/- 10.5 years, 19 men) were randomized into three groups -30-, 20-minute or sham tDCS. 10 daily sessions of anodal/sham tDCS of the left DLPFC (0.5 mA; electrode 3,5x7 cm) combined with 50 mg/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 30 min stimulation exceeds the one obtained from 20 min.