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 3,5 × 7 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.