Results
No significant differences in clinical or demographic characteristics were observed between the active-HD, active-conventional and sham treatment groups (Supplementary material S1). No significant differences in the mean HAMD scores between treatment groups were observed (mean HAMD scores: active-HD: 17.3, active-conventional: 14.7, sham: 15.0). No significant differences in guesses of active/sham stimulation were observed between the treatment groups for participants or assessors (Participants: Significant (Gray matter changes induced by active tDCS treatment. Gray matter changes (post-treatment–baseline) for the active-HD, active-conventional and sham treatment groups were modeled voxelwise using a 1-way ANOVA with total intracranial volume, age and gender as covariates in SPM12No significant (FWEFigure Gray matter changes within individual treatment groups. A follow-up analysis was performed to investigate longitudinal gray matter changes within each individual treatment group. This provides a methodological check, since no significant changes in gray matter are expected to result from sham tDCS treatment. Additionally, significant regions identified in the active tDCS groups, though not dissociable from placebo effects in this analysis, can be used for defining a priori brain regions for future datasets investigating tDCS induced structural changes. No significant (family-wise error corrected (FWE) 