Role of hippocampal subfield volumes in the efficacy of transcranial direct current stimulation for late-life depression: An exploratory pilot randomized clinical trial.

BACKGROUND

This exploratory pilot double-blind, placebo-controlled trial evaluated the effectiveness and safety of combining transcranial direct current stimulation (tDCS) with antidepressants for late-life depression (LLD), and examined whether baseline hippocampal subfield volumes moderated treatment response.

METHODS

Thirty-three elderly patients with LLD receiving antidepressant treatment were enrolled in this pilot RCT and randomly assigned to active-tDCS (n = 18) or sham stimulation (n = 15). Of these, 23 completed the intervention and baseline MRI scans (active-tDCS, n = 13; sham, n = 10). Participants underwent 12 tDCS sessions over 4 weeks, with psychiatric symptoms assessed at baseline, weeks 2, 4, and 6. Baseline hippocampal volumes were measured using FreeSurfer 7.1.1.

RESULTS

Active-tDCS participants showed significant reductions in depression and anxiety scores at weeks 4 and 6, while the sham group exhibited no significant changes. No differences in hippocampal volumes were observed between active-tDCS and sham groups. Within the active-tDCS group, hippocampal subfield volumes did not differ between responders (clinical response is defined as a >50 % reduction in total HAMD scores from baseline) and non-responders. However, reductions in depressive severity were positively associated with volumes of the right presubiculum head, right presubiculum body, right subiculum head, right subiculum body, right GC-ML-DG body, right fimbria, right hippocampal tail, and right whole hippocampal body.

CONCLUSION

tDCS appears to be an effective adjunctive intervention for reducing depression in elderly LLD patients. Baseline hippocampal volume may serve as a predictive marker for tDCS outcomes. Larger-scale studies are warranted to confirm these findings.