Effects of home-use transcranial direct current stimulation on clusters of depressive symptoms: an ancillary analysis of the PSYLECT study.

OBJECTIVE

Major depressive disorder is heterogeneous. While transcranial direct current stimulation (tDCS) is an effective treatment, its impact on symptoms remains underexplored. This ancillary study investigated the effects of home-use tDCS on depression symptom clusters.

METHODS

Data were used from the Portable Transcranial Electrical Stimulation and Internet-Based Behavioral Therapy for Major Depression Study (PSYLECT) study, in which 210 depressed patients were randomized to active (n=137) or sham tDCS (n=73) for 6 weeks. Items from the Hamilton Depression Rating Scale were grouped into symptom clusters using hierarchical clustering. Treatment effects were analyzed with mixed regressions. An alternative clustering solution was also evaluated using a larger sample.

RESULTS

Four clusters were identified: emotional, sleep, psychomotor, and psychosomatic symptoms. None showed significant group differences (sleep: p = 0.058, Cohen's d = 0.36, emotional: p = 0.976, d = -0.01, psychosomatic: p = 0.157, d = 0.27, psychomotor: p = 0.944, d = 0.01). The alternative clustering solution produced a similar sleep cluster, where tDCS led to significant reductions (p = 0.033, d = 0.41), but no differences were observed in other clusters (emotional: p = 0.707, d = 0.07, atypical: p = 0.537, d = 0.12).

CONCLUSION

The association between tDCS and sleep improvement warrants further study. tDCS may be more effective for specific symptom clusters.