Remotely Supervised Home-Based tDCS in Treatment-Resistant Depression: Feasibility, Effectiveness and EEG Biomarkers of Response.

BACKGROUND: Remotely supervised home-based transcranial direct current stimulation (HB-tDCS) may expand access to neuromodulation for treatment-resistant depression (TRD), but real-world evidence on candidate biomarkers remains limited. METHODS: In this single-arm pre-post study, 40 adults with major depressive disorder and inadequate response to ≥2 treatments were enrolled. After MRI/clinical screening, 2 were excluded for potential stimulation contraindications and 5 did not start or discontinued within the first sessions for personal reasons unrelated to stimulation. 33 participants completed a 6-week semi-supervised HB-tDCS protocol (42 sessions, 30min, 2mA; anode F3/cathode F4). Baseline and post-treatment assessments included clinician-rated and self-rated depression (MADRS, QIDS-SR16, BDI-II), global cognition (MoCA), quality of life (Q-LES-Q-SF), and neurophysiological markers (resting-state EEG and TMS-EEG). Feasibility, technical incidents, and adverse effects were recorded after each session. Feasibility and safety constituted the primary outcomes; clinical and neurophysiological outcomes were treated as secondary and exploratory endpoints respectively, with biomarker analyses uncorrected for multiple comparisons. RESULTS: Completers delivered 1,219/1,386 scheduled sessions (88%). Depressive symptoms decreased from baseline to post-treatment (MADRS -24%, QIDS-SR16 -15%, BDI-II -12%; all p≤.002). Sixteen of 33 (48.5%) achieved ≥25% MADRS reduction (partial response), including 5 (15.2%) with ≥50% reduction. MoCA improved modestly, whereas Q-LES-Q-SF did not change significantly. Adverse effects were mostly mild/moderate (e.g., tingling, headache, scalp dryness), and no stimulation-related serious adverse events occurred. Exploratory analyses suggested higher baseline left-frontal alpha (F3) relative power and candidate TMS-EEG evoked potentials in the left DLPFC (P30, P180) may differentiate responders from non-responders. CONCLUSIONS: An intensive, semi-supervised HB-tDCS program was feasible and well tolerated in TRD and was associated with significant symptom reductions. Candidate EEG/TMS-EEG markers warrant replication in controlled trials.