PHOTObiomodulation for REsistant Depression Study: An Open-Label Pilot Trial on Transcranial Photobiomodulation for Treatment-Resistant Depression

Abstract

Purposes:

To evaluate the acute effects, safety, and tolerability of an open-label whole-brain transcranial photobiomodulation (tPBM) protocol in patients with treatment-resistant depression (TRD).

Methods:

This prospective, open-label, single-arm pilot trial enrolled 29 adult outpatients with TRD with moderate-to-severe depressive symptoms (Montgomery–Åsberg Depression Rating Scale [MADRS] score ≥20) in the intention-to-treat analysis. The intervention involved a standardized whole-brain tPBM protocol delivered via a light-emitting diode-based helmet (near-infrared light, 810 nm; 12.8 W), administered in 20-min sessions, three times weekly for 4 weeks (12 sessions). The primary outcome was clinical response at the end of the acute treatment phase (T1), defined as ≥50% reduction in MADRS scores. Safety and tolerability were evaluated throughout.

Results:

In total, 22 participants completed treatment (per-protocol, n = 22): MADRS scores decreased significantly from 35.5 ± 6.9 at baseline to 22.9 ± 11.2 post-treatment, reflecting a mean change of −12.5 ± 11.3 points (p < 0.001). Clinical response was achieved in nine participants (40.9%), and remission in two (9.1%). In the intention-to-treat analysis, response and remission rates were 31.0% and 6.9%, respectively. Fourteen participants (63.6%) reported ≥1 mild-to-moderate adverse event; headache was the most common (n = 11, 50.0%). No serious adverse events occurred.

Conclusion:

A 4-week, whole-brain tPBM protocol was associated with clinically meaningful reductions in the severity of depressive symptoms in patients with TRD and was well tolerated. These findings support the feasibility and potential clinical relevance of whole-brain tPBM as a noninvasive neuromodulation strategy. Larger, randomized, sham-controlled trials are warranted to confirm efficacy and optimize stimulation parameters.