Violet light photobiomodulation therapy for depression: A double-blind randomized crossover trial

Medication-supplemented psychotherapy is the primary treatment for mild major depressive disorder (MDD). However, limited resources and patient non-adherence present challenges, necessitating innovative and less burdensome interventions. This study aimed to compare the effectiveness of active and placebo violet light irradiation goggles for treating mild MDD.

The present study was a randomized, double-blind, placebo-controlled trial with a crossover design conducted at the Shinjuku-Yoyogi Mental Lab Clinic between June 2021 and December 2023. A total of 57 Japanese outpatients aged 20-74 years diagnosed with mild MDD were randomly assigned to use active or placebo 40-Hz violet light irradiation goggles for 4 weeks by adaptive allocation. Each participant wore their goggles for 4 weeks with 4-week washout intervals, while their medications for depression remained unchanged. The primary endpoints were the changes in the Montgomery-Åsberg Depression Rating Scale score (Phases I and II) 4 weeks after wearing the active and placebo goggles and differences between the group's scores. The safety of the violet light irradiation goggles was also investigated.

The Montgomery-Åsberg Depression Rating Scale scores of the participants who wore active violet light irradiation goggles significantly improved compared with those of their counterparts, who wore placebo goggles (95 % confidence interval: -2.5 to -0.1; p = 0.042). No adverse events related to wearing the violet light irradiation goggles were observed.

Violet light irradiation goggles are non-invasive and may be effective for treating mild MDD. Neuromodulation of the depression network via OPN5 by violet light may contribute to the anti-depressant effects.

Japan Registry of Clinical Trials (jRCTs032210260; https://jrct.niph.go.jp/latest-detail/jRCTs032210260).