A novel wearable red-light device for photobiomodulation of the brain shows promise for poststroke rehabilitation, with favourable effects on cognitive function and neuropsychiatric symptoms, as shown in a study.
Developed by senior study author Prof Zhiqian Tong from Beijing Geriatric Hospital in China, the device consists of a helmet and an abdominal belt that emit 630-nm red light from LEDs. This wavelength was able to penetrate through a 0.8–1-cm thick skull, with an estimated penetration rate of approximately 48 percent, in an earlier assessment. [Ageing Res Rev 2024;94:102183]
The device was designed to help improve cognitive impairment and depressive-like behaviours in stroke survivors by modulating formaldehyde metabolism.
“Excessive formaldehyde exposure has been shown to cause memory decline in healthy adult mice, and formaldehyde accumulation in the brain is known to increase progressively with age, correlating with cognitive decline in humans,” Tong noted. [Age 2013;35:583-596; J Alzheimers Dis 2017;55:1031-1038; Chem Res Toxicol 2019;32:820-830; Neurosci Bull 2014;30:172-184]
In an exploratory, parallel-group, randomized controlled trial, Tong and colleagues investigated the therapeutic effects of the device on cognitive function and neuropsychiatric symptoms in 82 patients with post-stroke cognitive impairment.
These patients were randomly assigned to undergo red light irradiation with the device plus conventional treatment (n=44; mean age 61.14 years, 70.5 percent male, mean BMI 23.88 kg/m2) or conventional treatment only (n=38; mean age 64.5 years, 68.4 percent male, mean BMI 23.81 kg/m2). Red light therapy was performed five times per week, with each session lasting 30 min, for 3 months.
Patients in the control group also underwent the same number of sessions, during which the helmet and abdominal band were worn but kept switched off. Patients in both treatment groups received manual electrotherapy delivered via electrode pads during the 6-month study period.
At 6 months, patients in the red light therapy vs the control group showed greater improvements in Mini-Mental State Examination (mean difference [MD], 3.36 points, 95 percent confidence interval [CI], 1.36–5.36; p=0.002), Montreal Cognitive Assessment (MoCA) (MD, 3.48 points, 95 percent CI, 1.33–5.63; p=0.002), and Hamilton Depression Rating Scale scores (MD, −1.53, 95 percent CI, −2.86 to −0.20; p=0.027). [Front Neurol 2025;16:1634701]
Additionally, blood formaldehyde concentrations at 6 months were significantly lower in the red light therapy group than in the control group.
“Red light therapy [indeed] altered formaldehyde metabolism, as it lowered semicarbazide-sensitive amine oxidase (SSAO, an FA-generating enzyme) and hydrogen peroxide (H2O2, a marker of FA generation) levels and increased formaldehyde dehydrogenase (FDH, a formaldehyde-degrading enzyme), cytochrome c (Cyt-c), and coenzyme Q10 (CoQ10, an endogenous FA scavenger) in blood and/or urine of the patients at 6 months,” Tong explained.
Moreover, repeat strokes occurred with significantly less frequency in the red light therapy group than in the control group (2.3 percent vs 18.4 percent; p=0.037), a finding that Tong described as noteworthy.
“One potential explanation [for the reduced stroke recurrence] is that improvements in cognitive function and emotional symptoms following red light therapy may facilitate better treatment adherence, more stable lifestyle patterns, and greater engagement in secondary prevention measures,” Tong said.
Previous studies have also shown that red-light photobiomodulation can promote vasodilation, as well as reduce neuroinflammatory responses, promote neuronal survival, and support synaptic repair—effects that collectively contribute to enhanced neurovascular stability and improved resilience to recurrent ischemic events, he added. [Brain Res 2025;1868:149981; Cells 2024;13:966]
The intervention was well-tolerated, with no documented red light therapy-associated adverse events.
“The findings indicate that this novel photobiomodulation device may offer a safe and noninvasive option for poststroke cognitive and mental rehabilitation,” Tong said. “However, given the exploratory design and limited sample size, the results should be interpreted with caution and require confirmation in larger, multicentre trials.”