Explore how red and near-infrared light therapy may support recovery in patients with traumatic brain injury (TBI) by enhancing brain function and reducing inflammation.
According to a pilot study by researchers at the Wellman Center for Photomedicine, Massachusetts General Hospital (MGH), light therapy appears safe and produces measurable brain effects.
Senior investigators Rajiv Gupta, MD, PhD, director of the Ultra-High Resolution Volume CT Lab at MGH, and Benjamin Vakoc, PhD, at the Wellman Center, led the randomized trial, funded by the Department of Defense and published in JAMA Network Open on 14 September.
The study is among the first prospective, randomized, interventional trials of near-infrared, low-level light therapy (LLLT) in patients with recent moderate traumatic brain injury (TBI). If larger trials confirm the findings, LLLT might offer a widely accepted early treatment option.
TBI is the leading cause of trauma-related disability worldwide; an estimated 69 million cases occur annually. No established therapies exist, partly because acute-stage research is difficult and the underlying biology remains unclear.
“The Gulf War highlighted TBI: body armor had improved, yet shock waves from high-powered explosives still injured the brain.”
Rajiv Gupta, MD, PhD, Director, Ultra-High Resolution Volume CT Lab
Global TBI incidence has since risen, and effective treatments are still needed. The team therefore engineered a helmet to deliver near-infrared light, combining expertise in medicine, physics, and engineering.
Participants included neuroradiologist Gupta, applied physicist Vakoc, and specialists in optical instrumentation; both Gupta and Vakoc are associate professors at Harvard Medical School.
“We translated Wellman Center research into a practical near-infrared protocol, working with the DOD to address TBI,” said Rox Anderson, MD, the center’s director.
Another hurdle was selecting the optimal wavelength.
“No one knew the ideal dose,”
said co-author Lynn Drake, MD, director of business development at the Wellman Center.
“We refined wavelength, dose, timing, and exposure through pre-clinical experiments.”
Those studies, led by Anderson and Michael Hamblin, PhD, suggested mitochondria-mediated neuroprotection. After several years of bench work, the team launched the clinical trial.
Sixty-eight patients with moderate TBI were randomized: one group received LLLT via the helmet; the control group wore the inactive helmet for the same duration.
Vakoc’s team at Wellman designed the helmet. During the study, the subjects’ brains were tested for neuron activity using quantitative magnetic resonance imaging (MRI) metrics, and the subjects also underwent neurocognitive function assessment.
MRI was performed in the acute (within 72 hours of injury), early subacute (2–3 weeks), and late subacute (about three months) stages of recovery. At each visit and at six months, clinical assessments were performed with the Rivermead Post-Concussion Questionnaire, with each item rated on a five-point scale.
Twenty-eight patients completed at least one LLLT session, and none reported adverse reactions. The researchers also found measurable effects of transcranial LLLT on the brain.
MRI showed statistically significant differences in myelin integrity around neurons in treated patients compared with controls. These findings support larger follow-up trials, especially because no other treatments exist for these patients.
The study also showed that light can influence cells. Although it is well established that cells have light receptors, “going into this trial we had several unanswered questions, such as whether the light would pass through the scalp and skull, whether the dose was sufficient, and whether it would engage the neural substrates responsible for repair after TBI,” says Gupta.
He notes that this initial study focused on patients with moderate traumatic brain injury, which helped ensure statistically significant findings because this group is more likely to show a measurable effect.
“It would be much more difficult to see such changes in patients with mild injuries, and in patients with severe brain injuries the effect of light therapy might be confounded by other comorbidities of severe trauma,”
says Gupta.
Researchers are still in the early stages of developing this therapy. It is unknown whether it could apply to other brain injuries, such as chronic traumatic encephalopathy (CTE), a progressive degenerative disease linked to repetitive brain trauma that has received public attention in recent years.
This study opens possibilities for broader use of photomedicine. “Transcranial LED therapy is a promising research area that may help various brain disorders with limited treatment options,” says Margaret Naeser, Ph.D., a photomedicine researcher and research professor of Neurology at Boston University School of Medicine, who was not involved in the study.
Source: Massachusetts General Hospital
Journal reference: Longo, M. G. F., et al. (2020) Effect of Transcranial Low-Level Light Therapy vs. Sham Therapy Among Patients With Moderate Traumatic Brain Injury. doi.org/10.1001/jamanetworkopen.2020.17337
Further reading: NICHD Traumatic Brain Injury Overview
