Light Therapy for Brain Injuries

Research has long examined how different wavelengths of light aid wound healing. A recent study in the journal Radiology indicates that low-level light therapy (LLLT) may also help heal significant brain injuries. Massachusetts General Hospital researchers conducted LLLT on 38 patients with moderate traumatic brain injuries, which affect cognition or show up on brain scans. Using a helmet that emits near-infrared light, they administered the therapy within 72 hours of injury.

“Near-infrared light penetrates the skull well,” said Dr. Rajiv Gupta, co-lead author from the Department of Radiology at Mass General. “The helmet bathes the entire brain in light.” The researchers used functional MRI to measure the therapy’s impact, focusing on the brain’s resting-state functional connectivity—communication between brain regions when at rest.

They compared MRI results across three recovery phases: acute (within one week), subacute (two to three weeks), and late-subacute (three months). Of the 38 patients, 21 did not receive light therapy to serve as controls. Patients who received LLLT showed greater changes in resting-state connectivity in seven brain region pairs during the acute-to-subacute phase compared to the control group.

“Increased connectivity was seen mainly in the first two weeks,” said study coauthor Nathaniel Mercaldo, Ph.D. The next step is to study long-term effects. The exact mechanism of LLLT’s effect on the brain remains unknown, but previous research suggests it alters an enzyme in the cell’s mitochondria, leading to more production of adenosine triphosphate (ATP), a key energy molecule. LLLT is also associated with blood vessel dilation and anti-inflammatory effects.

The 810-nanometer-wavelength light used in the study is safe, easy to administer, and does not require surgery or medications. The helmet’s portability allows for use outside hospital settings. According to Dr. Gupta, LLLT may help treat other neurological conditions, such as PTSD, depression, and autism. As more research emerges, the role of light therapy is likely to expand.

(SOURCE: Radiology, published by the Radiological Society of North America)

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