A study published in the journal “Radiology”, a journal of the Radiological Society of North America (RSNA), shows that low-level light therapy appears to affect healing in the brains of people who have suffered severe brain injuries.

How Light Therapy Helps With Traumatic Brain Injuries

The wound-healing properties of light of different wavelengths have been studied for years. Researchers at Massachusetts General Hospital (MGH) performed low-level light therapy on 38 patients who had suffered moderate traumatic brain injury. Low-level lasers are low-energy lasers and, unlike the well-known medical power lasers, are not used for surgical purposes but exclusively for healing purposes. A brain injury is a head injury serious enough to affect cognition and/or show up on a brain scan. Patients received light therapy within 72 hours of their injury through a helmet that emits near-infrared light. “The skull is fairly transparent to near-infrared light,” said study co-lead author Rajiv Gupta, M.D., Ph.D., of the Department of Radiology at MGH. “Once you put on the helmet, the entire brain is bathed in this light.”

The researchers used an imaging technique called functional MRI to measure the effects of light therapy. They focused on resting-state functional connectivity, the communication between brain regions that occurs when a person is at rest and not engaged in a specific task. The researchers compared the MRI results during three recovery phases: the acute phase within one week of the injury, the subacute phase two to three weeks after the injury, and the late-subacute phase three months after the injury. Of the 38 patients in the study, 21 did not receive light therapy while wearing the helmet. This served as a control to minimize bias due to patient characteristics and to avoid possible placebo effects.

Patients who received low-intensity light therapy showed a greater change in connectivity (interaction of individual brain regions) at rest in seven brain region pairs during the acute to subacute recovery phase compared to the control participants. “In the patients who received light therapy, connectivity was increased, especially in the first two weeks,” said study co-author Nathaniel Mercaldo, Ph.D., a statistician at MGH. The researchers found no differences in connectivity between the two treatment groups in the long term. So although the treatment seems to initially increase brain connectivity, its long-term effects are not yet known.

Can be Used for Other Areas as Well

The exact mechanism of light therapy’s effects on the brain is also not yet clear. Previous research suggests a change in an enzyme in the cell’s mitochondria (often referred to as the “powerhouse” of a cell). This results in higher production of adenosine triphosphate, a molecule that stores and transfers energy in cells. Light therapy has also been associated with vasodilation and anti-inflammatory effects. While connectivity increased in patients treated with light therapy during the acute to subacute phase, there was no evidence of a difference in clinical outcomes between treated and control participants. Additional studies with larger patient cohorts and correlative imaging over a period of more than three months could help determine the therapeutic role of light in traumatic brain injury.

The researchers expect that the role of light therapy will increase as more study results become available. The 810-nanometer wavelength light used in the study is already being used in various therapeutic applications. It is safe, easy to administer, and requires no surgery or medication. Because the helmet is portable, it can be used outside the hospital. According to Dr. Gupta, it could also be used to treat many other neurological disorders. These include PTSD, depression, and autism, among others. All of these disorders are promising areas for light therapy.