Brain Health

Light Therapy Boosts Connectivity for Those With Brain Injury

Medical experts have been using light therapy—including ultraviolet and infrared wavelengths—to promote wound healing for years. But recently, a team of researchers at Massachusetts General Hospital set out to test low-level light therapy on patients with traumatic brain injury to see if the therapy could increase brain connectivity.

The Research

The team recruits 38 patients with moderate traumatic brain injury, defined as an injury serious enough to alter cognition or be visible on brain scans. Of the 38 participants, 17 received light therapy (810-nanometer-wavelength light) while wearing a helmet that bathes the brain in light because the skull is somewhat transparent to near-infrared light.

The other 21 participants, who made up the control group, did not receive the light therapy via helmet in order to minimize bias due to patient characteristics and to avoid potential placebo effects.

The scientists used functional MRI (fMRI) to measure the effects of the light therapy, focusing on the brain’s resting-state functioning connectivity in which brain regions communicate while not engaged in a specific task. They looked at MRI results during three recovery phases:

• the acute phase of within one week after injury

• the subacute phase of two to three weeks post-injury

• the late-subacute phase of three months after injury

The Results

The patients who underwent the light therapy demonstrated a greater change in resting-state connectivity in seven brain region pairs *during the acute-to-subacute recovery phase) compared to the control group.

“There was increased connectivity in those receiving light treatment, primarily within the first two weeks,” explains the study coauthor, Massachusetts General Hospital Statistician Dr. Nathaniel Mercaldo. “We were unable to detect differences in connectivity between the two treatment groups long term, so although the treatment appears to increase the brain connectivity initially, its long-term effects are still to be determined.”

Why does light therapy seem to increase brain connectivity? Although nothing has been cemented ins tone, previous research seems to indicate that the light alters an enzyme in mitochondria, leading to an increase in adenosine triphosphate production. Adenosine triphosphate, sometimes referred to as the “molecular unit of currency,” is a nucleotide that provides energy to living cells.

Additionally, light therapy is associated with anti-inflammatory effects and blood vessel dilation.

Because there was no evidence of differences in clinical outcomes between the two groups, more studies will need to be done. Future studies will need to include larger cohorts and imagine beyond three months in order to help determine the long-term therapeutic effects of light therapy for TBIs.

“There are lots of disorders of connectivity, mostly in psychiatry, where this intervention may have a role,” says study co-lead author Dr. Rajiv Gupta of Massachusetts General Hospital’s Department of Radiology. “PTSD, depression, autism: these are all promising areas for light therapy.”

The study was published in the May 28, 2024 edition of the journal Radiology.

MBJ

Wendy Burt-Thomas writes about the brain, mental health and parenting.

Check out the original research:

https://pubs.rsna.org/doi/10.1148/radiol.230999

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