Near-Infrared Light Therapy Improves Brain Connectivity in Patients With TBI
Key Findings
- Research has shown that near-infrared light therapy could help patients with moderate traumatic brain injury (TBI) by reducing the effects of the injury
- In a new study, a team of researchers at Massachusetts General Hospital shed light on the impact of the therapy on resting-state functional connectivity in the brain
- The findings could help open the door to application of near-infrared light therapy in disorders of connectivity
A new study by a team of researchers from the Wellman Center for Photomedicine and the Department of Radiology at Massachusetts General Hospital underscores the potential of near-infrared light therapy in mitigating the effects of traumatic brain injury (TBI). The researchers reported the study in the May 2024 issue of Radiology.
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Near-infrared light therapy is currently used for various biomedical applications, including muscle function improvement during rehabilitation and wound healing. The method offers a variety of benefits over other possible treatments in these areas. It is safe and noninvasive, and because the technology is portable and can be operated by non-specialists, the therapy can be delivered at any number of point-of-care locations outside of the hospital.
While the precise mechanism by which light therapy works is not yet fully understood, research points to changes in an enzyme in the cell's mitochondria that lead to increased production of adenosine triphosphate, a molecule that stores and transfers energy in the cells. The therapy has also been linked to improved blood flow and anti-inflammatory effects.
Measuring the Impact on Resting-State Functional Connectivity
In the study, the Mass General researchers focused on light therapy's demonstrated ability to modulate recovery in patients with TBI. Specifically, they sought to understand better the impact of light therapy on the functional connectivity of the brain when at rest.
The study enrolled 38 patients with moderate TBI. Of these, 21 underwent light therapy within 72 hours of their injuries (the remaining 17 served as controls). Using the imaging technique functional MRI, the researchers measured the effects of the light therapy by looking at the brain's resting-state functional connectivity—that is, the correlations between regions of the brain when a person is at rest and not engaged in a specific task.
They compared the results of the MRI scans during three recovery phases: the acute phase (within one-week post-injury), the subacute phase (two to three weeks post-injury), and the late-subacute phase (three months post-injury).
The study showed in the patients who underwent light therapy a greater change in resting-state connectivity during the acute-to-subacute recovery phase compared to the control participants, but not during the late-subacute phase.
"There was increased connectivity in those receiving light treatment, primarily within the first two weeks," said co-lead authors Suk-tak (Phoebe) Chan, PhD, a researcher in the Athinoula A. Martinos Center for Biomedical Imaging at Mass General, and Nathaniel Mercaldo, PhD, a statistician at Mass General. "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."
Overall, the study confirmed that light therapy does have an impact within the first three months of recovery in patients with moderate TBI. While the full clinical implications of its effects are not yet clear, the researchers believe that future studies with larger cohorts of patients and follow-up imaging for more than three months can help in realizing the therapeutic potential of the therapy.
"There are lots of disorders of connectivity, mostly in psychiatry, where this intervention may have a role," said Rajiv Gupta, MD, PhD, vice chair for clinical operations in the Mass General Department of Radiology, medical director for MGB Enterprise Neuroradiology, and co-senior author of the study with Benjamin Vakoc, PhD, of the Wellman Center for Photomedicine. "PTSD, depression, autism: these are all promising areas for light therapy."