Low-level light therapy (LLLT) appears to promote healing in the brains of individuals with significant brain injuries, according to a study published in the journal Radiology.
For years, researchers have explored the wound-healing properties of light of various wavelengths. In a recent study, scientists at Massachusetts General Hospital (MGH) applied LLLT to 38 patients who had sustained moderate traumatic brain injuries (TBI). These injuries were severe enough to impair cognition and/or be detectable on brain scans. The therapy was administered within 72 hours post-injury using a helmet that emits near-infrared light.
Dr. Rajiv Gupta, M.D., Ph.D., from the Department of Radiology at MGH and co-lead author of the study, explained the choice of near-infrared light. “The skull is quite transparent to near-infrared light. Once you put the helmet on, your whole brain is bathing in this light,” he said.
To evaluate the impact of LLLT, the researchers employed functional MRI (fMRI), focusing on the brain's resting-state functional connectivity. This measures communication between brain regions when a person is at rest. MRI scans were taken during three phases of recovery: 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).
In the trial, 21 of the 38 patients served as a control group by wearing the helmet without receiving light therapy. This design aimed to minimize bias and control for placebo effects.
The findings revealed that patients who underwent LLLT exhibited greater changes 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,” noted Dr. Nathaniel Mercaldo, Ph.D., a statistician at MGH and co-author of the study. However, the researchers did not observe long-term differences in connectivity between the two groups. “Although the treatment appears to increase brain connectivity initially, its long-term effects are still to be determined,” added Mercaldo.
The exact mechanisms by which LLLT affects the brain remain under investigation. Previous research suggests that LLLT may alter an enzyme in the mitochondria, the cell's “powerhouse,” leading to increased production of adenosine triphosphate (ATP), which stores and transfers cellular energy. Additionally, LLLT has been associated with blood vessel dilation and anti-inflammatory effects. “There is still a lot of work to be done to understand the exact physiological mechanism behind these effects,” said Dr. Suk-tak Chan, Ph.D., a biomedical engineer at MGH and co-author of the study.
Despite the increase in brain connectivity during the early recovery phases, the study found no significant differences in clinical outcomes between the LLLT and control groups. Further research with larger patient cohorts and extended follow-up periods is needed to determine the full therapeutic potential of LLLT for TBI.
The study's authors anticipate that the role of light therapy will expand as additional research is conducted. The 810-nanometer-wavelength light used in this study is already employed in various therapeutic contexts. It is safe, non-invasive, and easy to administer, without the need for surgery or medications. The portability of the helmet allows for use in diverse settings, potentially extending its applications to other neurological conditions. “There are lots of disorders of connectivity, mostly in psychiatry, where this intervention may have a role,” Dr. Gupta suggested, citing PTSD, depression, and autism as promising areas for LLLT.
In summary, while low-level light therapy shows promise in enhancing brain connectivity following traumatic brain injury, further studies are required to fully understand its long-term benefits and underlying mechanisms.
Source: Radiological Society of North America