“ There are lots of disorders of connectivity , mostly in psychiatry , where this intervention may have a role . PTSD , depression , autism : these are all promising areas for light therapy .”
Issue 33.3 SUMMER 2024
received light therapy within 72 hours of their injuries through a helmet that emits near-infrared light .
“ The skull is quite transparent to near-infrared light ,” said study co-lead author Rajiv Gupta , M . D ., Ph . D ., from the Department of Radiology at MGH . “ Once you put the helmet on , your whole brain is bathing in this light .”
The researchers used an imaging technique called functional MRI to gauge the effects of the light therapy . They focused on the brain ’ s 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 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 and the late-subacute phase of three months after injury .
Of the 38 patients in the trial , 21 did not receive light therapy while wearing the helmet . This was done to serve as a control to minimize bias due to patient characteristics and to avoid potential placebo effects .
Patients who received low-level light therapy showed a greater change in resting-state connectivity in seven brain region pairs during the acute-to-subacute recovery phase compared to the control participants .
“ There was increased connectivity in those receiving light treatment , primarily within the first two weeks ,” said study coauthor Nathaniel Mercaldo , Ph . D ., a statistician with MGH . “ 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 .”
The precise mechanism of the light therapy ’ s effects on the brain is also still to be determined . Previous research points to the alteration of an enzyme in the cell ’ s mitochondria ( often referred to as the “ powerhouse ” of a cell ), Dr . Gupta said . This leads to more production of adenosine triphosphate , a molecule that stores and transfers energy in the cells . Light therapy has also been linked 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 study coauthor Suk-tak Chan , Ph . D ., a biomedical engineer at MGH .
While connectivity increased for the light therapy-treated patients during the acute to subacute phases , there was no evidence of a difference in clinical outcomes between the treated and control participants . Additional studies with larger cohorts of patients and correlative imaging beyond three months may help determine the therapeutic role of light in traumatic brain injury .
The researchers expect the role of light therapy to expand as more study results come in . The 810-nanometer-wavelength light used in the study is already employed in various therapeutic applications . It ’ s safe , easy to administer and does not require surgery or medications . The helmet ’ s portability means it can be delivered in settings outside of the hospital . It may have applications in treating many other neurological conditions , according to Dr . Gupta .
“ There are lots of disorders of connectivity , mostly in psychiatry , where this intervention may have a role ,” he said . “ PTSD , depression , autism : these are all promising areas for light therapy .” g
“ There are lots of disorders of connectivity , mostly in psychiatry , where this intervention may have a role . PTSD , depression , autism : these are all promising areas for light therapy .”
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