Two patients with long-term deficits from traumatic brain injury (TBI) have shown substantial improvement in cognitive function with transcranial light therapy, investigators reported.A TBI patient on medical disability returned to work as a technology consultant after four months of nightly, at-home treatment with near-infrared light-emitting diodes (LEDs) placed on the forehead and scalp,Seven years after a closed-head TBI, another patient experienced improved sustained attention capability from 20 minutes to three hours with ongoing LED treatment.
Both patients regressed with discontinuation of the light therapy, Margaret A. Naeser, PhD, of Boston University and the Veterans Affairs Boston Healthcare System, and colleagues reported online in Photomedicine and Laser Surgery.”Results from the two chronic TBI cases described here, along with those from previous [light therapy] studies with acute stroke patients and chronic, major depression cases, suggest that further, controlled research with this methodology is warranted,” Naeser and her co-authors wrote in conclusion.
“Transcranial red/near-infrared LED may be an inexpensive, noninvasive treatment, suitable for home treatments, to improve cognitive function in TBI patients, as well as to reduce symptom severity in post-traumatic stress disorder,” they added.
In patients with closed-head, mild TBI, CT or MRI scans usually show no evidence of focal lesions, but more often, diffuse axonal injury in the anterior corona radiata and frontotemporal regions.PET scans of the brain have shown reduced regional glucose metabolism in bilateral frontal and temporal lobes in chronic TBI, the authors wrote. Other studies have shown abnormal frontal-lobe activation.
Frontal-lobe regions susceptible to TBI-related damage include the prefrontal cortex and the anterior cingulate gyrus. The former is involved in maintaining working memory, especially sustained attention. The anterior cingulate gyrus has been implicated in divided attention, working memory, and memory retrieval among other functions.
Low-level laser therapy has been shown to have beneficial cellular and physiologic effects in controlled trials, the authors continued.Absorption of laser light has been associated with increased cellular respiration, intracellular calcium flux, increased ATP synthesis, increased nerve-cell proliferation and migration, and NF-κB activation.
Transcranial infrared light has been shown to reduce brain damage in preclinical models of stroke, improve memory in middle-aged mice, and improve outcomes in clinical stroke . Low-level light treatment has stimulated neuronal repair in an animal model of spinal-cord injury.
Low-level laser therapy also increases expression of various growth factors that could induce neurogenesis in TBI. Studies involving patients with chronic major depression showed significant improvement in depression and anxiety for two weeks after a single light treatment.Given the experimental and clinical evidence supporting therapeutic benefits of light therapy in TBI, Naeser and colleagues have evaluated transcranial near-infrared/LED light as a means of improving cognitive function in patients with chronic TBI.