By Charles Bankhead , Staff Writer, MedPage Today
Reviewed by Robert Jasmer, MD; Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, RN, BC-ADM, CDE, Nurse Planner
March 20, 2011-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 (Stroke. 2007;38:1843-1849, Stroke. 2009;40:1359-1364). 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 (Behav Brain Funct. 2009;5:46).
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.
The investigators have used two different devices that have FDA approval for treatment of musculoskeletal pain. The light therapy is delivered via diodes attached to the forehead and scalp. During each treatment session, a total energy of 500 mW is applied, distributed 22.2 mW/cm2 (13.3J/cm2 at the scalp and an estimated 0.4J/cm2 at the cortex).
The first patient treated had a closed-head TBI resulting from an automobile accident in 1997. She did not begin treatment until seven years later. Neurocognitive testing two years after the accident showed that her reasoning, verbal, and executive function skills all remained significantly impaired.
The initial treatment session lasted five minutes. The days after treatment, the patient reported that her concentration and focus had improved, such that she could work continuously at her computer for 40 minutes, compared with 20 minutes before treatment.
The treatment time and parameters increased gradually, and by eight weeks, the patient was able to work continuously at her computer for three hours at a time.
The patient received a home unit after seven months and began nightly, self-administered therapy. Treatment usually occurs at bedtime because she has found that the LED protocol has improved her sleep, the authors noted.
The second patient, a retired military officer employed as a technology consultant, had a history of multiple concussions without loss of consciousness.
When she self-referred for neuropsychological evaluation in 2009, she complained of changes in cognitive function over the previous two years, but most noticeably during the past four to five months. She had quit working and received medical disability for seven months.
Neurocognitive testing showed multiple deficits in executive functioning, including working memory, processing speed, and cognitive flexibility, consistent with frontal-lobe dysfunction. MRI scans revealed several abnormalities involving the frontal lobe.
After four months of transcranial LED therapy, the patient discontinued medical disability and returned to work and has continued to work regularly. Follow-up neuropsychological testing showed significant improvement from baseline on tests of executive function and inhibition and memory.
The second patient also met diagnostic criteria for PTSD prior to beginning transcranial LED therapy. Within a few months of starting daily therapy, she reported improved sleep and reduced impulsivity, irritation, and anger.
The authors reported that both patients have shown regression of improvements in cognitive dysfunction within one to two weeks of stopping the transcranial LED therapy.
Further study is required to determine optimal treatment parameters, Naeser and her colleagues concluded.
They also recommended that future studies include pre- and post-neuropsychological testing, as well as functional brain imaging and diffusion tensor imaging scans, to better understand the possible physiological changes that may take place with the therapy.