How Using Red Light Therapy Improves Cognitive Function
Photobiomodultaion, also known as RLT, is being used as a treatment for neurodegenerative diseases, but also for brain enhancement as well.
One of my biggest fears about getting older is developing dementia or Alzheimer’s disease. To that end, I try to keep my brain health and engaged. However, if these diseases do development photobiomodulation offers a treatment modality. There are significant, sometimes dramatic, improvements in the treatment of neurodegenerative diseases, such as Alzheimer’s, dementia and Parkinson’s, along with Traumatic Brain Injuries (TBI) with photobiomodulation.
For all the information presented in this article the following terms; Red Light Therapy, RLT, photobiomodulation, and PBM mean one and the same, and may be used throughout the text interchangeably.
Light On The Brain
There are three broad categories of brain disorders where PBM has been successfully used. First are traumatic events that consists of; injuries from impact, concussions, and strokes. Next are degenerative diseases such as Alzheimer’s, dementia and Parkinson’s. Finally, there are psychiatric issues such as anxiety, depression, and PSD. (Study)
Not surprisingly, since PBM has been so helpful with brain disorders, that it provides a measure of cognitive enhancement in normal, healthy people.
In most brain studies the PBM wavelength of light used is Near Infrared (NIR). Some researchers had used lasers, but most are using LEDs today. The NIR LED is typically fashioned into a brain cap, which allows the light to be administered to the forehead.
“Photobiomodulation and the Brain” edited by Dr. Michael Hamblin and Ying-Ying Haung. This ebook contains dozens of clinical studies by scientist across the globe that focus on Red Light Therapy and its effect on the brain. The ebook is 656 pages long, the first 125 pages are available on Google books.
Light Penetration
The first question scientists ask was how much light would penetrate the scalp and skull to radiate the brain. Scientists used a few methodologies to measure light penetration, NIR spectroscopy and human cadaver heads with their soft tissues intact. On average, 5% of NIR gets through to the brain at a depth of 23 millimeters.
Red light, on the other hand (650 nm) doesn’t penetrate well at all.
And certain wavelengths of NIR penetrate deeper than others, 808 nm has a penetration depth of 4–5 cm.
How it works
This is not a definitive answer, more like what we know so far. Cells contain photoreceptor molecules or chromophores that absorb light and by doing so stimulate the cell’s mitochondria’s metabolism. This process is responsible for PBM’s positive effects; increased blood flow, improved cell metabolism, improved ATP production and mitochondrial activity.
Researchers studying the brains of experimental animals that suffered acute brain injury, learned PBM treatments on the brain can initiate effects that last days, weeks and even months. Obviously something more is happening than a transitory effect when the brain is being illuminated with NIR. Scientists feel that the PBM activates signaling pathways and transcription factors that cause changes in protein expression.
It’s Not All In The Head
Scientist questioned whether it was only the light on the head, causing the positive neurological effects. So using mouse models with Parkinson’s disease, they ran studies that block the RLT light from entering the head, but allowed the RLT light to enter the body.
Even with the head block from RLT light, the mice exhibited positive neurological effects, although not as pronounced as when the skull was illuminated.
Similar work was carried out using mice models for Alzheimer’s Disease.
What this shows is that RLT on the body will provide some degree of neurological protection for the brain.
Improvements in Memory and Cognition
Numerous clinical studies prove that consecutive treatments of shining Near InfraRed light on the head, call transcranial PBM, of subjects diagnosed with dementia shown improvement in executive function, recall, visual attention as well as improved EEG amplitude. (study), (study), (study). In at least one case, the subject’s sense of smell returned. (study)
This is just a smattering of studies, there is more clinical evidence available to read on PubMed. (study)
TBI and Reaction Time
Traumatic Brain Injury (TBI) is another field where the results of PBM treatments show a marked improvement. In mild TBI cases, say a sports concussion, the reaction time of the individual is compromised and slower. In a study, 31 healthy volunteers between the ages of 14 and 65 underwent a qEEG reaction time test, before and after a 20 minute NIR PBM treatment. The treatment provided about 20J/cm² to the head.
The reaction time of the treated group improved by 24 msec as compared to the controls.
Treatment of Depression
This clinical study shows improvements in patients with major depressive disorder. The treatment consisted of NIR at a wavelength of 823 nm, the total power provided to the head was up to 65J over a 20–30 minute session, twice a week, for eight weeks.
The conclusion reached by the researchers are that the Near Infrared light treatments provided antidepressive properties with a medium to large effect, with no adverse side effects. (Study)
Improvements in Cognition and Reaction Time In the Elderly
This study was to measure the effects of PBM on age-related cognitive decline. Using thirty test subjects broken into two groups; a treatment group (n=15) and control group (n=15). The treated group received a 7.5 minute treatment using 633nm and 870nm delivered to the skull using three LED diode arrays. In total 1349 J of energy was delivered. If we average at a 5% transmission through the skull, that would be about 67.5 J.
The results were that the treatment group reaction time was significantly faster than the control group. Verbal fluency also increased significantly in the treated group. (study)
Improvements in Cognition and Reaction Time In Young Adults
This is a meta-analysis of nine studies that show cognitive improvements in young adults. (Study) The full data for this study is scheduled to be released in Oct 2020.
Going Further
Much of the research points to using Near InfraRed wavelengths 810–850 nm and longer for the brain. This is one area where a few studies have shown that pulsing the near infrared light around 10 hz improves the effect.
Although the data shows a bit of neurological protection for the brain with RLT body illumination.
Having worked with electronics for the better part of my career, the fabrication of a basic device using an athletic sweat band, to hold a few NIR LED’s to the forehead and skull will not be difficult. Although I don’t know if Medium allows simple electronic how-to article. If there is sufficient interest, I will write it.
