7 Studies Explain How Red Light Therapy Comforts Dementia
Photobiomodulation (red light therapy) can relieve dementia symptoms. After even one session, patients cry less, hug more, and remember better.
Photobiomodulation lends energy to the mitochondria, triggering several beneficial events that improve the emotional and cognitive symptoms of dementia. Seven of these effects are:
- improved metabolic functioning that energizes neurons
- increased cerebral blood flow that oxygenates tissues
- increased messenger oxidative species that reduce inflammation
- cyclo-oxygenas-2 (COX-2) inhibition suppressing pain in the same manner as NSAIDs
- increased neurogenesis replacing damaged and lost neurons
- increased synaptogenesis for greater cognitive function
- a theorized increase in stem cells aiding in neural damage recovery
This article is a partial summary of Photobiomodulation for Alzheimer’s Disease: Has the Light Dawned?, a 2019 article by Dr. Michael Hamblin published in Photonics.
#1 Photobiomodulation Increases Biological Battery (ATP) Production
Mitochondrial dysfunction is common to neurodegenerative diseases, including the various dementias such as Alzheimer’s. The mitochondria create adenosine triphosphate (ATP), which the brain uses to transport energy. A healthy brain with plenty of ATP can repair damaged tissues and create synaptic connections for cognitive function. A dementia brain loses the ability to repair itself when the mitochondrial ATP production fails.
With photobiomodulation (PBM, or red light therapy), photons delivered at low energy absorb in Complex IV of the mitochondria. Increased ATP production follows, which is believed to be because the electron transport chain uses the photon energy in place of electrons. The photon energy allows the mitochondria to pump ions to the outer part of the inner membrane. They flood into ATP Synthase where they power a molecular rotor that binds adenosine diphosphate (ADP) with inorganic phosphate to make ATP.
When neurons need energy for repair and neurogenesis, and synapses need energy for creating connections, the ATP phosphate bond breaks, releasing the energy the cells need to do work.
Contrary to the pictures in most biology books, brain cells host thousands of mitochondria. Red light therapy re-energizes cells by lending energy to these thousands of mitochondria inside the neurons.
The body has somewhere around ten trillion mitochondria. Red light therapy delivers low-energy photon energy to this huge array of receptors. Healing happens where the light shines.
Red light therapy doesn’t change cellular structures. It returns mitochondria to the energy-production state that existed before systems started to break down.
#2 Photobiomodulation Repairs Blood Vessels and Opens Blood Flow
The photon absorption at Complex IV dissociates nitric oxide from the protein cluster to the blood vessels. Nitric oxide triggers processes that smooth the endothelial wall, creating a supple response from the muscle that controls blood flow. The vessel dilates, allowing more oxygen and nutrition delivery to damaged brain tissue.
#3 Photobiomodulation Signals a Chronic Inflammation to Slow
Chronic inflammation is another hallmark of dementia. The immune system engages in a constant fight against the oxidative stress created during the production of ATP. Reactive oxygen species (ROS) escape the ATP production process, creating cellular damage. The immune system endlessly fights against the ROS’ damage, a fight that is counter productive, as it just damages more cells and provokes more inflammation.
One effect of photobiomodulation is its ability to trigger ROS in brief bursts to signal shutting down neuroinflammation. Although reactive oxygen species (ROS) are often thought of as being only destructive due to their role in oxidative stress, ROS are essential to proper brain function due to their messaging role within the cell.
Photobiomodulation triggers ROS bursts in small amounts that create retrograde signaling from the mitochondria to the cell nucleus. The ROS message transcription factors that then signal the immune system to shut down the constant flow of inflammatory and destructive responses to oxidative stress.
#4 Photobiomodulation Inhibits COX-2 as a Drug-Free Anti-Inflammatory
Another anti-inflammatory effect of photobiomodulation is inhibition of the cyclo-oxygenase-2 (COX-2) enzyme. Because COX-2 promotes inflammation, inhibiting its activity is anti-inflammatory.
One study showed that low-power delivery of 635 nm red light reduced COX-2 activity indirectly by reducing the production of reactive oxygen species (ROS). Researchers compared the effect to non-steroidal anti-inflammatory drugs (NSAIDs), the over-the-counter anti-inflammatory drug. However, photobiomodulation differs in that it has no stomach or kidney destruction side effects. PBM is a non-invasive and safer alternative for reducing inflammation.
Because neuroinflammation is so prevalent and destructive in dementia, this path to reducing inflammation is thought to be one of the reasons that dementia subjects recover cognitive abilities in photobiomodulation studies.
#5 Photobiomodulation Encourages Neurogenesis that Replaces Lost Neurons
Adult neurogenesis is the process of generating new brain cells in the adult brain. Neural stem cells (NSCs) and neuroprogenitor cells are capable of producing new neurons and glial cells in the adult brain. The brain has regenerative potential in neurogenesis because new neurons can replace those lost to the disease process.
At a minimum, the brain can use NSCs and neuroprogenitor cells to produce neurons and glial cells in the hippocampus and the lateral ventricles.
In a 2006 study, researchers induced strokes in rats, and then treated the rats with transcranial photobiomodulation. The rat brains grew new cells in the lateral ventricles where the brain was treated with photobiomodulation.
In another study, researchers induced traumatic brain injury in mice and then treated the mice with transcranial photobiomodulation., The mice had a significant increase in the markers for neurogenesis in the dentate gyrus and lateral ventricles.
As the hippocampus loses neurons and neurogenesis activity in dementia brains, photobiomodulation has the potential to restore neural function by supporting neurogenesis.
#6 Photobiomodulation Increases BDNF to Support Synaptogenesis and Cognition
In addition to the stem cell support for neurogenesis, photobiomodulation also upregulates production of brain derived neurotrophic factor (BDNF), nerve growth factor (NGF), neurotrophins that foster growth of new synapses. That means that brain cells can connect better, using neurotransmitters to communicate messages from sets of neurons to other sets of neurons. This activity is the basis for thinking, and so is a powerful effect of photobiomodulation.
Synapsin-1 is a protein that supports neural fiber and synaptic connections. BDNF supports synapsin-1 activity. When photobiomodulation upregulates BDNF, it promotes the growth of the neural fibers that connect brain cells together with the help of synpasin-1.
#7 Photobiomodulation Encourages Stem Cell Proliferation and Differentiation
The effects of photobiomodulation on dementia we’ve discussed so far are known to have benefit to people with dementia. The ATP, blood flow, BDNF, new neurons and synapses translate to cognitive, memory and emotional benefits.
The stem cell benefits are only theoretical at this point. PBM does encourage stem cell proliferation and differentiation, that is known and repeatable in experiments.
Evidence so far shows that photobiomodulation helps bones, kidney and heart cells heal after injury and disease. The stem cell differentiation grows bones, and repairs kidneys and hearts. What is not yet know is whether these activities translate to benefits for the dementia patient. It would be a reasonable theory that stem cell photobiomodulation would contribute to neurogenesis, an effect that remains to be tested.
Dr. Hamblin gives much more detail on the Alzheimer’s and other dementia benefits of photobiomodulation. We’ve discussed only seven of the many effects that PBM has on the neurodegenerative brain. These benefits include:
- improved metabolic functioning occurs in the mitochondria, increasing adenosine triphosphate (ATP) and reducing oxidative stress
- increased cerebral blood flow and oxygenation possibly triggered by the release of nitric oxide, resulting in oxygenation, nutrition and vascular smoothing (decrease atherosclerosis)
- neuroprotective effects protecting cells from early death, toxins and free radicals
- photobiomodulation improves a paradoxical “good” oxidative stress necessary to gain benefits from exercise, as an example; the reactive oxygen species act as messengers rather than as free radicals
- anti-inflammatory effects from the inhibition of cyclo-oxygenas-2 meaning that photobiomodulation has a similar effect as Ibuprofen
- neurogenesis was first detected in photobiomodulation in 2006 and has since developed into a traumatic brain injury treatment using only light therapy
- synaptogenesis occurs when photobiomodulation up-regulates brain derived neurotropic factor (BDNF), which is exactly the opposite of what happens in Alzheimer and concussive brains
- stem cell production that might contribute to neurogenesis.
Hamblin MR. Photobiomodulation for Alzheimer’s Disease: Has the Light Dawned? Photonics. 2019 Sep;6(3):77. doi: 10.3390/photonics6030077. Epub 2019 Jul 4. PMID: 31363464; PMCID: PMC6664299.