Could memory and cognitive loss from age-related dementia be treated simply by looking at light flashes and listening to a low-pitched buzzing sound? Scientists say YES! (At least, in tests on laboratory mice.)
An article that appeared in Cell magazine in March 2019 revealed that exposing mice to flashing light and pulsing sounds – both tuned to the frequency 40 hertz – reversed key symptoms and pathology of Alzheimer’s disease.
Mice exposed to the monotonous droning buzz of 40 Hertz – a sound barely high enough for humans to hear – for one hour a day for a week “reduced levels of beta-amyloid in the auditory cortex and nearby hippocampus, a part of the brain responsible for learning and memory. Stimulated mice performed better on memory tasks, including recognizing objects and navigating a water maze to find a hidden platform. Researchers also saw changes in activation responses in microglia and astrocytes, cells involved in clearing debris, and in blood vessels.”
North Carolina’s Wake Forest School of Medicine neuroscientist Shannon Macauley explained that most new treatments for dementia have not made it past the clinical trials. Although not involved in this work, she found this discovery praiseworthy:
“I think it’s an absolutely fascinating paper, to be honest. It’s a very provocative idea. It’s a noninvasive and easy and low cost, potentially, so if it were to come to fruition in humans — that’s fabulous.”
If you are healthy, all sensations, movements, thoughts, memories, and feelings you experience are the consequence of bioelectrochemical signals that course through a complex network of brain neurons (nerve cells).
Normally, the tens of billions of neural cells use electrical and chemical signals to relay messages between different parts of the brain and between the brain and all the body’s muscles and organs.
Neural electrical charges travel along axons (nerve fibers) and trigger the release of chemicals across tiny gaps (synapses) to neighboring neurons to ensure constant communication with each other.
Every thought, feeling, and motion humans experience is due to this highly sophisticated and elegant internal signaling system.
Over time, however, neurons begin to fail and stop communicating. As neurons die, the brain actually shrinks in size. Older people tend to start losing their long- and short-term memory, have trouble thinking and making decisions, experience speech problems, and may lose the ability to function independently.
Alzheimer’s disease is the frequent cause of dementia (mental decline) in Western nations and it is incurable. An estimated 5.5 million people are affected in the U.S. by Alzheimer’s and the frequency is expected to double every 20 years until 2040.
Patients with Alzheimer’s typically have an imbalance of neural cells because of destructive toxic changes in the brain. As the disease progresses, brain cells that process, store, and retrieve information degenerate and die.
It can take years or decades before the first recognizable signs of dementia appear. People with Alzheimer’s – as well as their families and friends – may grow frustrated from forgetfulness, memory loss, and other disabilities that hallmark this age-related cognitive decline.
The researchers who experimented with using light and sound to treat Alzheimer’s in mice divided their test subjects into groups and altered them genetically to produce the main symptoms.
In one batch of mice, neurofibrillary tangles were formed inside their neurons. These are dysfunctional knots of a protein called tau that can cause cell death.
A second group of lab mice was altered to develop amyloid-beta plaques. These sticky heaps of protein pile up and block the flow of communication between neurons.
All the mice were also afflicted with a third signature disease symptom: irregular brain activity in the gamma range of brain waves that oscillate between 30 and 100 times a second.
Brain waves are produced when large neural clusters oscillate on and off in sync. This rhythmic electrical flutter is how neurons encode our thoughts, actions, and senses.
Neuroscientist Li-Huei Tsai, director at the Picower Institute for Learning and Memory at Massachusetts Institute of Technology (MIT), was testing brain activity in mice in 2015 by flickering a strobe light operating at 40 hertz (40 times a second) at them. When she did so, the rodents’ brains flickered back.
What surprised Tsai was that the dissected brains of these mice had exceptionally low levels of amyloid plaques and tau tangles:
“It was the most remarkable thing. The light flicker stimulation triggers a tremendous microglia response. These are the brain’s immune cells that clear cell debris and toxic waste including amyloid. They’re impaired in Alzheimer’s disease, but [the light] seems to restore their abilities.”
“The result was so mind-boggling and so robust, it took a while for the idea to sink in, but we knew we needed to work out a way of trying out the same thing in humans.”
Further studies showed that combining strobe light therapy with sound therapy dramatically cleared plaques in several brain areas in lab mice, including in the prefrontal cortex.
Tsai and her colleague Ed Boyden, a fellow neuroscientist at MIT, founded a company called Cognito Therapeutics in Cambridge, Massachusetts, to test light and sound treatments on humans. In 2018, the duo began a safety trial where 12 people with Alzheimer’s wore a flickering strobe light device like a pair of glasses.
Tsau prescribed patience while waiting for the results of human testing because it could easily take five years to arrive at conclusive answers as to the effectiveness of treating Alzheimer’s with light and sound.