Of Mice and Men: New Light and Sound Combination Therapy May Treat Alzheimer's

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As of 2018, 5.7 million Americans are living with Alzheimer's disease, the pervasive brain disorder that causes eventual deterioration of cognitive, physical and behavioral abilities. While Alzheimer's patients can be treated for symptoms or pain, the disease has no cure, and no current treatment can slow its progression.

Recently published research by Massachusetts Institute of Technology (MIT) neuroscientists, however, indicates that amyloid plaques could be reduced via brain wave stimulation. “By exposing mice to a unique combination of light and sound, MIT neuroscientists have shown that they can improve cognitive and memory impairments similar to those seen in Alzheimer’s patients,” quotes MIT News.

Initial research on the benefits of LED light therapy in the treatment of Alzheimer's was reported in December of 2016, senior-authored by Li-Huei Tsai, the Picower Professor of Neuroscience, director of MIT’s Picower Institute for Learning and Memory. “Using LED lights flickering at a specific frequency, MIT researchers have shown that they can substantially reduce the beta-amyloid plaques seen in Alzheimer’s disease, in the visual cortex of mice. This treatment appears to work by inducing brain waves known as gamma oscillations, which the researchers discovered help the brain suppress beta-amyloid production and invigorate cells responsible for destroying the plaques.”

As the effects of the light therapy were limited to the visual cortex in the earlier study, this time around, "the researchers set out to explore whether they could reach other brain regions, such as those needed for learning and memory, using sound stimuli. They found that exposure to one hour of 40-hertz tones per day, for seven days, dramatically reduced the amount of beta-amyloid in the auditory cortex (which processes sound) as well as the hippocampus, a key memory site that is located near the auditory cortex."

Tsai explained that “what we have demonstrated here is that we can use a totally different sensory modality to induce gamma oscillations in the brain. And secondly, this auditory-stimulation-induced gamma can reduce amyloid and Tau pathology in not just the sensory cortex but also in the hippocampus.”

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When combining both light and auditory stimulation, the researchers discovered an even greater effect. “The combined treatment led to fewer A-beta plaques across a big stretch of the brain, including the hippocampus and the prefrontal cortex, an area important for complex thinking. What’s more, the microglia seemed to swarm into a feeding frenzy.” Tsai added that “Microglia pile up on each other, all congregated around the amyloid plaques.”

A Biospace interview with Keith Fargo, Ph.D., Director of Scientific Programs & Outreach at the Alzheimer's Association, illuminated potential future effects of the study. “I think it’s a really interesting idea. I think that the most important thing for people to know is that it’s not ready for primetime yet. It’s preliminary. We wouldn’t want anyone to expose their families to flickering lights or buzzing noises. We don’t know if there’s going to be any benefit,” he began.

“I think that [the study] also raises the question of how would you actually make it work in a human situation? It’s not outside of the realm of possibility that something like this could be beneficial. If you look at Parkinson’s, for example, implants have proven to be an effective treatment,” he continued.

When discussing other current research being done on Alzheimer's treatments, Fargo explained that “the medications we have now for Alzheimer's are not disease-modifying; they treat symptoms. I like the analogy of cancer. If you have pain from a symptom of cancer, we can stop your pain, but we can’t do anything for the cancer. That’s where we’re at for Alzheimer's. We have medications that are symptomatic, but we can’t treat the disease, and it ultimately leads to death. People are highly invested today in treatments that are disease modifying. Most of the clinical trials today are for disease-modifying therapeutics. If anything else works, that’s great. If synchronized firings in the brain work, that’s amazing for the future of the disease.”

As to why this light and sound therapy has been effective, researchers are stumped. A recent Scientific American article outlines that ‘Researchers simply do not know why these brain waves, specifically ones rising from light and sound stimulation at 40 hertz and no other frequencies, can lead to a reversal of Alzheimer’s disease symptoms. “That’s a mystery,” says Terrence Town, a neuroscientist, at the University of Southern California who was not involved with the work. It’s also not clear if these beneficial effects would appear or if 40 hertz is the “magic” frequency in humans, he says.’

When asked to comment on this, Fargo stated that “I would agree that it’s a mystery. That doesn’t mean it doesn’t work, especially if you think about exactly why it works. One of the most widely used things in medicine is anesthesia, and no one knows exactly why it works. But it does, and it’s used frequently in major surgeries.”

Tsai and her colleague Ed Boyden are currently advancing human studies at their start-up, Cognito Therapeutics, hoping to eventually answer that question of why light and sound have served as an effective Alzheimer's treatment in mice. So far, she quotes that “Nobody gets sick or even complains about it. But to see a [therapeutic] effect in humans, you’ll have to wait a long time. If this approach has an impact, the experiment could easily take five years to have some conclusive answer.”

Separately, when asked about the Alzheimer's Association plans to further fund research, Fargo added that “we fund research across the gamut for any type of treatments and are interested in funding all kinds of treatments.”

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