Cross-section of a mouse brain highlighting neurons that appear to release molecules that increase toxin clearance
Tsai Laboratory/MIT Picower Laboratory
A new explanation has emerged for why an experimental treatment for Alzheimer’s disease that involves flickering sounds and lights may help slow cognitive decline. This frequency appears to strengthen the brain’s waste processing network, helping to remove beta-amyloid and other toxic proteins that contribute to memory and concentration issues.
“Once we understand the mechanism, we can probably understand how to further optimize this whole concept and improve its effectiveness,” he says. Cai Li Hui at Massachusetts Institute of Technology.
The treatment involves exposure to light that flashes at a frequency of 40 times per second, or 40 hertz, and to a bass sound, also at 40 hertz. Typically, stimulation is given for one hour per day.
The key to this new approach is that large networks of brain cells naturally fire in sync with each other at different frequencies, known as brain waves. Brain waves around 40 Hz are common when people are concentrating and forming or accessing memories.
In 2016, Tsai’s team wondered if 40Hz stimulation could enhance cognitive performance in Alzheimer’s patients, since visual or auditory stimulation at a certain frequency is known to enhance brain waves at that same frequency. I decided to investigate.
Their group and other researchers have shown that this reduces amyloid accumulation in mice with Alzheimer’s disease and has cognitive benefits. Small trial in people with this condition, an even larger trial is underway. However, it is unclear how this treatment works, and another idea is that it boosts the function of immune cells in the brain.
Well, the special light and sound appears to work by enhancing the function of the brain’s drainage system, also known as the glymphatic system.
In the latest study, Tsai’s team conducted a series of experiments to study the mechanism of treatment in mice that were genetically modified to have amyloid buildup that normally occurs with age and to have worse memory than typical mice. carried out.
As expected, when the animals were exposed to light and sound, the amount of amyloid decreased. The new findings were that during treatment, the amount of cerebrospinal fluid entering the brain increased, and the amount of waste fluid leaving the brain through the glymphatic vessels increased.
This appears to occur because nearby blood vessels pulsate more, which may help glymph fluid flow through the blood vessels, allowing more water to flow into the glymph system.
The research team also found that the activity of a particular type of brain cell known as an interneuron appears to cause an increase in glymph flow by releasing a molecule called vasoactive intestinal peptide. When the research team chemically blocked the production of this molecule, the treatment no longer accelerated amyloid clearance.
Miken Nedergaard A professor at the University of Rochester in New York who helped discover the glymphatic system says the discovery is consistent with what we already know about it. “The brain, blood, and cerebrospinal fluid are all contained within the skull. When the blood volume expands, the brain tissue cannot be compressed, so the cerebrospinal fluid volume must also move.”
In the accompanying article natural medicineDr. Nedergaard says that a better understanding of the mechanisms of toxin removal in the brain “could be the key to unlocking that.” [their] Treatment Possibilities.”
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Source: www.newscientist.com
