RE: Oooh alzheimers9 Oct 2021 16:39
Hi Thoth - from an article in New Scientist July 2020:
Alzheimer’s disease may be caused by the abnormal build-up of a protein in the gut that then spreads to the brain, according to research in mice.
In people with Alzheimer’s disease, a protein known as beta-amyloid clumps together in the brain to form plaques that disrupt normal brain processes. Beta-amyloid deposits have also been found in the guts of people who died with the condition, but these have been largely overlooked.
John Rudd at the Chinese University of Hong Kong and his colleagues wondered if the beta-amyloid found in the brains of people with Alzheimer’s disease may have originated in their guts.
To test this idea, the researchers injected small amounts of the protein into the gastrointestinal tracts of mice. The beta-amyloid had a fluorescent marker attached so it could be traced.
The protein was rapidly taken up by the complex cluster of neurons that line the guts, which are sometimes referred to as the body’s “second brain”. One year later, the beta-amyloid had migrated up the vagus nerve, which connects the gut and the brain, and into the brains of the mice.
After the protein entered the brains, the mice displayed short-term and long-term memory problems similar to those seen in people with Alzheimer’s disease (The Journal of Physiology, doi.org/d35r).
The exact role that beta-amyloid in the brain plays in causing Alzheimer’s symptoms is still unclear, but if the protein is migrating there from the gut in people, it might be possible to prevent or delay the condition by removing beta-amyloid before it spreads to the brain, says Rudd. “Even if only some of the beta-amyloid load in the brain comes from the gastrointestinal tract, stopping or slowing that could give people an extra one or two years,” he says.
Bryce Vissel at the University of Technology Sydney in Australia says the idea is plausible, but needs more evidence to back it up. “Alzheimer’s disease can probably be caused in a number of different ways, so maybe a subset of Alzheimer’s could arise through some mechanism like this, but it’s just an intriguing possibility at this stage,” he says.
One question is why beta-amyloid might accumulate in the gut in the first place. In the brain, growing evidence suggests that plaques of the protein form to trap harmful bacteria and viruses that migrate from other parts of the body. This may explain why people with bacterial gum disease and herpes simplex virus are more likely to develop Alzheimer’s disease.
Beta-amyloid may also be made in the gut to fight dangerous bacteria and viruses that enter the digestive system, but this idea is still speculative, says Rudd.
The team’s findings echo recent research in baboons showing that a protein called alpha-synuclein that clumps together in the brains of people with Parkinson’s disease can also spread from the gut to the brain.
Regards,
Hotblack.
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