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According to a new American study, Alzheimer’s disease could find its origin in an evolutionary bad adaptation linked to our diet which involves fructose in our distant ancestors.
A degenerative disease affecting approximately one million people in France, Alzheimer’s disease still has many mysteries, particularly in terms of its causes and the way in which it can be treated. A new study conducted by the University of Colorado Anschutz Medical Campus in the United States, may well give new clues about how this disease appeared in humans. According to the researchers, we should dig into an ancient human instinct to seek food, fueled by the production of fructose in the brain during times of food shortage, in our distant ancestors.
Fructose, a sugar used in foraging by our ancestors
The theory of these researchers is pointed: when the first humans on earth faced a food shortage, a survival reaction requiring concentration, determinism and risk-taking, was put in place, to seek food. Parameters that fructose metabolism can enhance by reducing blood flow to the cerebral cortex and allowing more blood flow around the visual cortex, but still affecting other factors, such as memory. In fact, fructose would have allowed the first men to survive and last over time.
In any case, this is how Dr. Richard Johnson, first author of the study explains it:
“We believe that initially, the fructose-dependent reduction of brain metabolism in these regions was reversible and expected to be beneficial.. But a chronic and persistent reduction in brain metabolism driven by recurrent fructose metabolism leads to progressive brain atrophy and loss of neurons with all the hallmarks of Alzheimer’s disease.”
An irreversible evolutionary remnant?
The evolutionary mechanism driven by fructose would therefore have enabled the human species to survive. But would have remained inscribed in our functioning (hence our interest in sweet and fatty foods) at the origin of an overproduction of fructose, which, in the long term, could cause cerebral inflammation, even dementia. A theory verified in animals.
“A study found that if you keep lab rats on fructose long enough, they get a buildup of tau and beta-amyloid proteins in the brain, the same proteins seen in Alzheimer’s disease.”, said Dr. Johnson. Fructose-fed animals would also observe memory and orientation problems. According to the author, high levels of fructose are also present in the brains of people with Alzheimer’s disease. A last discovery which could, why not, lead to new recommendations?
“Although further studies are needed on the role of fructose metabolism and its metabolite, uric acid, in Alzheimer’s disease, we suggest that dietary and pharmacological trials aimed at reducing exposure to fructose or to block fructose metabolism be performed to determine if there is any potential benefit in the prevention, management or treatment of this disease” concludes the study.