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According to a study released Wednesday that would eliminate the dead but toxic cells found naturally in the brains of mice designed to mimic Alzheimer's disease, neuronal damage and memory loss associated with this disease could slow down the fight against dementia.
The accumulation in the body of "zombie cells" that can no longer divide but still cause damage to other healthy cells, a process called senescence, is common to all mammals.
Scientists have long known that these dead cells congregate in areas of the brain related to old age diseases ranging from osteoarthritis and atherosclerosis to Parkinson's disease and dementia.
Previous research had also shown that the elimination of senescent cells in aging mice prolonged their healthy lifespan.
But the new results, published in Nature, are the first to demonstrate a causal link with a specific disease, Alzheimer's, said the scientists.
But all the treatments that might emerge from the research are in many years, they warned.
In experiments, a team led by Tyler Bussian of the Mayo Clinic in Rochester, Minnesota, used genetically engineered mice to produce the destructive entanglements of spider-like tau protein that form in neurons. patients with Alzheimer's.
The mice have also been programmed to allow the elimination of "zombie" cells in the same region.
"When the senescent cells were removed, we found that sick animals retained the ability to form memories and eliminated signs of inflammation," said lead author Darren Baker, also of the Mayo Clinic. .
The mice also failed to develop the protein "entanglements" characteristic of Alzheimer's disease and retained a normal brain mass.
Keep zombies at bay
Further investigation revealed that "zombies" belonged to a class of brain and spinal cord cells, called glia, that provide crucial support and isolation to neurons.
"Preventing the buildup of senescent glia can block the cognitive decline and neurodegeneration normally experienced by these mice," said Jay Penney and Li-Huei Tsai, both of MIT, in Nature.
Bussian and his team duplicated the results with pharmaceuticals, suggesting that drugs may one day slow down or block the emergence of Alzheimer's by keeping these zombie cells at bay.
"There has not been a new dementia drug in 15 years, so it's interesting to see the results of this promising study in mice," said James Pickett, research director at the Alzheimer Society. from London.
For Lawrence Rajendran, deputy director of the Institute for Dementia Research at King's College London, the findings "open up new perspectives for the diagnosis and treatment of neurodegenerative diseases, including stroke disease." 39; Alzheimer's. "
Until now, dementia research focused primarily on diseased neurons rather than neighboring cells.
"It is becoming increasingly clear that other brain cells play a determining role," Rajendran added.
Several barriers remain before the breakthrough translates into "safe and effective treatment for people," said Pickett and others.
Older people often have a lot of harmless brain cells that look like dangerous senescent cells that a drug would target, so the molecule should be able to distinguish the two.
Globally, about 7% of people over the age of 65 suffer from Alzheimer 's disease or from a form of dementia, a percentage that reaches 40% above the age of 18. 85 years old.
The number of people affected is expected to triple by 2050 to 152 million, according to the World Health Organization, posing a huge challenge for health systems.
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