2023-10-31 20:19:35
MONTREAL — Researchers have succeeded in reproducing the cognitive symptoms of Alzheimer’s disease in healthy mice by grafting the intestinal microbiota of human patients suffering from the disease.
These results, write the researchers, “reveal that the symptoms of Alzheimer’s disease can be transferred to a healthy young organism via the intestinal microbiota, which confirms the causal role of the intestinal microbiota in Alzheimer’s disease” .
“Alzheimer’s disease is a complex and multifactorial neurodegenerative disease,” recalled Doctor Charles Ramassamy, holder of the Louise & André Charron Chair in Alzheimer’s disease at the National Institute of Scientific Research.
“Recent studies have shown that there are several specific alterations in the composition of the intestinal microbiota in patients with Alzheimer’s disease.”
On the other hand, he added, we do not know if these alterations are the origin of the disease, or if they arise rather from the usually advanced age of the patient or from treatments (such as taking antibiotics). that he may have received and which can modify the composition of the intestinal microbiota.
In the new study, transplanting microbiota from Alzheimer’s patients into mice caused memory problems, including problems with long-term spatial memory and difficulty remembering events, people or objects previously encountered.
These memory disorders depend on the development of new neurons in the brain. The researchers observed, in the transplanted mice, a reduction in the number of neuronal stem cells and their survival time, “which supports our behavioral observations,” they write. The neural stem cells created also seemed to have connection problems.
The authors of the study, said Dr. Ramassamy, “observed with interest that there are alterations in the intestinal epithelium of the rats that receive the transplant.”
“And even more interestingly, there is an alteration in the activity of the hippocampus, which is a region in the brain that is very important, that is involved in learning and in memory, and that is altered in Alzheimer’s disease,” he said.
All this, he continues, “really shows that the microbiota of patients is at the origin of these problems in the brain (and) the hippocampus”.
Researchers are now raising the hypothesis that it may be possible to obtain “therapeutic gains” by acting on the intestinal microbiota to influence the creation of healthy neurons.
It may indeed be possible to delay the onset of the disease in people in whom warning signs are detected “by playing on specific populations of bacteria that may or may not be beneficial,” said Dr. Ramassamy.
“It demonstrates once once more the double communication that exists between the brain and the intestine,” he added. This is a new indication which supports the role of the intestinal microbiota on the brain.
The findings of this study were published by the medical journal Brain.
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