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Alzheimer’s disease is a neurodegenerative disorder still poorly understood by scientists. But studies are continuing and their recent conclusions tend to show an implication of the intestine in the disease.
Several studies conducted by European and British scientists have sought to prove a link between the gut microbiome and Alzheimer’s disease. Their findings, not all of which have yet been peer-reviewed, were nevertheless presented at the conference Alzheimer’s Research UK 2022held earlier this month.
Several studies related to the intestine
Three studies have investigated a link between Alzheimer’s and gut health.
- The first studied the bacteria of the intestine by comparing this microbiome between people affected by the disease and a control group. She notices a big difference in composition between the two;
- The second focused on rodents that had undergone a faecal transplant from patients with Alzheimer’s. Once grafted, the animals performed poorly on the memory tests to which they were subjected;
- Finally, the third study showed that brain stem cells treated with blood from people with brain disorders were then no longer able to develop new nerve cells.
The role of the intestine in Alzheimer’s disease?
Scientists already know the role of inflammation in Alzheimer’s disease, as it notably affects cerebral blood circulation. They now increasingly suspect the influence of intestinal bacteria to be the cause of this inflammation.
Dr Edina Silajdžić from King’s College London worked on the first study. She analyzed blood samples from 68 patients with Alzheimer’s disease and compared them to a similar number of people without the disorder, revealing a “distinct composition of intestinal bacteria” and more inflammation in people with Alzheimer’s disease.
According to her, “most people are surprised that their gut bacteria can affect their brain health. Our gut bacteria can influence the level of inflammation in our body, and we know that inflammation is a key factor in Alzheimer’s disease.”.
The intestine, a lead for a new treatment?
There is currently no treatment to cure Alzheimer’s disease. The only molecule available is aducanumab, an immunotherapy that reduces brain damage associated with the disease. If the gut track is confirmed, this could represent a major step forward, as Professor Yvonne Nolan of University College Cork points out. If this link is confirmed, he says, the gut is a potentially different route of treatment, which could be “easier to reach”, through drugs or changes in diet.
Take care of your lifestyle, while waiting
Pending further studies and solid scientific results, Dr. Susan Kohlhaas, director of research at Alzheimer’s Research UK, recalls the principles of Alzheimer’s disease prevention. “The composition of our gut microbiota is one of many potential dementia risk factors that we can influence by leading a healthy lifestyle. To maintain a healthy brain as we age, the current best evidence suggests that we should stay physically fit, eat a balanced diet, maintain a healthy weight, not smoke, drink only within recommended limits, and control our blood pressure and cholesterol“.