2023-06-14 18:26:23
Identifying signs that precede the onset of Alzheimer’s symptoms by two decades
The results of a recent study, published (Wednesday) in the journal “Science Translation Medicine”, showed that people in the first stage of Alzheimer’s disease – when changes begin to occur in the brain and before the symptoms of the disease appear – harbor a variety of bacteria in their intestines that differ from those in the intestines of healthy people. .
During this early stage of Alzheimer’s, people with clumps of amyloid-beta and tau proteins build up in their brains, a stage that can last two decades or more, yet patients show no signs of neurodegeneration or cognitive decline. No one has ever looked at the gut microbiome in the pre-symptomatic stage, according to the findings of the study conducted by researchers at Washington University School of Medicine in St. Louis.
“A change in the gut microbiome could be a readout of pathological changes in the brain,” study co-author Gautam Dantas, professor of genomic medicine and an expert in the gut microbiome at the university, said in a press release issued Wednesday.
He added, “The other alternative is that the gut microbiome may be a contributor to Alzheimer’s disease, in which case altering it with probiotics (a beneficial diet) or stool transfusions (with the beneficial bacteria it carries) may help alter the course of the disease.”
The results open up the possibility of using gut bacteria analysis to identify people most at risk of developing Alzheimer’s disease very early on, and thus design preventive therapies to change the microbiome to stave off the risk of developing the disease, which is the most prominent feature of dementia and cognitive decline.
“With the onset of cognitive symptoms, there are critical and often irreversible changes,” said Bo M. Anis, a professor of neurology at the university, and a co-researcher of the study, explaining that: “If you can diagnose a patient early in the disease, this will be the time.” optimal for effective treatment intervention.
The researchers evaluated the participants, all of whom were cognitively normal. Participants were given stool, blood, and cerebrospinal fluid samples, as well as food lists; They also underwent positron emission tomography and magnetic resonance imaging (MRI) scans of the brain.
To distinguish the participants at an early stage of the disease from the healthy ones, the researchers analyzed signs of accumulation of the proteins amyloid-beta and tau. Of the 164 participants, nearly a third (49) had early signs of the disease.
The analysis revealed that early in life, people with Alzheimer’s developed gut bacteria that were significantly different from their healthy counterparts, both in terms of the types of bacteria and the biological processes in which they were involved. The study’s authors say that these differences could be used for early detection of Alzheimer’s disease.
For his part, Dr. Walid Mahmoud Al-Sharoud, Professor of Microbial Physiology and Food Safety at Mansoura University in Egypt, said in statements to Asharq Al-Awsat: “The results show a correlation between the quality of gut microbes and the early stages of Alzheimer’s disease, in which mental disorders do not appear, but rather occur. Changes in the level of amyloid and tau proteins in brain cells and tissues, which is the stage that follows the occurrence of mental changes associated with Alzheimer’s disease over a period of up to twenty years.
According to the study, these differences are related to the levels of amyloid and tau proteins, which rise before cognitive symptoms appear, but they are not associated with neurodegeneration, whose symptoms also begin to appear with time.
“The beauty of using the gut microbiome as a screening tool is its simplicity and ease of use,” Anis says, explaining that: “People may one day be able to provide a stool sample and find out if they are at increased risk of developing Alzheimer’s.”
Al-Sharoud believes, “The results of the study are interesting and confirm the relationship between the gut microbes and human health.”
Looking ahead, the researchers launched another five-year follow-up study aimed at finding out whether differences in the gut microbiome are a cause or consequence of the brain changes seen in early-onset Alzheimer’s disease.
“If there is a causal link, it is likely to be an inflammatory link,” Dantas explains, noting that “bacteria are amazing chemical factories, and some of their metabolites affect inflammation in the gut, and may reach the bloodstream, where they can affect the body’s immunity.” , stressing that if it turns out that there is a causal relationship, we can start to think about whether boosting ‘good’ bacteria or getting rid of ‘bad’ bacteria could slow or even stop the progression of Alzheimer’s symptoms.
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