Khaberni - A new research review, the broadest of its kind to date, has shown that an imbalance in the gut microbiome (gut bacteria) may be a key factor in the development of mild cognitive impairment and Alzheimer's disease, which affects an estimated 6.7 million people in the United States and about 50 million people worldwide, according to a study led by a team from the George Washington University School of Medicine and Health Sciences.
This review, the broadest of its kind, was based on the analysis of 58 human studies published until February 2023, and was distinguished by its complete focus on human studies, which grants its results particular importance, since animal models often do not accurately reflect human biological interactions. The results of this work were published in the journal Alzheimer's Dementia, adding a new perspective to understanding the factors influencing cognitive decline.
A complex network controls neuroinflammation, and researchers have been seeking to understand the biological causes of memory loss and cognitive decline for years. Recent studies indicate that the gut-brain microbiome axis, a key communication system linking the gut, the immune system, and the brain, may play an important role in neuroinflammation and neuronal cell damage, both closely linked to Alzheimer's disease.
Distinct microbial fingerprints in those with cognitive decline The scientific review revealed notable differences in the composition of gut bacteria in individuals with mild cognitive impairment and Alzheimer's disease compared to healthier elderly individuals.
It was found that Alzheimer's patients possess higher levels of certain bacterial groups, particularly Pseudomonadota and Actinomycetota, which are microbial patterns not usually seen in such density in healthy individuals. Researchers also observed a decrease in microbial diversity in some patients, an indicator of a decline in the number of beneficial bacterial species that play a crucial role in maintaining digestive tract balance.
The results also showed that microbial fingerprints differ depending on the stages of cognitive decline, suggesting a gradual change in microbiome composition as the disease progresses. The differences were not limited to composition but also included bacterial functions; changes in the activity of certain biological pathways were observed in Alzheimer's patients, particularly those related to energy production and immune system regulation, which may contribute to a deeper understanding of the relationship between gut health and brain health.
An initial step towards a deeper understanding of the disease's pathway Principal researcher Lee Frem stated that these findings represent an important starting point for understanding how gut health influences neuroinflammation and cognitive decline. She pointed out that most of the available evidence so far relies on observational studies, necessitating clinical trials to determine whether interventions aimed at the microbiome can alter the course of the disease. She noted that such trials are already being conducted in several laboratories around the world.
Although the review does not prove a direct causal relationship, it aligns with increasing evidence suggesting that fiber-rich diets might enhance gut microbiome health, possibly contributing to reduced inflammation and improved long-term brain health.
