How probiotics could slow cognitive decline

A recent study indicates that probiotics can improve cognitive function and potentially prevent age-related cognitive decline by modulating the gut microbiome. Especially in people with mild cognitive impairment, changes in the composition of the gut microbiome, such as a decrease in the amount of Prevotella bacteria, correlated with improved cognitive scores.

Recent findings point to a key role for the gut in maintaining brain health.

Results from a recent study show that the use of a probiotic can help prevent the decline in memory and thinking that can accompany aging. This discovery may lay the foundation for innovative, non-invasive methods that utilize the gut microbiome to reduce cognitive decline in the elderly.

The researchers discovered that the cognitive scores of study participants who experienced mild cognitive impairment improved after receiving probiotics Lactobacillus rhamnosus GG (LGG) for a period of three months. This improvement in cognitive function was also associated with changes in their gut microbiome.

“The significance of this finding is quite exciting as it means that altering the gut microbiome through probiotics could potentially be a strategy to improve cognitive performance, especially in people with mild cognitive impairment,” said Mashael Aljumaah, a microbiology PhD candidate at the university . of North Carolina at Chapel Hill and North Carolina State University. “This adds a new layer to our understanding of the microbiome’s brain-gut connection and opens new avenues to combat cognitive decline associated with aging.”

Aljumaah, who is also affiliated with King Saud University in Saudi Arabia, recently presented the findings at NUTRITION 2023, the flagship annual meeting of the American Society for Nutrition, held 22-25 July in Boston.

“Many studies focus on severe forms of cognitive diseases such as Alzheimer’s and dementia, but these conditions are more advanced, making them significantly more difficult to reverse or treat,” Aljumaah said. “In contrast, we focused on mild cognitive impairment, which can include problems with memory, language or judgment. Interventions at this stage of cognitive impairment can slow or prevent progression to more severe forms of dementia.”

Graphic abstract. Credit: Mashael Aljumaah, University of North Carolina at Chapel Hill and North Carolina State University

The study involved 169 participants between the ages of 52 and 75, who were divided into two groups depending on whether they had no neurological problems or mild cognitive impairment. Within each group, participants received either LGG probiotics or placebo in a double-blind, randomized clinical trial lasting three months. The researchers chose the LGG probiotic because previous research had shown its potential beneficial effects in animal models.

To examine the study participants’ gut microbiomes, the researchers used 16S rRNA gene sequencing to identify and compare bacteria present in stool samples. They then used whole genome sequencing to gain insight into the functional roles of the identified bacteria.

The analysis revealed that microbes in the genus Prevotella was present in higher relative abundance in participants with mild cognitive impairment than in those without cognitive impairment. This suggests that gut microbiome composition may serve as an early indicator of mild cognitive impairment, providing opportunities for earlier interventions to slow cognitive decline.

For study participants who had mild cognitive impairment and received LGG probiotics Prevotella relative abundance decreased. This change coincided with improved cognitive outcomes, suggesting that cognitive health in older adults could be improved by manipulating the gut microbiota.

“By identifying specific shifts in the gut microbiome associated with mild cognitive impairment, we are exploring a new frontier in preventive strategies in cognitive health,” said Aljumaah. “If these results are replicated in future studies, it suggests the possibility of using gut microbiome-targeted strategies as a new approach to support cognitive health.”

The researchers are now working to understand the specific mechanisms of how microbes suffer Prevotella affect the gut in a way that improves brain health. Specifically, they are investigating how certain molecules produced by these bacteria modulate the functionality of neuroprotective hormones that can cross the blood-brain barrier.

Reference: “The Gut Microbiome, Mild Cognitive Impairment, and Probiotics: a Randomized Clinical Trial in Middle-Aged and Older Adults” by Mashael R. Aljumaah, Andrea M. Azcarate-Peril, Jeffery Roach, John Gunstad, and Urja Bhatia, 24. July 2023, NUTRITION 2023 (abstract; presentation details).