In an earlier paper*, the scientists found that supplementation with Lacticaseibacillus rhamnosus GG (LGG – formerly known as Lactobacillus rhamnosus GG) led to improvements in cognitive performance in middle-aged and older adults with cognitive impairment.
Further analysis of data from the same randomized clinical trial revealed that there is also a correlation between specific members of the gut microbiota with cognitive performance in these people.
Specifically, Prevotella ruminicola, Bacteroides thetaiotaomicron, and Bacteroides xylanisolvens were identified as taxa that correlated with mild cognitive impairment (MCI), and these therefore could be targets for modulation by pre, pro, or synbiotics to slow the progression of cognitive impairment.
“Contrarily to most studies, which reported on the microbiome composition of MCI patients compared to other forms of cognitive dysfunction like AD [Alzheimer’s Disease], we compared MCI to healthy individuals aiming to provide information that could help in the early detection of cognitive aging,” wrote scientists from North Carolina State University, King Saud University (Saudi Arabia), and Kent State University in Clinical Nutrition.
The original randomized clinical trial included 169 community-dwelling middle-aged and older people, aged between 52 and 75. The volunteers were randomly assigned to receive either probiotic (Culturelle, with 10 billion CFUs LGG plus 200 mg of inulin) or placebo for three months.
The researchers further divided the participants based on cognitive status (intact or impaired cognition) and microbiome analysis performed at the start of the study and post supplementation.
“The current study is one of few randomized clinical trials (RCT) in the USA that investigated the microbiome composition associated with MCI compared to their cognitively normal counterparts in healthy individuals using 16S rRNA amplicon and WGS [whole genome shotgun] sequencing,” explained the researcher.
The results showed that Prevotella was significantly more prevalent in people with MCI compared to cognitively intact subjects.
In addition, the researchers noted that there was a correlation between the relative abundance of Prevotella and Dehalobacterium with an improved cognitive score in response to LGG supplementation in the MCI group.
“This study contributes to the understanding of the gut microbiota role on brain aging in the elderly population,” wrote the researchers. “Taken together, our results indicate that LGG had a marginal impact on overall microbiota composition and points to a specific response based on the hosts initial cognitive status.
“Should findings be replicated, these taxa could be used as key early indicators of MCI and manipulated by probiotics, prebiotics, and symbiotics to promote successful cognitive aging.”
Source: Clinical Nutrition
Volume 41, Issue 11, Pages 2565-2576, doi: 10.1016/j.clnu.2022.09.012
“The gut microbiome, mild cognitive impairment, and probiotics: A randomized clinical trial in middle-aged and older adults”
Authors: M.R. Aljumaah et al.
* Sanborn et al. Neuropsychiatric Dis Treat, 16 (2020), p. 2765