Several animal experiments and small clinical studies support a role for the gut microbiota in cognitive functioning. To add further value, a recent study suggests that a healthy, diverse gut microbiome is associated with better cognitive function in middle age. The study findings were published in the JAMA Network Open on February 08, 2022.
Small-scale human studies have shown associations between microbial features and cognition or found significant improvements when comparing controls with persons who have been treated with probiotics to increase commensal microbiota. However, only a few community-based studies have been conducted with large and diverse populations. Therefore, Dr Katie Meyer and her team conducted a study to examine associations of gut microbial composition with measures of cognition in an established population-based study of middle-aged adults.

In this cross-sectional study, the researchers analyzed data from the prospective Coronary Artery Risk Development in Young Adults (CARDIA) cohort in 4 US metropolitan centers between 2015 and 2016. During that examination, participants took a battery of cognitive assessments and 615 also provided a stool sample for a microbiome substudy; of these, 597 had both stool DNA available for sequencing and a complete complement of cognitive tests. The researchers assessed the cognitive status using 6 clinic-administered cognitive tests: Montreal Cognitive Assessment (MoCA), Digit Symbol Substitution Test (DSST), Rey-Auditory Verbal Learning Test (RAVLT), Stroop, category fluency, and letter fluency. They conducted three standard microbial analyses: within-person alpha-diversity between-person beta-diversity and individual taxa. They further assessed the global score measure derived using principal components analysis.
Key findings of the study:
♦ Upon analysis, the researchers found that After fully adjusting for sociodemographic variables, health behaviors, and clinical covariates, the researchers found that three genera were positively associated, while one was negatively associated with cognitive measures.
♦ Positively associated Genera were,
Barnesiella with the first principal component (Beta diversity β, 0.16) and DSST (β, 1.18)
Lachnospiraceae FCS020 group with DSST(β, 2.67)
Akkermansia with DSST (β, 1.28).
♦ Negatively associated genera were Sutterella with MoCA (β, −0.27).
The authors concluded, "In this cross-sectional study, microbial community composition, based on β-diversity, was associated with all cognitive measures in multivariable-adjusted analysis. These data contribute to a growing body of literature suggesting that the gut microbiota may be associated with cognitive ageing, but must be replicated in larger samples and further researched to identify relevant pathways."
For further information:
DOI:10.1001/jamanetworkopen.2021.43941
Keywords: Gut microbiota, Cognitive function, Barnesiella, Akkermansia, Sutterella, Lachnospiraceae FCS020, CARDIA Study, β-diversity, Montreal Cognitive Assessment (MoCA), Digit Symbol Substitution Test (DSST), Rey-Auditory Verbal Learning Test (RAVLT), Stroop, category fluency, letter fluency, JAMA Network Open, Katie Meyer