Cognitive Function Influenced by Gut Microorganisms

A recent study has found a link between microorganism composition that are in the gut and cognitive health. It adds to a growing wealth of research into the interactions between the brain and gut microbiome. Researchers are finding a variety of ways microorganisms in the gastrointestinal tract are diverse leading to studies over the past few years.

Earlier studies in animals and small clinical studies have shown changes in cognition could be linked to changes in the gut microbiome. But there has been few studies investigating cognition and gut microbiome in large samples in community settings.

Recently U.S. researchers have analyzed data from a large cross sectional study and found a connection between cognition in middle aged adults and gut microbial composition. Participants were recruited from across the U.S. as part of the CARDIA Study (Coronary Artery Risk Development in Young Adults).

The CARDIA study 30 year follow-up examination took place in 2015-2016 and had 3,358 participants. The participants were given a set of cognitive assessments as a part of the study with 3,124 participants completing at least one of the assessments. Also, 615 participants were recruited into a microbiome sub-study which sent stool samples to a lab for DNA sequencing.

Six cognitive tests were used – Rey-Auditory Verbal Learning Test, Digit Symbol Substitution Test, letter fluency, Stroop Test, Montreal Cognitive Assessment, and category fluency. The results of the tests were collated for a summary score for each participant.

Other factors were accounted for that could influence either the microbiome composition or test scores in the analysis. The factors included education level, demographics, physical activity, smoking status, medications and diet. Data on comorbidities such as diabetes and hypertension was also collected.

607 of the 615 participants had stool samples that were suitable for DNA sequencing. Ten of the participants didn’t have complete data on the cognitive tests so analysis was used for 597 participants.

Participants were aged 48 to 60 with an average age of 55. 45.2% were Black, 44.7% were men and 44.8% were white. The analysis focused on three main areas – within-person diversity, between person diversity and the individual composition of microorganisms in the sample of stools.

Microbial composition was greatly linked with cognitive measures in the between-person differences after adjusting for risk factors. There was a statistically notable interaction by sex and no notable difference within race. Within-person diversity was generally not linked with cognition in the data.

Future work is essential using whole metagenomics sequencing called shotgun. This is a quick method of sequencing of DNA and gives more information in regards to the interactions and metabolic pathways that take place in the microbiome.

Data that is collected over multiple time points is also needed. This might confirm that gut microbial changes can occur before physiological changes.

There is also a need for longitudinal analysis that collects a lot of information on our health behaviors and social environment to see how these factors and the microbiome will influence health. It is possible that different behaviors and exposures could affect a person’s microbes in different ways and would be important for interventions in the future on a personal level.

The hope is that additional evidence could lead to opportunities to reduce cognition decline in later life. There is the potential to adjust the gut microbiota by altering targeted treatments and health behaviors.
But microbiota could eventually be utilized to identify biomarkers that are involved in risk of chronic diseases which will lead to cognition decline.

To view the original scientific study click below:
Association of the Gut Microbiota With Cognitive Function in Midlife