Just like our taste buds and brain work together to identify a delicious meal, it turns out that our gut and brain are also closely connected as we age. Recent research has discovered that the trillions of microbes living in our gut, collectively known as the gut microbiome, play a crucial role in maintaining brain health during aging. Think of it like a dynamic duo, with the gut microbiome acting as the sidekick supporting our aging brain. Factors such as genetics, obesity, calcium intake, vegetable consumption, and even the types of microorganisms residing in our gut can influence this relationship. By investigating the gut-brain connection in a group of older adults, researchers found that individuals with specific genetic variants showed distinct compositions of gut microbes. Those with pro-inflammatory bacteria had higher BMI and diabetes, while those with anti-inflammatory bacteria had diets rich in calcium and vegetables. Interestingly, certain gut microbes were associated with different regions of the brain responsible for relaying information and processing emotions. This exciting research opens up possibilities for targeted interventions such as specific prebiotics, probiotics, or dietary changes to support healthy aging brains. So why not dig deeper and explore the fascinating world of the gut-brain connection?

IntroductionAdvanced age is a significant factor in changes to brain physiology and cognitive functions. Recent research has highlighted the critical role of the gut microbiome in modulating brain functions during aging, which can be influenced by various factors such as apolipoprotein E (APOE) genetic variance, body mass index (BMI), diabetes, and dietary intake. However, the associations between the gut microbiome and these factors, as well as brain structural, vascular, and metabolic imaging markers, have not been well explored.MethodsWe recruited 30 community dwelling older adults between age 55-85 in Kentucky. We collected the medical history from the electronic health record as well as the Dietary Screener Questionnaire. We performed APOE genotyping with an oral swab, gut microbiome analysis using metagenomics sequencing, and brain structural, vascular, and metabolic imaging using MRI.ResultsIndividuals with APOE e2 and APOE e4 genotypes had distinct microbiota composition, and higher level of pro-inflammatory microbiota were associated higher BMI and diabetes. In contrast, calcium- and vegetable-rich diets were associated with microbiota that produced short chain fatty acids leading to an anti-inflammatory state. We also found that important gut microbial butyrate producers were correlated with the volume of the thalamus and corpus callosum, which are regions of the brain responsible for relaying and processing information. Additionally, putative proinflammatory species were negatively correlated with GABA production, an inhibitory neurotransmitter. Furthermore, we observed that the relative abundance of bacteria from the family Eggerthellaceae, equol producers, was correlated with white matter integrity in tracts connecting the brain regions related to language, memory, and learning.DiscussionThese findings highlight the importance of gut microbiome association with brain health in aging population and could have important implications aimed at optimizing healthy brain aging through precision prebiotic, probiotic or dietary interventions.

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