Preliminary Evidence for an Association Between the Composition of the Gut Microbiome and Cognitive Function in Neurologically Healthy Older Adults

Objectives: Dysbiosis of the gut microbiome is implicated in numerous human health conditions. Animal studies have linked microbiome disruption to changes in cognitive functioning, although no study has examined this possibility in neurologically healthy older adults. Methods: Participants were 43 community-dwelling older adults (50–85 years) that completed a brief cognitive test battery and provided stool samples for gut microbiome sequencing. Participants performing≥1 SD below normative performance on two or more tests were compared to persons with one or fewer impaired scores. Results: Mann Whitney U tests revealed different distributions of Bacteroidetes (p=.01), Firmicutes (p=.02), Proteobacteria (p=.04), and Verrucomicrobia (p=.003) between Intact and Impaired groups. These phyla were significantly correlated with cognitive test performances, particularly Verrucomicrobia and attention/executive function measures. Conclusions: The current findings suggest that composition of the gut microbiome is associated with cognitive test performance in neurologically healthy older adults. Future studies are needed to confirm these findings and explore possible mechanisms. (JINS, 2017, 23, 700–705)