[Association between the Gut Microbiome and Cognitive Function].

Dysregulation of the gut microbiome is associated with several life-threatening conditions, and might therefore represent a useful target for the prevention of dementia. However, the relationship between the gut microbiome and dementia has not yet been fully elucidated. Here, we recruited outpatients visiting our memory clinic to participate in this study. Information for patient demographics, various risk factors, and daily activities was collected, and cognitive function was assessed using neuropsychological tests and magnetic resonance imaging scans. Fecal samples were obtained, and the gut microbiome was assessed by terminal restriction fragment length polymorphism (T-RFLP) analysis, one of the most well-established and reliable 16S ribosomal RNA-based methods for classifying gut microbiota. Multivariable logistic regression models were used to identify factors independently associated with dementia and mild cognitive impairment. Graphical modelling was used to illustrate mutual associations. We analyzed 128 eligible patients (female: 59%, mean age: 74.2±8.7 years, mean Mini Mental State Examination score 24). Multivariable analyses showed that enterotype I and enterotype III bacteria were strongly associated with dementia, independent of traditional dementia biomarkers. Further studies investigating metabolites of gut microbes are needed to determine the mechanism underlying this association.