Nutrition, gUT microbiota, and BRain AgINg (the NutBrain Study): rational, study design, and preliminary data.

Introduction: The NutBrain study aims to explore the association of dietary habits with cognitive function, and their role in modulating the gut microbiota and brain markers as well. Methods: This is an ongoing population-based study of community-dwelling adults aged >65 years in Northern Italy. Participants are screened for cognitive functions, clinical and dietary data are also collected. Suspected cases of Mild Cognitive Impairment (MCI) undergo a neurological examination and brain MRI scanning. Stool and blood samples are collected and processed for the gut microbiota analysis and APOE genotype. For each MCI two controls matched for sex and age, are recruited. Results: To date 429 individuals have completed the screening evaluation (mean age 74.1±6.6 yrs, 59.8% females). Overall, 22% had MCI (60% multiple-domain), 50% were hypertensive, 38.5% hypercholesterolemic, 22% experienced depressive symptoms, and 25% were at risk of malnutrition or malnourished. We preliminarily analysed dietary data in a subsample of 128 participants underwent clinical visit. Compared to controls, MCI (11% had at least one APOE?4 allele) consumed less fruit and vegetables and had lower intake of PUFAs, omega-3 and omega-6, potassium, retinol, vitamin B6, B12, and K (P<0.05). Discussion: The results of this study will help to understand the relationship between nutrition, gut microbiota, and markers of brain aging and to plan lifestyle interventions for both prevention and treatment of neurocognitive aging.