WALNUTS, THE GUT-BRAIN AXIS AND COGNITIVE FUNCTION

OBJECTIVE 1: To measure the impact of walnuts on postprandial cognitive function in adults who report subjective cognitive complaints.Primary Hypothesis 1A: The primary hypothesis of this proposal, and on which power was calculated, is a walnut meal will support higher postprandial cognitive function compared to a meal without walnuts. Predetermined covariates, including pre-meal cognitive scores, age, sex, obesity, and education level, will be adjusted to approve accuracy and precision in evaluating the influence of walnuts on postprandial cognitive function. A mixed model will be used for data analysis on intent-to-treat basis. Hypothesis 1B: Our secondary hypothesis is that 7 days of consuming a walnut snack (56 g/d) will result in better baseline (under fasting condition) cognitive function than baseline cognitive performance after 7 days of consuming a control snack. Hypothesis 1C: Using a biomarker of walnut intake, e.g., sum of ALA + LA [53], a higher magnitude of change of plasma sum of ALA+LA is correlated to better cognitive function (baseline test.)OBJECTIVE 2: To assess the effect of daily walnut consumption on the gut-brain axis in relationship to cognitive function.Hypothesis 2A: Daily walnut consumption (56 g walnuts per day) for seven days will reduce endotoxemia, a marker of intestinal permeability; and Hypothesis 2B: Seven days of walnut consumption will increase b-diversity and alter microbiota taxa in the intestinal tract. Hypothesis 2C: The changes of endotoxemia and microbiota composition in response to walnut supplementation will track with preservation of post-prandial cognitive function.