A blood-based nutritional risk index explains cognitive enhancement and decline in the multidomain Alzheimer prevention trial

Introduction: Multinutrient approaches may produce more robust effects on brain health through interactive qualities. We hypothesized that a blood-based nutritional risk index (NRI) including three biomarkers of diet quality can explain cognitive trajectories in the multidomain Alzheimer prevention trial (MAPT) over 3-years. Methods: The NRI included erythrocyte n-3 polyunsaturated fatty acids (n-3 PUFA 22:6n-3 and 20:5n-3), serum 25-hydroxyvitamin D, and plasma homocysteine. The NRI scores reflect the number of nutritional risk factors (0-3). The primary outcome in MAPT was a cognitive composite Z score within each participant that was fit with linear mixed-effects models. Results: Eighty percent had at lease one nutritional risk factor for cognitive decline (NRI >= 1: 573 of 712). Participants presenting without nutritional risk factors (NRI=0) exhibited cognitive enhancement (beta = 0.03 standard units [SU]/y), whereas each NRI point increase corresponded to an incremental acceleration in rates of cognitive decline (NRI-1: beta = -0.04 SU/y, P = .03; NRI-2: beta = -0.08 SU/y, P < .0001; and NRI-3: beta = -0.11 SU/y, P = .0008). Discussion: Identifying and addressing these well-established nutritional risk factors may reduce age-related cognitive decline in older adults; an observation that warrants further study. (C) 2019 The Authors. Published by Elsevier Inc.