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 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 ( = 0.03 standard units [SU]/y), whereas each NRI point increase corresponded to an incremental acceleration in rates of cognitive decline (NRI-1:  = -0.04 SU/y,  = .03; NRI-2:  = -0.08 SU/y,  < .0001; and NRI-3:  = -0.11 SU/y,  = .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.