Plant‐based dietary patterns and cognitive function in U.S. adults: A prospective evaluation

Abstract Background A plant‐based dietary patterns focus on foods primarily from plant sources. However, not all plant‐based foods are necessarily beneficial for health. We aim to examine the relationship between plant‐based diet quality and cognitive function. Method Analyses were conducted among 701 participants from the Memory and Aging Project. Food Frequency Questionnaires (FFQ) were incorporated into the studies in 2004 and collected annually thereafter. Individuals with mild cognitive impairment, missing food‐frequency questionnaire (FFQ) at baseline, extreme BMI, and less than two cognitive assessments during 10 years of follow‐up were excluded for these analyses. Plant‐based diet quality were assessed by 3 plant‐based diet indices (score range, 18‐90) including 1) an overall plant‐based diet index (PDI) by assigning positive scores to all plant foods and reverse scores to animal foods; 2) a healthful PDI (hPDI) where positive scores were given to only healthy plant foods, less‐healthy plant foods and animal foods received reverse scores; 3) an unhealthful PDI (uPDI), where less‐healthy plant foods received positive scores and animal and healthy plant foods received reverse scores. Our primary outcome was composite global cognition z score. We used liner mixed model examining the association between PDI (as a continuous and categorical) and cognitive decline. Result Higher hPDI was associated with a better cognitive functioning during follow‐up. Compared to individuals in the first tertile of hPDI, individuals in the third tertile had slower cognitive decline by 0.03 units per year (β = 0.03, p=0.017). Similarly, when we evaluated the hPDI as continuous variable, each10‐points increase in hPDI was associated with 0.01 units/year slower cognitive decline. In contrast, higher adherence to uPDI was associated with faster cognitive decline. Individuals in the third tertile of uPDI had a faster decline by 0.04 unites per year (β = 0.04 , p=0.017). Every 10‐point increase in uPDI was associated with a 0.01 unit per year faster cognitive decline. Conclusion Higher intake of a plant‐based diet index rich in healthier plant foods was associated with slower cognitive decline. This supports current recommendations to shift to diets rich in healthy plant foods, with lower intake of less healthy plant and animal foods.