BACKGROUND
African American (AA) adults have about twice the risk of developing dementia compared to White adults. However, evidence on dietary modification in preventing cognitive decline from diverse populations focusing on AA adults is minimal.
OBJECTIVES
To evaluate the association between a plant-based diet and the rate of cognitive decline in a population-based sample of AA and White adults.
METHOD
This study consisted of 3337 participants from the Chicago Health and Aging Project (60% AA participants, 64% female). Plant-based diet quality was evaluated by the overall plant-based diet index (PDI), the healthful PDI (hPDI), and the unhealthful PDI (uPDI). Global cognition was assessed using a composite score of four individual tests of cognition. We used mixed models to examine the association of PDI, hPDI, and uPDI and the rate of decline in global cognition, perceptual speed and episodic memory. Models were adjusted for age, sex, presence of ApoE e4 allele, lifestyle factors including education, cognitive activities, smoking status, calorie intake, risk factors of cardiovascular disease (CVD), time, and the interaction term of time with each covariate.
RESULTS
AA and White participants have various dietary patterns. Higher hPDI was associated with a slower rate of decline in global cognition, perceptual speed and episodic memory in AA participants but not White participants. AA study participants in the highest quintile of hPDI had significantly slower rates of global cognitive decline, β = 0.0183 ± 0.0086 (p = 0.032), perceptual speed β = 0.0179 ± 0.0088 (p = 0.04) and episodic memory β=0.0163 ± 0.0118 (p = 0.04) compared to individuals in the lowest quintile of hPDI. There were no associations with either PDI or uPDI and the rate of cognitive decline in either racial group.
CONCLUSION
A healthy plant-based diet was associated with a slower rate of decline in global cognition, perceptual speed, and episodic memory in AA adults.