Changes in Body Mass Index Are Related to Faster Cognitive Decline Among African American Older Adults.

Background/objectives: The purpose of this study was to: (1) examine relationships between body mass index (BMI) stability and cognitive decline in older African Americans; and (2) investigate differences in the relationships between women and men.
Design: The present study is a secondary data analysis of the Minority Aging Research Study, which is a longitudinal, cohort study of risk factors for cognitive decline and Alzheimer's disease among older African Americans living in the Chicago, IL, area. The study entails annual clinical evaluations, including measures of 19 neuropsychological tests that represent five cognitive domains, including episodic, semantic, and working memory, perceptual speed, and visuospatial ability.
Participants: Participants (n = 671; mean age = 73.5 years; standard deviation = 6.2 years) were included in the present analysis if they were dementia free at baseline and completed at least two clinical evaluations, on average 1 year apart, that included valid cognitive and BMI assessments.
Results: Mixed-effects models showed higher baseline BMI was related to slower global cognitive decline, whereas changes in BMI (instability) were related to faster global cognitive decline. These effects were the same for four of five cognitive domains and remained after controlling for various health characteristics. However, women and men did not differ in any of the relationships.
Conclusion: Higher BMI is related to slower cognitive decline in older African Americans, but greater BMI instability is related to faster decline. Stability of BMI should be considered in the cognitive aging of African Americans.
(© 2020 The American Geriatrics Society.)