46 Cognitive Reserve and Gait Speed are Associated with Cognitive Performance in Black/African American Older Adults

Abstract

Objective:

Cognitive reserve and health-related fitness are associated with favorable cognitive aging, but Black/African American older adults are underrepresented in extant research. Our objective was to explore the relative contributions and predictive value of cognitive reserve and health-related fitness metrics on cognitive performance at baseline and cognitive status at a 4-year follow up in a large sample of Black/African American older adults.

Participants and Methods:

Participants aged 65 years and older from the Health and Retirement Study (HRS) who identified as Black/African American and completed baseline and follow-up interviews (including physical, health, and cognitive assessments) were included in the study. The final sample included 321 Black/African American older adults (mean age = 72.8; sd = 4.8; mean years of education = 12.3; sd = 2.9; mean body mass index (BMI) = 29.1; sd = 5.2; 60.4% identified as female). A cross-sectional analysis of relative importance – a measure of partitioned variance controlling for collinearity and model order – was first used to explore predictor variables and inform the hierarchical model order. Next, hierarchical multiple regression was used to examine cross-sectional relationships between cognitive reserve (years of education), health-related fitness variables (grip strength, lung capacity, gait speed, BMI), and global cognition. Multiple logistic regression was used to examine prospective relationships between predictors and longitudinal cognitive status (maintainers versus decliners). Control variables in all models included age, gender identity, and a chronic disease index score.

Results:

Cross-sectional relative importance analyses identified years of education and gait speed as important predictors of global cognition. The cross-sectional hierarchical regression model explained 33% of variance in baseline global cognition. Education was the strongest predictor of cognitive performance (β = 0.48, p < 0.001). Holding all other variables constant, gait speed was significantly associated with baseline cognitive performance and accounted for a significant additional amount of explained variance (ΔR = 0.01, p = 0.032). In a prospective analysis dividing the sample into cognitive maintainers and decliners, a single additional year of formal education increased chances of being classified as a cognitive maintainer (OR = 1.30, 95% CI = 1.17-1.45). There were no significant relationships between rate of change in health-related fitness and rate of change in cognition.

Conclusions:

Education, a proxy for cognitive reserve, was a robust predictor of global cognition at baseline and was associated with increased odds of maintaining cognitive ability at 4-year follow up in Black/African American older adults. Of the physical performance metrics, gait speed was associated with cognitive performance at baseline. The lack of observed association between other fitness variables and cognition may be attributable to the brief assessment procedures implemented in this large-scale study.