Date of Award

Spring 5-15-2020

Author's School

Graduate School of Arts and Sciences

Author's Department

Public Health

Degree Name

Doctor of Philosophy (PhD)

Degree Type



Although Alzheimer’s disease and dementia is prevalent across all sociodemographic groups, past research has found African Americans have among the highest risk compared to all other racial/ethnic groups. Despite substantial empirical research supporting this disparity, the reasons for these observed racial/ethnic differences in Alzheimer’s disease and dementia risk remain unclear. The central purpose of this study was to examine the influence of lifestyle behaviors on the differential risk for dementia between White and African American older adults. To better understand this relationship, this study included three aims: 1) To determine the influence of lifestyle behaviors (physical activity, smoking, social contacts) on dementia risk among older adults, 2) To determine how lifestyle behaviors mediate the relationship between race/ethnicity and dementia risk among White and African American older adults, and 3) To determine how race/ethnicity moderates the relationship between lifestyle behaviors and dementia risk among White and African American older adults. This study analyzed eight annual waves (2011-2018) of prospective longitudinal data from the National Health and Aging Trends Study (NHATS), a large nationally representative U. S. Medicare beneficiaries age 65 and older. At each wave, physical activity was measured as engagement in vigorous physical activities; smoking was measured as current engagement in cigarette smoking; and social contacts was measured as visiting friends/family not living with them. The dependent variable was number of years to a new dementia diagnosis. Multivariate analyses were conducted using the Cox proportional hazards model with survey sampling weights applied to a national sample of 6,126 community-dwelling older adults dementia-free at baseline. For Aim 1, after controlling for sociodemographics and health, longitudinal engagement in physical activity was shown to significantly decrease dementia risk (hazard ratio [HR]=0. 54, p<. 05). These findings indicate physical activity is a promising modifiable lifestyle behavior to prevent dementia, regardless of race/ethnic group. Future research should explore types of physical activity interventions that are most effective in reducing dementia risk. For Aim 2, African Americans showed a significantly increased dementia risk (HR=1. 40, p<. 05) after controlling for sociodemographics and health, but this differential risk was attenuated and no longer statistically significant after controlling for lifestyle behaviors (HR=1. 37, p=. 06). This suggests that lifestyle behaviors may be an important factor when understanding pathways and reducing dementia disparities among African Americans. For Aim 3, there were no statistically significant interaction effects between race/ethnicity and lifestyle behaviors, indicating that further research is needed to investigate how lifestyle behaviors can be tailored to reduce dementia risk among African Americans.


English (en)

Chair and Committee

Nancy Morrow-Howell

Committee Members

Shenyang Guo, Sojung Park, Darrell Hudson, Denise Head,

Available for download on Saturday, May 08, 2100