The overall aim of this longitudinal study is to identify new, modifiable mechanisms of racial/ethnic disparities in Alzheimer's disease (AD) among a multi-ethnic cohort of approximately 2,000 older adults. The incidence of AD is higher for African Americans and Hispanics, compared to non-Hispanic Whites, even after controlling for the ?usual suspects? in disparities research: traditional socioeconomic indicators and vascular health. Persistent and unexplained disparities suggest two possibilities that have not been well-examined: (1) known AD risk factors exhibit differential impact across race/ethnicity and/or (2) yet unmeasured factors increase AD risk for minorities. Our research team has identified multiple factors that have stronger cognitive impact among older African Americans or Hispanics, including depressive symptoms and MRI markers of brain pathology. These variables, along with poor vascular health and lower education/income, may be less impactful among Whites because membership in a majority group is associated with social-environmental resources that promote resilience. In the current proposal, resilience is conceptualized as better-than-expected outcomes given level of AD risk factors or brain pathology. This study will examine how resources that differ across race/ethnicity in our cohort (e.g., perceived social status, quality of education, and the perception that life outcomes are controllable) promote resilience at multiple points in the AD pathogenic pathway using repeat MRI and cognitive assessments across three time points. Because racial/ethnic minorities face unique stressors (e.g., acculturative stress, racial discrimination), we will also test whether these experiences influence the progression of MRI markers of brain pathology, cognitive decline, and incident AD. Our overarching hypothesis is that AD disparities persist because racial/ethnic minorities have depleted resources to adapt to known AD risk factors and brain pathology and/or unique, yet unmeasured AD risk factors.
Specific aims are to (1) identify risk factors relevant to minority populations and examine whether they predict advancing brain pathology, cognitive decline, and incident AD among African Americans or Hispanics, (2) determine which resources explain racial/ethnic differences in the impact of known AD risk factors on advancing brain pathology (i.e., brain resilience), and (3) determine which resources explain racial/ethnic differences in the impact of advancing brain pathology on cognitive decline and incident AD (i.e., cognitive resilience).
The prevalence of AD and the societal burden associated with AD treatment and care are on the rise because the U.S. population is aging. The proportion of U.S. elders who are African American or Hispanic is also increasing. These groups are at higher risk for AD than similarly aged non-Hispanic Whites, even after traditional socioeconomic indicators and cardiovascular health are taken into account. It is therefore critical to identify other, modifiable factors that reduce AD risk and eliminate racial/ethnic disparities in AD.
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