Racial and Geographic Disparities in Risk and Survival of Alzheimer's Disease and Related Dementias

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Abstract There exists a limited number of studies that assess health disparities in Alzheimer’s Disease (AD) and even fewer for non-AD dementias. Insight from existing literature and our preliminary studies suggest that the most essential health disparities in Alzheimer’s disease (AD) and related dementias (ADRD) are related to race/ethnicity effects in AD risk and strong geographic gradient in mortality from AD. Our preliminary studies showed significant gaps between incidence rates for different race groups and mortality rates between East and West coast populations. In addition less significant disparities related to effects in rural/urban subpopulations and differences in survival from AD/ADRD were also identified. Detailed epidemiologic descriptions of these disparities, especially incorporating subgroups of AD-related dementias (ADRD), are lacking and the role of behavioral factors, comorbidity, time-dependent cognitive trajectories, and genetic effects in the developments of AD/ADRD are not sufficiently evaluated. Thus, there is a critical need to quantitatively describe the persistent disparities in the AD/ADRD outcomes and clarify the role of the multiple contributing factors. Our preliminary studies proved the ability to extract high-quality measures of the factors to be studied from the three datasets to be used in this study: 5%-Medicare, HRS-Medicare, and SEER-Medicare as well as Multiple Cause of Death database. Research in the project will be focused on i) re-evaluation of the disparities by calculating them with better accuracy and addressing limitations of our preliminary analyses, ii) multiple analyses designed to explain these disparities by analyzing the effects of potential mediators, iii) incorporating recent advanced methodological approaches such as a new partitioning approach for the decomposition of an overall trend into its causal components for analyses of these disparities in high volume data, and iv) incorporating new concepts for the explanation of these disparities, such as the contribution of over/underdiagnoses, heterogeneity in disease severity at time of diagnosis, analyses of patterns of conditions related to AD and ADRD, and the contribution of AD resilience to these disparities. Four Specific Aims planned in this study will deal with i) epidemiology of AD/ADRD, ii) behavior factors and comorbidity, iii) cognitive status and the effects of diagnosis severity and over/under diagnosis, and iv) genetic effects and cognitive resilience. The completion of these Aims will results not only in robust estimates of the disparities in AD/ADRD outcomes in diverse populations, but also, ultimately results in improvements in public health that can be achieved through reducing the identified disparities in AD/ADRD using targeted information based on the in-depth analyses conducted in this project. The expected outcome will be detailed disease-specific information presented in a quantitative form that provides the contribution of each studied factor to race/income-related health disparities in U.S. older adults. We will uncover the barriers in health-care provision that can be further used for improving primary, secondary, and tertiary prevention in the U.S. resulting, in their turn, in improved survival and higher life span.