Why Is ADRD Concentrated in the South? Historical Demographic Trajectories and Life-Course Exposure

Alzheimer’s disease and related dementias (ADRD) are more common in some parts of the United States than others, yet the reasons for these geographic differences remain poorly understood. Over the past century, U.S. counties have followed very different demographic and socioeconomic trajectories. Some experienced population growth, rising educational attainment, and economic development, while others faced population loss, population aging, persistent poverty, and economic decline. These long-term patterns may shape the resources and opportunities available to residents and, in turn, influence dementia risk later in life. This project will use Census, American Community Survey, and Medicare data to identify groups of counties with similar demographic and socioeconomic trajectories from 1900 to 2020 and examine whether these county types differ in contemporary ADRD prevalence. It will also use residential history data from the Health and Retirement Study to examine where individuals lived during childhood and adulthood and whether the timing and duration of exposure to different place environments are associated with cognitive health later in life.