Geographic Patterns of Dementia in the United States: Variation by Place of Residence, Place of Birth, and Subpopulation.

Objectives: The prevalence of dementia varies geographically in the United States. However, the extent to which this variation reflects contemporary place-based experiences versus embodied exposures from earlier in the life course remains unclear, and little is known regarding the intersection of place and subpopulation. This study, therefore, evaluates whether and how risk for assessed dementia varies by place of residence and birth, overall and by race/ethnicity and education.

Methods: We pool data from the 2000 to 2016 waves of the Health and Retirement Study, a nationally representative panel survey of older U.S. adults (n = 96,848 observations). We estimate the standardized prevalence of dementia by Census division of residence and birth. We then fit logistic regression models of dementia on region of residence and birth, adjusting for sociodemographic characteristics, and examine interactions between region and subpopulation.

Results: The standardized prevalence of dementia ranges from 7.1% to 13.6% by division of residence and from 6.6% to 14.7% by division of birth, with rates highest throughout the South and lowest in the Northeast and Midwest. In models accounting for region of residence, region of birth, and sociodemographic covariates, Southern birth remains significantly associated with dementia. Adverse relationships between Southern residence or birth and dementia are generally largest for Black and less-educated older adults. As a result, sociodemographic disparities in predicted probabilities of dementia are largest for those residing or born in the South.

Discussion: The sociospatial patterning of dementia suggests its development is a lifelong process involving cumulated and heterogeneous lived experiences embedded in place.