Regional disparities in cognitive life expectancy: The role of birth and current residence in the United States.

Regional disparities in cognitive impairment are well-documented, but the combined impact of birth and current residence remains unclear. Prior studies examine geographic patterns, yet none estimate years spent in different cognitive states-key for understanding long-term health and policy implications. Using data from the 1998-2020 Health and Retirement Study (105,491 observations from 19,213 individuals), we employ a Bayesian multistate life table approach to estimate cognitively healthy and impaired life expectancies at age 50 across different combinations of birth and current regions. Our findings show that birth region plays a stronger role in cognitive impairment risk than current residence. At age 50, Southern-born individuals, regardless of where they live later, have fewer years without cognitive impairment (Men: 20.5-21.5; Women: 24.8-25.4) and more years with dementia (Men: 2.3-2.5; Women: 3.0-3.1) than those born elsewhere. Those both born and living in the South have the shortest cognitively healthy life expectancy. Regional differences based on current residence alone are minimal and only evident when considered alongside birthplace. Beyond the Southern birth disadvantage, we also identify a Western birth disadvantage, particularly in life expectancy with dementia and, for women, a higher percentage of life spent with cognitive impairment but not dementia. This suggests that Western-born individuals, especially women, may experience prolonged cognitive decline even if they avoid full-blown dementia. These findings provide new evidence of the lasting impact of early-life geographic exposures on cognitive impairment risk, underscoring that growing up in certain regions, particularly the South and, in some respects, the West, can shape cognitive health trajectories decades later.