These Are the US States, Counties With Rising Alzheimer Disease Prevalence

State-specific prevalence of Alzheimer disease (AD) dementia is found to be highest in the east and southeast regions of the United States, with higher prevalence in states with a larger population aged 65 and older, according to study findings published in the journal Alzheimers & Dementia.

AD and related dementia poses a significant economic burden worldwide, with financial costs of care in the US estimated to be at 321 billion in 2022. As providing state-specific prevalence can assist with budget planning and public health programs, researchers aimed to estimate the prevalence and number of people living with AD dementia in each of the 50 US states.

Researchers utilized a population-based study, termed CHAP (Chicago Health and Aging Project), which evaluated the risk factors for AD dementia in the general population. Residents aged 65 and older from a defined community in the south side of Chicago were included in the study. The researchers obtained demographic information via self- or interviewer-administered questionnaires and evaluated cognitive function with neuropsychological tests for 10,802 enrolled individuals. Person-specific likelihood of dementia was obtained, ranging from 0 to 1, with 1 indicating the highest chance of dementia.

Results from CHAP were coupled with the 2020 bridged-race population estimates, which estimated the population of US residents, categorized by race and ethnicity. Data on residents aged 65 and older were used, to align with the CHAP population.

The researchers formulated a multi-step approached to estimate AD prevalence in the US. Firstly, quasibinomial regression models used person-specific likelihood scores obtained from CHAP as a dependent variable to obtain regression coefficients. Regression coefficients obtained were multiplied by population estimates at the county-level from NCHS data, stratified combinations of age, group, sex and race/ethnicity.

Resultant prevalence in each county was multiplied by the number of people with AD dementia in each county, and state-specific counties were summated to estimate the respective prevalence of AD by state.

The demographic characteristics of AD dementia in the US found women comprised 61% of the population, and Black individuals 63%. An exponential increase in risk for AD was associated with age, with individuals aged 80-84 and 85 and older having the highest risk (odds ratio [OR], 6.05 [95% CI, 5.59-6.55]), and 14.8 [95% CI, 13.6-16.0]), respectively. Black and Hispanic individuals were at a higher risk for AD, when compared with White individuals (OR, 2.50 [95% CI, 2.37-2.63] and 1.73 [95% CI, 1.40-2.13]), respectively.

Prevalence of AD dementia in the US varied by geographic location, with the east and southeastern regions in the US having the highest prevalence.

• Maryland (12.9%)
• New York (12.7%)
• Mississippi (12.5%)
• Florida (12.5%)

California, Florida and Texas were found to be the top 3 states with the highest number of people with AD dementia.

Counties with the highest prevalence of at-risk demographics (aged >65 years, Black and Hispanic ethnicity) were associated with the highest prevalence of AD dementia.

• Miami-Date County, Florida (16.6%)
• Baltimore City, Maryland (16.6%)
• Bronx County, New York (16.6%)

The lack of additional risk factors, such as cardiovascular risk factors (diabetes, hypertension), as well as lifestyle factors (diet, cognitive activity), that were excluded in the study were cited as possible limitations. Additionally, using a single population-based study for effect estimates of demographic factors on dementia risk may have limited the generalizability of the study.

The researchers concluded, “Our county-specific estimates on the prevalence and number of people with AD dementia could be helpful to public health officials to plan better the budget for caring for people with AD dementia.”