State-by-state dementia data now shows a striking concentration of Alzheimer’s cases across the East and Southeast, where age, chronic disease, and demographics intersect.
The number of Americans living with dementia, including Alzheimer’s disease, continues to rise as the population ages, and recent research highlights important geographical differences across the country.
A landmark prevalence study found that states like Maryland, New York, Mississippi, and Florida have some of the highest proportions of adults aged 65 and older living with Alzheimer’s dementia, with rates around or above 12.5 percent. These figures illustrate not just the scale of the challenge but how the impact varies from place to place.
Understanding where dementia rates are highest helps put the issue into perspective for readers and policymakers alike. These patterns reflect underlying demographic factors such as older average age and regional health disparities, and they underline the urgency of targeted prevention efforts and resources. As the U.S. population continues to age and rates climb, identifying state-level hotspots can guide support for research, care programs, and communities that are most affected.
Maryland now tops the list for Alzheimer’s prevalence
Maryland has quietly moved to the front of a national ranking no state wants to lead. A large prevalence modeling analysis published in JAMA Neurology by researchers from the University of Chicago and Rush University Medical Center estimated that 12.9 percent of Maryland residents aged 65 and older are living with Alzheimer’s dementia, the highest share in the country. The estimate draws on national survey data, Medicare records, and clinical cohorts, translating abstract risk into a concrete state-level reality.
The authors link Maryland’s elevated burden to its age structure and demographics. The state has a comparatively large population over age 85 and a substantial Black population, both strongly associated with higher dementia prevalence. County-level estimates place Baltimore City among the highest in the nation, illustrating how dense urban areas with older and historically disadvantaged populations can become Alzheimer’s hotspots within a single state.
New York’s aging and diverse population pushes rates higher
Just behind Maryland sits New York. The same JAMA Neurology analysis estimates that 12.7 percent of New Yorkers aged 65 and older are living with Alzheimer’s dementia. In absolute numbers, the scale is staggering, but the percentages tell a more intimate story of how aging intersects with place.
Bronx County stands out sharply. Researchers estimate roughly 14 percent prevalence there, driven by a concentration of residents over 85 and a population that is about 30 percent Black and 47 percent Hispanic. The authors emphasize that social determinants of health, including neighborhood disadvantage, cardiovascular disease burden, and unequal access to preventive care, compound biological risk and shape these geographic patterns.
Mississippi and Florida emerge as deep South dementia hotbeds
Mississippi and Florida each reach an estimated 12.5 percent prevalence among residents aged 65 and older, placing both states in the national top four. In the JAMA Neurology modeling, the eastern and southeastern United States consistently show the highest Alzheimer’s burden, a pattern long hinted at but now quantified.
The researchers point to overlapping forces. Older age distributions combine with high rates of hypertension, diabetes, and obesity, alongside larger proportions of racial and ethnic groups at elevated risk. Florida also ranks among the top three states for the sheer number of people living with Alzheimer’s dementia, driven by its vast retiree population, with counties such as Miami-Dade emerging as especially heavy burden areas.
California and Illinois combine high prevalence with huge case counts
California and Illinois sit slightly lower by percentage, with prevalence estimates hovering around 12 percent among adults 65 and older. In a smaller state, that figure might feel abstract. In California, it translates into the largest absolute number of Alzheimer’s cases in the nation.
Public health researchers involved in the modeling warn that population size amplifies every decimal point. California, Texas, and Florida together account for millions of current and future cases, concentrating pressure on caregivers, Medicaid programs, and long-term care infrastructure. Even a mid-range prevalence in a mega state becomes a crisis measured in hundreds of thousands of lives.
The Southeast and parts of the West see a sharply higher incidence
Prevalence tells us how many people are living with dementia. Incidence reveals where new cases are emerging. A separate study published in JAMA Neurology by investigators at the University of California, San Francisco, analyzed health records from more than 12.6 million older U.S. veterans. The team found dementia incidence highest in the Southeast and lowest in the Mid Atlantic, even after adjusting for age.
Compared with low-risk Mid Atlantic states, incidence was 25 percent higher in the Southeast, including Kentucky, Tennessee, Alabama, and Mississippi, and 18 percent higher in the South, including Arkansas, Louisiana, New Mexico, Oklahoma, and Texas. Incidence was also about 23 percent higher in the Northwest and Rocky Mountain regions, underscoring that elevated risk is not confined to the traditional Stroke Belt.
County-level maps reveal hidden dementia clusters
One of the most striking contributions of the new work is its county-level lens. By combining cognitive data from the long-running Chicago Health and Aging Project with national demographic surveys, researchers produced the first Alzheimer’s prevalence estimates for all 3,142 U.S. counties.
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The maps reveal clusters that state averages obscure. Among large counties, Miami-Dade, Baltimore City, and Bronx County rank near the top. In Georgia and South Carolina, smaller counties such as Dougherty at 15.3 percent and Orangeburg at 15.2 percent also surface as high burden areas. These pockets highlight rural and small city regions where resources are often thinnest.
Overall dementia prevalence rises even as incidence edges down
At the national level, the picture grows more complex. A Medicare analysis conducted by the Centers for Medicare and Medicaid Services tracked dementia trends from 2015 to 2021 and found that age and sex standardized incidence declined from 3.5 percent to 2.8 percent. Fewer new cases are emerging each year at a given age.
Yet prevalence rose over the same period, from 10.5 percent to 11.8 percent among beneficiaries. More people are living longer with dementia, reflecting improved survival and better management of comorbid conditions. The result is a growing population in need of long-term support, even as prevention gains quietly accumulate.
Researchers warn that the national dementia burden is set to double
Looking forward, the curve bends sharply upward. A recent analysis from NYU Langone Health, published in Nature Medicine, estimates that the lifetime risk of developing dementia after age 55 is now about 42 percent, more than double earlier estimates from decades past. Annual new cases are projected to rise from roughly 500,000 today to about 1 million by 2060.
Data compiled by the Alzheimer’s Association illustrates why geography matters so much. About 5 percent of Americans aged 65 to 74 live with Alzheimer’s dementia, 13.2 percent of those aged 75 to 84, and roughly one-third of those 85 and older. States with older populations inevitably rise to the top of the charts.
Key Takeaway
The new Alzheimer’s mapping makes one truth unmistakable. Dementia in the United States is not evenly distributed. East and Southeastern states now carry the heaviest burden, shaped by age, race, chronic disease, and place.
As incidence slowly declines but prevalence climbs, Maryland, New York, Mississippi, Florida, and other high-burden states are living in the country’s cognitive future. The geography of Alzheimer’s is no longer a backdrop. It is the story.
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Disclosure: This article was developed with the assistance of AI and was subsequently reviewed, revised, and approved by our editorial team.
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