Alzheimer’s disease is a progressive neurodegenerative disorder that gradually impairs memory, thinking, and behavior, ultimately interfering with daily life. It is the most common cause of dementia, affecting millions of older adults across the United States. While the disease is a national health challenge, its prevalence is not evenly distributed across the country. This analysis seeks to identify the specific state exhibiting the highest rate of diagnosis and explore the statistical and demographic factors that contribute to this geographic variation.
Identifying the State with the Highest Prevalence
The state with the highest estimated prevalence of Alzheimer’s disease among its older population is Maryland. Research analyzing data across all U.S. counties estimates that 12.9% of Maryland residents aged 65 and older are currently living with the disease. This figure represents the proportion of the state’s senior population diagnosed with the condition, placing Maryland at the top of the national prevalence rankings. Within the state, particularly high concentrations are found in urban centers, such as Baltimore City, where the prevalence rate is estimated to be 16.6%.
How Geographic Variation in Alzheimer’s Rates is Measured
Measuring the geographic spread of Alzheimer’s disease relies primarily on calculating prevalence rates. Prevalence represents the total number of diagnosed cases existing in a population at a specific time. This metric is distinct from incidence, which tracks only new cases, or mortality rates, which measure deaths where the condition is a contributing factor. Researchers estimate state and county prevalence by combining cognitive data from longitudinal population studies, such as the Chicago Health and Aging Project, with demographic data from the U.S. Census.
This methodology allows scientists to project rates based on regional population characteristics, overcoming the limitations of relying solely on diagnosed cases. Data collection challenges include variations in diagnostic practices and reliance on administrative data like Medicare claims. Since regions have varying levels of access to specialized care, this influences how frequently and how early a dementia diagnosis is officially recorded. Projection models help standardize these estimates for more accurate state-by-state comparisons of the actual burden of the disease.
Key Demographic Drivers of Regional Rates
Age Structure
A state’s Alzheimer’s prevalence rate is largely driven by the age structure of its population, as age is the single greatest risk factor for the disease. States with a higher proportion of residents aged 85 and older naturally exhibit a higher prevalence. The concentration of the oldest population in certain regions, often due to retirement migration patterns, significantly elevates the overall state rate. This explains why many states in the Sun Belt or those with established retirement communities often appear near the top of the rankings.
Health Disparities and Risk Factors
Differences in the racial and ethnic composition of a state’s population also play a substantial role in geographic variation. Older Black Americans are estimated to be about twice as likely to have Alzheimer’s compared to older White Americans. Older Hispanic Americans are estimated to be about one and a half times as likely to have the disease. States with larger Black or Hispanic populations, such as Mississippi and Florida, therefore have higher prevalence rates due to these health disparities. Furthermore, regions with high rates of cardiovascular risk factors, such as diabetes and obesity, see an increased risk of dementia, as these issues are closely linked to cognitive decline.
The National Landscape and State Rankings
The geographic analysis of Alzheimer’s prevalence reveals a distinct clustering of high-rate states primarily in the eastern and southeastern regions of the country. Following Maryland (12.9%), other states reporting high prevalence rates among their older populations include:
- New York (12.7%)
- Mississippi (12.5%)
- Florida (12.5%)
Other states rounding out the top ten include Louisiana, New Jersey, California, and Illinois.
It is important to distinguish between a state’s prevalence rate and the total number of people living with the condition. While Maryland has the highest rate, states with very large total populations, such as California, Florida, and Texas, have the highest overall number of individuals with Alzheimer’s disease. Conversely, states in the western and northwestern U.S. typically report the lowest prevalence rates. Understanding this national landscape helps public health officials direct resources to areas with the greatest need, whether defined by a high proportion of affected individuals or a high absolute count of cases.