CHICAGO, September 3, 2024 – In the first comprehensive count of all Medicare beneficiaries of all ages with documented diagnosis of some form of dementia, a new study published today in JAMA Network Open estimated that millions of Americans in Medicare had diagnostic evidence of dementia. The study, conducted by researchers at NORC at the University of Chicago and George Washington University’s Milken Institute School of Public Health, estimated that in 2019, 5.4 million Medicare beneficiaries had diagnoses indicating likely or highly likely dementia, and an additional 2.6 million people had diagnoses indicating possible dementia. 

The study, “Case Definition for Diagnosed Alzheimer Disease and Related Dementias in Medicare,” developed and applied a new case definition of claims-based dementia identification informed by a systematic review of previous definitions used across the research community. Dementia causes progressive deterioration in memory, language, and bodily function and ultimately results in death. The study used a new diagnostic and drug code case definition based on a systematic review of previous research. 

“This new case definition for identifying dementia is novel in that it was driven by researcher consensus and data analysis,” said Kan Gianattasio, the first author of the study and a research scientist in Health Care Evaluation at NORC at the University of Chicago. “It is an important first step toward our goal of developing a refined national surveillance system that can be used by public health researchers and practitioners, policymakers, and medical professionals for dementia monitoring and research purposes.”   

The project team used the case definition developed in the paper to create the Dementia DataHub, a public website that provides detailed geographic and demographic data on different types of diagnosed dementia in Medicare at the national, state, and county level. The Dementia DataHub currently includes estimates for beneficiaries enrolled in Medicare in 2020. 

According to the study:

• Approximately 9.1 percent of all Medicare beneficiaries, and 10.9 percent of beneficiaries ages 65 and older with Part A and B coverage, had diagnostic evidence of at least likely dementia.
• 4.3 percent of all beneficiaries and 4.8 percent of those ages 65 and older with Part A and B coverage had diagnostic evidence that could possibly indicate dementia. 
• Beneficiaries with diagnostic evidence of dementia were older, frailer, had greater proportions of dual Medicaid eligibility and long-term care utilization, were more likely to die in 2019, and incurred greater all-cause Medicare expenditures than those without diagnostic evidence of dementia. 

The authors caution that their research includes only people who received documentation for a diagnosis or prescription drug through Medicare; prior research has indicated that as many as up to 61 percent of dementia patients in the United States are undiagnosed.

According to the Dementia DataHub:

• Rates of diagnosed dementia varied by state and U.S. county. In 2020, Puerto Rico (10.6 percent), Florida (8.2 percent), Texas (8.1 percent), Connecticut (8.0 percent), and New York (7.9 percent) had the highest burden of “highly likely” dementia among their Medicare beneficiaries.
• Idaho (5.3 percent), Montana (5.1 percent), Vermont (5.0 percent), Wyoming (4.9 percent), and Alaska (4.9 percent) had the lowest burden (excluding territories other than Puerto Rico). 

Research regarding the reasons for differences in diagnosis rates by demographics and geography is ongoing. 

The Dementia DataHub draws data from Medicare, which provides nearly universal health coverage for people ages 65 and older, and coverage for selected groups younger than 65 such as those who qualify because of disability. NORC and its collaborating organizations analyzed Medicare fee-for-service claims and Medicare Advantage encounter data to measure the scope and outcomes of Alzheimer’s and related dementias (ADRD). Among Medicare beneficiaries enrolled in 2020, over 8.1 million were coded as having some form of diagnosed dementia.

“We developed the Dementia DataHub to provide the research community and the public with data visualizations and tools to explore the epidemiology of diagnosed dementia in the United States,” said David Rein, program area director in NORC’s Public Health Analytics Program Area and principal investigator of the grant that supports the project. “The DataHub provides the first counts and statistics on diagnosed dementia prevalence, incidence, all-cause Medicare payments, mortality, and COVID-19 infection, at the national, state, and county levels, and uses the internet to facilitate the use of these data. We hope our work can help others better understand regional and demographic variation in diagnosed dementia and use the information to reduce the impact of dementia on individuals and families nationwide.”

The Dementia DataHub is a joint effort led by NORC at the University of Chicago, with intellectual and technical support from George Washington University’s Milken Institute School of Public Health and KPMG LLP. The DataHub is funded by the National Institute on Aging, part of the National Institutes of Health, through Grant R01-AG-075730. The content of both the paper and the DataHub is solely the responsibility of the project team and does not necessarily represent the official views of the National Institutes of Health.

“We needed a nationwide dementia surveillance system to really understand the scope of the dementia epidemic, direct critical support to those in need, address disparities, and create informed policy solutions,” said Dr. Melinda Power, the director of George Washington University’s Institute for Brain Health and Dementia, and co-investigator on the project. “The Dementia DataHub fills that need.” 

Multidisciplinary experts from across NORC contributed to building a website that presents our findings via visually appealing and easily accessible interactive maps and dashboards, allowing users to delve deep while safeguarding individual privacy. The DataHub also contains a summary of the website’s data that will eventually be updated to include the drivers and determinants of geographic variation in dementia outcomes. 

“The prevalence of Alzheimer’s and related dementias is rising fast, and the impact is not equitable. Policymakers and advocates need the best data possible to track and fight back against this disease. The Dementia Datahub provides all of us with actionable insights that can enable us to fight back against Alzheimer’s with greater efficiency, effectiveness, and precision. Together with our National Alzheimer’s Disease Index, this information enables us to better execute on our mission to end the disease—for everyone, everywhere,” said Russ Paulsen, chief operating officer of UsAgainstAlzheimer’s, a leading Alzheimer’s not-for-profit working on prevention, early detection and diagnosis and equal access to treatments for ADRD. UsAgainstAlzheimer’s has been briefed about the Dementia DataHub but was not involved with project.