Summary: A large population study of more than 25 million traditional Medicare beneficiaries shows a complex shift in dementia patterns in the United States: annual new diagnoses have declined, but the total number of older adults living with dementia has increased. Between 2015 and 2021, age- and sex-adjusted incidence dropped from 3.5% to 2.8%, while prevalence rose to approximately 11.8% of beneficiaries.
These findings highlight an urgent need to expand long-term care capacity, strengthen caregiver support, and address persistent health inequities. The study identifies clear disparities by sex, race and ethnicity, and neighborhood socioeconomic status, with women, racial and ethnic minority groups, and residents of disadvantaged areas experiencing higher dementia burdens.
Key facts
- Incidence versus prevalence: New dementia cases per year fell, but overall prevalence among Medicare beneficiaries increased to nearly 12% by 2021.
- Health disparities: Black beneficiaries had the highest incidence in 2021, and higher rates were also seen among women and people living in socioeconomically disadvantaged neighborhoods.
- Longer survival with dementia: Improvements in survival mean more people are living longer with dementia, increasing long-term care and support needs.
Source: UNC
A major new population-based analysis published in The BMJ examined trends in dementia incidence and prevalence across a nationally representative group of U.S. Medicare beneficiaries aged 66 and older. Led by researchers at the UNC School of Medicine, Duke University School of Medicine, and the University of Texas Southwestern Medical Center, the study provides timely evidence for policymakers, health systems, and caregivers planning for the growing dementia care demand.
“Fewer people are being newly diagnosed with dementia each year, which is encouraging,” said Jay B. Lusk, MD, MBA, a preventive medicine resident at the UNC Department of Family Medicine and visiting research scholar at Duke University. “However, because people with dementia are living longer, the number of older adults requiring long-term care and caregiver support continues to grow. That combination creates a pressing need for equitable policies and resources across communities.”
Globally, dementia remains a leading cause of disability and dependency among older adults. Projected increases in the number of people living with dementia will place additional pressure on families, clinicians, long-term care facilities, and public health systems—especially in underserved and socioeconomically disadvantaged communities.
Study authors examined Medicare fee-for-service claims for beneficiaries aged 66 or older who maintained continuous enrollment for at least one year between 2015 and 2021. The analysis evaluated incidence (new cases per person-years) and prevalence (percentage of beneficiaries living with a diagnosis) and reported results stratified by age, sex, race and ethnicity, and neighborhood socioeconomic status.
Major findings included:
- From 2015 to 2021, the age- and sex-standardized incidence of dementia decreased from 3.5% to 2.8%.
- Over the same period, prevalence increased from 10.5% to 11.8%, amounting to roughly 2.9 million beneficiaries—about 12% of traditional Medicare enrollees—living with a dementia diagnosis by 2021.
- In 2021, incidence was highest among Black beneficiaries (3.1%), followed by White beneficiaries (2.8%) and Hispanic beneficiaries (2.6%).
- Across the study period, higher dementia rates were consistently observed among women, racial and ethnic minorities, and people residing in socioeconomically disadvantaged neighborhoods.
Funding: The study was supported by the Duke‑UNC Alzheimer’s Disease Research Center (ADRC) under award P30AG072958 from the National Institute on Aging, by the Alzheimer’s Association (award 24HPE-1287087), and by the Duke University Department of Neurology.
About this dementia research news
Author: Kendall Daniels
Source: UNC
Contact: Kendall Daniels – UNC
Image credit: Neuroscience News
Original research: Open access. Title: “Incidence and prevalence of dementia among US Medicare beneficiaries, 2015–21: population based study” by Jay B. Lusk et al., published in BMJ (DOI: 10.1136/bmj-2024-083034).
Abstract (summary)
Objective: To measure dementia incidence and prevalence in a nationally representative cohort of U.S. Medicare beneficiaries and to describe variation across key subgroups.
Design and setting: A population-based study using nationwide Medicare fee-for-service data from 2015 to 2021.
Participants: Fee-for-service Medicare beneficiaries aged 66 or older with at least one year of continuous enrollment.
Main measures: Annual incidence (new cases per person-years) and prevalence (percentage of beneficiaries with a recorded diagnosis), with results stratified by age, sex, race/ethnicity, and neighborhood socioeconomic status.
Results: The study documented 5,025,039 incident dementia cases from 2015 to 2021. Age- and sex-standardized incidence declined from 3.5% to 2.8%, while prevalence rose from 10.5% to 11.8%. Subgroup analyses showed persistent disparities: incidence was highest among Black beneficiaries in both 2015 and 2021, and higher burdens were consistently seen among women and residents of disadvantaged neighborhoods. Differences between racial and ethnic groups narrowed somewhat over the study period.
Conclusions: Although annual dementia incidence fell between 2015 and 2021, prevalence increased because people are living longer with dementia. These trends, together with persistent disparities by race/ethnicity, sex, and neighborhood socioeconomic status, point to the need for targeted public health strategies, expanded long-term care infrastructure, and policies that promote equity in dementia prevention, diagnosis, and care.