US Dementia Prevalence Estimates - NIA IMPACT Collaboratory

United States Dementia Prevalence Estimates among Medicare Beneficiaries

The IMPACT Collaboratory Technical Data Core has generated prevalence estimates of Alzheimer’s disease and related dementias (ADRD) for the Medicare population by geographic regions and settings of care. These data include the total number of Medicare beneficiaries, total number of beneficiaries with ADRD, and key demographic characteristics (age, sex, race, dual eligibility).

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Map of 2019 Adjusted Probability of ADRD by Hospital Referral Region among Fee-for-Service Medicare Beneficiaries

Data Sources Geographic levels Care Settings Medicare Insurance

Data Sources

Prevalence estimates are based on 100% files from the Centers for Medicare and Medicaid Services (CMS).

Data for 2020 and 2021 are available for both traditional fee-for-service and Medicare Advantage populations. Data for 2018 and 2019 are only available for traditional fee-for-service beneficiaries.

Estimates based on cell sizes less than 11 are suppressed according to the CMS cell suppression policy.

Geographic levels

Hospital Referral Region (HRR)
Hospital Service Area (HSA)
Primary Care Service Area (PCSA)

These data include the number of women and men and the number of Black, Hispanic and White beneficiaries with a dementia diagnosis in each service area. Many areas may not have all of these estimates due to the CMS cell suppression policy (i.e., cell sizes less than 11).

Years available: 2018, 2019, 2020, 2021

Care Settings

Hospitals (short stay)
Hospital-based emergency departments (ED)
Skilled nursing facilities (SNF)

Small hospitals, EDs and SNFs with few annual admissions among people with a dementia diagnosis may not have any data associated with them due to the CMS cell suppression policy (i.e., cell sizes less than 11).

Data are available, including facility names, for years 2018, 2019, 2020, 2021.

Medicare Insurance

Data for 2020 and 2021 are available for both traditional fee-for-service and Medicare Advantage populations. Data for 2018 and 2019 are only available for traditional fee-for-service beneficiaries.

Researchers should be mindful that the proportion of Medicare beneficiaries enrolled in Medicare Advantage plans has increased over time (from 37% in 2018 to 46% in 2021 and 51% in 2023) and varies widely by state and county (in 2023 from 60% in Michigan to 11% in Wyoming).*

*SOURCE: Kaiser Family Foundation CMS Medicare Advantage Enrollment Files, 2010-2023.

Bynum Dementia Algorithm

Prevalence estimates are created using the Bynum 1-Year Standard Algorithm for identifying Alzheimer’s Disease and Related Dementias in Medicare Claims
Prevalence estimates are created using the Bynum 1-Year Standard Algorithm for identifying Alzheimer’s Disease and Related Dementias in Medicare Claims