Epidemiological information about dementia is badly needed in the United States. 

Alzheimer’s disease and related dementias (ADRD) are brain conditions that impair brain functioning, causing progressive deterioration in memory, language processing, and bodily function, ultimately resulting in death. ADRD is the sixth leading cause of reported death in the United States and cost the U.S. health care system over $305 billion in 2020.

The United States has lacked a surveillance system for ADRD, limiting our understanding of its total burden and the distribution of this burden by demographic group and geography. The 2020 update to the National Alzheimer’s Project Act’s National Plan to Address Alzheimer’s Disease recognizes the need for increased surveillance of dementia, stating, “Data and surveillance efforts are paramount to tracking the burden … and assist with understanding health disparities among populations such as racial and ethnic minorities, low-income populations, rural residents, and sexual and gender minorities.”

Innovative surveillance systems based on secondary data sources can help the research community and public better understand ADRD epidemiology and plan public health services.

NORC created a surveillance system using Medicare claims and encounter data.

Medicare data on people diagnosed with ADRD can be used to estimate the prevalence, incidence, and other outcomes of ADRD. Medicare provides nearly universal coverage for people ages 65 and older, so it can provide highly accurate counts of people with diagnoses for ADRD, as most with the condition are older than 65.

However, the data have limitations. Existing case definitions of which diagnoses indicate ADRD are highly variable. Many dementia symptoms are unrecognized in clinical settings or lack a diagnosis code in the Medicare records that can be used to identify dementia. Diagnoses among people with dementia symptoms likely vary by race and ethnicity, gender, and geographic region.

To address these limitations, NORC first conducted a systematic review of published diagnostic code case definitions to create evidence-supported definitions that can be used for national surveillance. We are next validating the data, linking Medicare claims data to dementia assessment information contained in the Health and Retirement Survey. This validation will help us refine our case definitions in future system updates and estimate how many undiagnosed cases exist for every diagnosed case and how this rate varies by demography and region.

Finally, we engaged NORC’s experts in data visualization, geographic information systems, data privacy, and communications and website design to develop the Dementia DataHub, an intuitive, visually appealing website that allows access to and visualization of granular dementia data while safeguarding individual privacy.