On Sept. 3, 2024, researchers at NORC at the University of Chicago and George Washington University’s Milken Institute School of Public Health reported that millions of Americans in Medicare had diagnostic evidence of dementia. The study was first comprehensive count of all Medicare beneficiaries of all ages with documented diagnosis of some form of 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.

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.