Fewer Americans Developing Dementia, More Living With It

New cases of dementia declined in the United States from 2015 to 2021, possibly due to better risk factor management, but the number of individuals living with the disease continued to tick upward, likely due to the aging of the population, researchers reported. 

“We’re seeing encouraging signs that fewer people are being newly diagnosed with dementia each year,” Jay B. Lusk, MD, MBA, who worked on the study, said in a news release.

“At the same time, people with dementia are living longer than before, which underscores the need for long-term care planning, caregiver support, and equitable dementia care delivery,” said Lusk, preventive medicine resident at the Department of Family Medicine, University of North Carolina at Chapel Hill, and visiting research scholar at Duke University, Durham, North Carolina.

The study was published online on May 20 in The BMJ.

More, Better Services Needed

An analysis of claims data showed that between 2015 and 2021, approximately five million cases of incident dementia were documented among traditional fee-for-service Medicare beneficiaries.

After accounting for differences in age and sex, the overall incidence of dementia decreased 3.5% in 2015 to 2.8% in 2021. During the same period, the prevalence of dementia rose from 10.5% to 11.8%.

“Although the overall incidence of dementia decreased over the study period, prevalence increased substantially, and our results indicate that nearly 2.9 million fee-for-service Medicare beneficiaries and nearly 4.5 million Medicare beneficiaries (including projections to the Medicare Advantage population) were likely living with a diagnosis of dementia in 2021,” Lusk and colleagues wrote.

While the incidence of dementia was higher in men than in women in 2015 (3.5% vs 3.4%) — a difference that widened by 2021 (2.9% vs 2.6%) — most people with dementia in 2021 were women (60%), likely because more women live long enough to develop dementia.

The burden of dementia was unequally distributed, with the highest incidence and prevalence of dementia among Black beneficiaries and those living in socioeconomically disadvantaged neighborhoods.

These findings “highlight not just the need for improvement in services for people living with dementia in communities where higher incidence and prevalence might be expected but also the need to implement policies for improvement in risk factor profiles across populations from early life onwards,” Lusk and colleagues said.

Authors of a linked editorial said the findings “highlight not just the need for improvement in services for people living with dementia in communities where higher incidence and prevalence might be expected but also the need to implement policies for improvement in risk factor profiles across populations from early life onwards.”

“Politicians and many others are calling for early detection without clear evidence of benefit. Reducing life course inequalities is probably the greatest intervention that any society can do to push morbidity from its risk factors and the syndromal presentation back as close to late life death as possible,” Sara Ahmadi-Abhari, MD, PhD, with Imperial College London, London, England, and Carol Brayne, MD, with University of Cambridge, Cambridge, England, wrote.

The study received no commercial funding. The authors and editorial writers declared having no relevant disclosures.