New cases of dementia are decreasing while the prevalence continues to increase due to population aging

New cases of dementia are decreasing while the prevalence continues to increase due to population aging

New cases of dementia in the United States fell from 2015 to 2021, but the number of people living with the condition continued to rise due to population agingThe BMJToday.

Additionally, a greater burden of dementia was observed in marginalized and low-resource communities, highlighting the importance of policy approaches to promote equitable dementia care, the researchers say.

Dementia is estimated to more than double by 2060 to affect nearly 14 million people in the United States, with widespread social and economic impacts. However, high-quality evidence on recent trends in new cases (incidence) and prevalence (existing cases) of dementia in routine clinical practice is scarce.

To address this, researchers used medical claims data to determine the incidence and prevalence of dementia by race, gender and neighborhood in more than 5 million claims for Medicare beneficiaries aged 66 or older between 2015 and 2021.

After accounting for differences in age and gender, the overall incidence of dementia decreased from 3.5% to 2.8% between 2015 and 2021, but the prevalence increased from 10.5% to 11.8% during this time.

The male beneficiaries had a higher incidence than the female beneficiaries in 2015 (3.5% v 3.4%), which increased in 2021 (2.9% v 2.6%).

To give these numbers some context, the authors note that while men have a higher incidence than women of the same age, the majority of people with dementia are female (60% in 2021). Therefore, the population-level impact on dementia is most prominent in women (probably because more women live long enough to develop dementia).

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

For example, the incidence was highest in 2015 for black beneficiaries (4.2%), followed by Hispanic beneficiaries (3.7%) and white beneficiaries (3.4%), and in 2021 for black beneficiaries (3.1%), followed by white beneficiaries (2.8%) and Hispanic beneficiaries (2.6%).

Possible reasons for the reduced incidence of dementia include better treatment of cardiovascular risk factors and Covid-19 deaths in patients who would otherwise have been diagnosed with dementia, while the increase in prevalence is likely due to more people surviving long enough to develop dementia or more people living longer after being diagnosed with dementia, for example the authors.

This is an observational study, so no firm conclusions can be drawn about cause and effect, and the authors acknowledge several limitations, including that Medicare claims may not be completely accurate, limited in their classification of race and ethnicity, and may not apply to patients with different insurance coverage.

Still, they say their findings are based on a large national sample of routinely collected data, which allowed them to accurately reflect diagnostic patterns seen in general clinical practice and fill an important gap in the literature.

They call for further studies to examine the mechanisms of the observed disparities and say the disparities in these measures by race/ethnicity, gender, and neighborhood socioeconomic status should motivate future actions to promote health equity.

These results are consistent with those of other studies, but using routine data to uncover underlying trends poses challenges, British researchers say in a linked editorial.

For example, they point out that for marginalized minorities who are underrepresented in Medicare fee-for-service plans, true disparities through the area deduction index are larger than those reported. Better health surveillance, greater awareness and diagnosis at an earlier stage could also increase the numbers for the more vulnerable groups and further mask socioeconomic inequalities.

Therefore, these findings say that “not only is there a need to improve services for people with dementia in communities where higher incidence and prevalence are expected, but also a need to develop policies to improve risk factor profiles across populations.”

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