Dementia prevalence declining among older Americans: Study

According to a new RAND Corporation study, the prevalence of dementia among adults over the age of 65 is declining in the United States, dropping 3.7 percentage points between 2000 and 2016.
The age-adjusted prevalence of dementia fell from 12.2% of individuals over the age of 65 in 2000 to 8.5% of people over the age of 65 in 2016 – a nearly one-third reduction from the 2000 figure. Dementia prevalence fell throughout the study period, but the pace of reduction was faster between 2000 and 2004.

The gap in dementia prevalence between Black men and white men has shrunk, with the prevalence of dementia reducing by 7.3 percentage points among Black men and 2.7 percentage points among white men.
The findings were published in the journal Proceedings of the National Academy of Sciences in the most recent issue.
“The causes for the drop in dementia frequency are unknown, but this trend is excellent news for older Americans and the institutions that serve them,” said Peter Hudomiet, principal author of the study and an economist at RAND, a nonprofit research group. “As the American population ages, this drop may help alleviate the load on families, nursing homes, and other support services.”

The study’s co-authors are RAND’s Michael D. Hurd and Susann Rohwedder.
Throughout the study period, women had a greater frequency of dementia than males, however the gap narrowed between 2000 and 2016. The frequency of dementia in men fell by 3.2 percentage points, from 10.2% to 7.0%. Women had a bigger drop, dropping 3.9 percentage points from 13.6% to 9.7%.
In 2021, around 6.2 million persons 65 and older in the United States will have dementia. Because age is the most important risk factor for dementia, rising life expectancy is expected to raise the global incidence of Alzheimer’s disease and associated dementias from 50 million to 150 million by 2050.

However, there is mounting evidence that age-adjusted dementia incidence is dropping in industrialised nations, probably as a result of more education, a decrease in smoking, and improved treatment of significant cardiovascular risk factors such as high blood pressure.
Any change in these age-specific rates has significant consequences for expected prevalence and related expenditures, such as household, insurance, and government payments for nursing care.
The new RAND study applies an unique model to assess cognitive health based on a wide range of cognitive measures elicited from more than 21,000 adults who take part in the national Health and Retirement Study, a large population-representative survey that has been conducted for more than two decades.

By utilising the longitudinal dimension of the data, the model improves the precision of dementia classification. Importantly for the study of inequality, the model is built to guarantee that the dementia categorization is calibrated among population subgroups, and therefore it can generate reliable estimates of dementia prevalence by age, gender, education, race and ethnicity, and a measure of lifetime wages.
According to the RAND research, education was a major factor that contributed statistically to the reduction in dementia prevalence, accounting for approximately 40% of the reduction in dementia prevalence among men and 20% of the reduction in dementia prevalence among women.

The study’s proportion of college-educated men climbed from 21.5% in 2000 to 33.7% in 2016, while the proportion of college-educated women increased from 12.3% to 23% during the same period.
Education trends fluctuate between demographic groupings, which may impact dementia inequities in the future. For example, while women have traditionally had lower levels of education than males, women are becoming more educated among younger generations. While racial and ethnic minority groups continue to have lower education levels than non-Hispanic White people, the disparities between racial and ethnic groupings have narrowed.

“Closing the education gap across racial and ethnic groups might be a significant instrument for reducing health inequities in general, and dementia inequalities in particular,” Hudomiet added.
The age-adjusted prevalence of dementia was greater among racial and ethnic minority people, both men and women. However, the gap in frequency between non-Hispanic Black and White adults declined among males while remaining steady among women. The prevalence of dementia among non-Hispanic White males fell from 9.3% to 6.6%. The percentage declined from 17.2% to 9.9% among non-Hispanic Black men.

A grant from the National Institute on Aging provided funding for the study, titled “Trends in Inequalities in the Prevalence of Dementia in the United States.”
The RAND Social and Economic Well-Being division strives to actively enhance the health, social, and economic well-being of populations and communities worldwide.