Meaning Reducing health disparities is a high-level national priority. Dementia is a widespread, burdensome, and costly condition with substantial variation in prevalence by education, sex, and racial and ethnic groups. While a decline in population prevalence has been firmly established, much less is known about trends in disparities, even whether they have increased or decreased. However, this knowledge is vital for public policy to address these disparities. In addition to the benefit to public policy, studying these subpopulations over time has the scientific benefit of establishing hypotheses about the causal mechanisms of dementia because different subpopulations and cohorts were differentially exposed to risk factors such as education, paid work, the provision of health care, and economic circumstances. |
Summary
This article presents estimates of the prevalence of dementia in the United States between 2000 and 2016 by age, sex, race and ethnicity, education, and a measure of lifetime income, using data from 21,442 people aged 65 years or older. more and 97,629 person-years of observations from a nationally representative survey, the Health and Retirement Study (HRS). The survey includes a variety of cognitive tests, and a subsample underwent clinical evaluation for dementia.
We developed a longitudinal model of latent variables of cognitive status, which we estimated using the Markov Chain Monte Carlo method. This model provides more precise estimates of dementia prevalence in population subgroups than methods previously used in the HRS.
Age-adjusted prevalence of dementia decreased from 12.2% in 2000 (95% CI, 11.7 to 12.7%) to 8.5% in 2016 (7.9 to 9.1%) in the population over 65 years old, a statistically significant decrease of 3.7 percentage points or 30.1%.
Women are more likely to live with dementia, but the sex difference has narrowed.
In the male subsample, we found a reduction in inequalities between education, income, and racial and ethnic groups; Among women, these inequalities also decreased, but less strongly. We observe a substantial increase in the level of education between 2000 and 2016 in the sample.
This change in composition can explain, in a statistical sense, about 40% of the reduction in the prevalence of dementia among men and 20% among women, while changes in the composition of the older population by age, race and ethnicity, and cardiovascular risk factors mattered less.
Comments
The prevalence of dementia in the U.S. is declining among people over age 65, dropping 3.7 percentage points between 2000 and 2016, according to a new study from the RAND Corporation.
The age-adjusted prevalence of dementia decreased from 12.2% of people over 65 years of age in 2000 to 8.5% of people over 65 years of age in 2016, a drop of almost a third from the 2000 level. The prevalence of dementia decreased throughout the period, but the rate of decline was most rapid between 2000 and 2004.
Differences in dementia prevalence between black men and white men narrowed, with dementia prevalence falling by 7.3 percentage points among black men compared to 2.7 percentage points among white men .
The findings are published in the journal Proceedings of the National Academy of Sciences .
"The reasons for the decline in dementia prevalence are not certain, but this trend is good news for older Americans and the systems that support them," said Péter Hudomiet, lead author of the study and an economist at RAND, an organization non-profit research. . “This decrease may help reduce the expected strain on families, nursing homes, and other support systems as the U.S. population ages.”
Michael D. Hurd and Susann Rohwedder of RAND are co-authors of the study.
Dementia prevalence was higher among women than men throughout the period, but the difference narrowed between 2000 and 2016. Among men, dementia prevalence decreased by 3.2 percentage points, from 10.2%. at 7.0%. The decline was largest among women: 3.9 percentage points, from 13.6% to 9.7%.
In 2021, about 6.2 million American adults aged 65 and older were living with dementia. Because age is the strongest risk factor for dementia, increasing life expectancy has been predicted to substantially increase the prevalence of Alzheimer’s disease and related dementias from about 50 million to 150 million worldwide. the world by 2050.
However, there is growing evidence that the age-adjusted prevalence of dementia has declined in developed countries, possibly due to rising education levels, a reduction in smoking, and better treatment of key cardiovascular risk factors. , such as high blood pressure.
Any changes in these age-specific rates have important implications for projected prevalence and associated costs, such as payments for nursing care by households, insurance companies, and the government.
The new RAND study employs a novel model to assess cognitive status based on a broad set of cognitive measures obtained from more than 21,000 people participating in the National Health and Retirement Study, a large population-representative survey that has been conducted for more than two decades.
The model increases the accuracy of dementia classification by using the longitudinal dimension of the data. Most importantly for the study of inequality, the model is built to ensure that dementia classification is calibrated within population subgroups and is therefore equipped to produce accurate estimates of dementia prevalence. by age, sex, education, race and ethnicity, and by a measure of lifetime earnings.
The RAND study found that education was a major factor contributing, in a statistical sense, to the reduction in dementia, explaining about 40% of the reduction in dementia prevalence among men and 20% of the reduction among women.
The fraction of college-educated men in the study increased from 21.5% in 2000 to 33.7% in 2016, and the fraction of college-educated women increased from 12.3% to 23% during this period.
Trends in education level differ between demographic groups, which may affect inequalities in dementia in the future. For example, while women traditionally had lower levels of education than men, among younger generations, women are more educated. While racial and ethnic minority groups still have lower levels of education than non-Hispanic white individuals, the gaps between racial and ethnic groups have narrowed.
“Closing the educational gap between racial and ethnic groups can be a powerful tool for reducing health inequalities in general and dementia-related inequalities in particular, an important goal of public health policy,” Hudomiet said.
The age-adjusted prevalence of dementia tended to be higher among racial and ethnic minority individuals, both among men and women. However, among men, the difference in prevalence between blacks and non-Hispanic whites narrowed, while it remained stable among women. Among non-Hispanic white men, the prevalence of dementia decreased from 9.3% to 6.6%. Among non-Hispanic black men, the rate fell from 17.2% to 9.9%.
Support for the study, which is titled “Trends in Inequalities in Dementia Prevalence in the US,” was provided by a grant from the National Institute on Aging. The RAND Society and Economic Wellbeing division actively seeks to improve the health, social and economic well-being of populations and communities around the world.
