Dementia prevalence is declining among older Americans, study finds
Study also finds decreases in disparities based on race and sex
Peer-Reviewed PublicationThe prevalence of dementia in the U.S. is declining among people over age 65, dropping 3.7 percentage points from 2000 to 2016, according to a new RAND Corporation study.
The age-adjusted prevalence of dementia declined from 12.2% of people over age 65 in 2000 to 8.5% of people over age 65 in 2016 – a nearly one-third drop from the 2000 level. The prevalence of dementia decreased over the entire period, but the rate of decline was more rapid between 2000 and 2004.
Differences in the prevalence of dementia between Black men and white men narrowed, with the prevalence of dementia dropping by 7.3 percentage points among Black men as compared to 2.7 percentage points among white men.
The findings are published in the latest edition of the journal Proceedings of the National Academy of Sciences.
“The reasons for the decline in the prevalence of dementia are not certain, but this trend is good news for older Americans and the systems that support them,” said Péter Hudomiet, the study's lead author and an economist at RAND, a nonprofit research organization. “This decline may help reduce the expected strain on families, nursing homes and other support systems as the American population ages.”
Michael D. Hurd and Susann Rohwedder of RAND are co-authors of the study.
The prevalence of dementia was higher among women than men over the entire period, but the difference shrank between 2000 and 2016. Among men, the prevalence of dementia decreased by 3.2 percentage points from 10.2% to 7.0%. The decrease was larger among women -- 3.9 percentage points from 13.6% to 9.7%.
In 2021, about 6.2 million U.S. adults aged 65 or older lived with dementia. Because age is the strongest risk factor for dementia, it has been predicted that increasing life expectancies will substantially increase the prevalence of Alzheimer’s disease and related dementias from about 50 million to 150 million worldwide by 2050.
However, there is growing evidence that age-adjusted dementia prevalence has been declining in developed countries, possibly because of rising levels of education, a reduction in smoking, and better treatment of key cardiovascular risk factors such as high blood pressure.
Any change in these age-specific rates has 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 elicited from more than 21,000 people who participate in the national Health and Retirement Study, a large population-representative survey that has been fielded for more than two decades.
The model increases the precision of dementia classification by using the longitudinal dimension of the data. Importantly for the study of inequality, the model is constructed to ensure the dementia classification is calibrated within population subgroups and, therefore, it is 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 an important factor that contributed, 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% over this period.
Trends in the level of education differ across 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 education levels than non-Hispanic White individuals, the gaps across racial and ethnic groups have shrunk.
“Closing the education gap across racial and ethnic groups may be a powerful tool to reduce health inequalities in general and dementia inequalities in particular, an important public health policy goal,” 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 the prevalence between non-Hispanic Black and White individuals 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 the Prevalence of Dementia in the U.S.,” was provided by a grant from National Institute on Aging.
The RAND Social and Economic Well-Being division seeks to actively improve the health, social and economic well-being of populations and communities throughout the world.
JOURNAL
Proceedings of the National Academy of Sciences
METHOD OF RESEARCH
Data/statistical analysis
SUBJECT OF RESEARCH
People
ARTICLE TITLE
Trends in inequalities in the prevalence of dementia in the United States
ARTICLE PUBLICATION DATE
7-Nov-2022
Using SNAP benefits can help your
memory
Food program may slow brain aging by two years
Peer-Reviewed PublicationEligible older adults who participate in the Supplemental Nutrition Assistance Program (SNAP) in the United States may have slower memory decline than eligible people who do not participate, according to a new study at Columbia University Mailman School of Public Health. The researchers found that those who used SNAP had about two fewer years of cognitive aging over a 10-year period compared with those who didn’t use SNAP.
The study is published online in Neurology®, the medical journal of the American Academy of Neurology. SNAP is a government program to help low-income households achieve food security through financial benefits used to purchase food.
“Less than half of the older adults who are eligible for SNAP actually participate, yet our findings showed that people using SNAP experienced two fewer years of cognitive aging over 10 years compared to those who did not use the program,” said senior author Adina Zeki Al Hazzouri, PhD, assistant professor of epidemiology at Columbia University Mailman School of Public Health. “With the number of people with Alzheimer’s disease and other dementias expected to increase, this low participation is a huge, missed opportunity for dementia prevention.”
Zeki Al Hazzouri said increasing education and outreach, reducing stigma and simplifying the application process could all help increase the participation rate for older adults.
The study involved 3,555 people with an average age of 66 who were eligible for SNAP benefits. Of those people, 559 were eligible SNAP users and 2,996 were eligible but did not use the program.
Researchers measured memory function every two years over 20 years. People were asked to complete memory and thinking tests, such as recalling a list of words and answering questions about what they can remember in their everyday lives.
At the beginning of the study, SNAP users had lower socioeconomic status and a greater number of chronic conditions than those who did not participate in the program, so researchers used techniques to account for those differences. After adjusting for the differences between the two groups, researchers found that while SNAP users had worse memory scores at the start of the study, they had slower rates of memory decline compared to non-users over the course of the study. In particular, researchers found that those who used SNAP had about two fewer years of cognitive aging over a 10-year period compared with those who didn’t use SNAP.
“While SNAP’s primary goal is to reduce food insecurity among low-income households and to increase access to higher quantity and quality foods, eating healthier may also benefit brain health,” said study first author Peiyi Lu, PhD and a postdoctoral research scientist in the Department of Epidemiology at Columbia Mailman School. “SNAP may also reduce stress and overall financial hardship, which has been linked to premature cognitive aging and reduced brain health. Future research should explore these underlying impacts.”
Co-authors are Katrina Kezios and Sebastian Calonico, Columbia University Mailman School of Public Health; Jongseong Lee and Christopher Wimer, Columbia University
Columbia University Mailman School of Public Health
Founded in 1922, the Columbia University Mailman School of Public Health pursues an agenda of research, education, and service to address the critical and complex public health issues affecting New Yorkers, the nation and the world. The Columbia Mailman School is the fourth largest recipient of NIH grants among schools of public health. Its nearly 300 multi-disciplinary faculty members work in more than 100 countries around the world, addressing such issues as preventing infectious and chronic diseases, environmental health, maternal and child health, health policy, climate change and health, and public health preparedness. It is a leader in public health education with more than 1,300 graduate students from 55 nations pursuing a variety of master’s and doctoral degree programs. The Columbia Mailman School is also home to numerous world-renowned research centers, including ICAP and the Center for Infection and Immunity. For more information, please visit www.mailman.columbia.edu.
JOURNAL
Neurology
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