In the first nationally representative survey of the prevalence of cognitive impairment in more than 20 years, Columbia University researchers found that nearly 10% of U.S. adults age 65 and older have dementia, while another 22% have mild cognitive impairment. has. People with dementia and mild cognitive impairment are more likely to be older, have a lower level of education, and are racialized as black or Hispanic. Men and women have similar rates of dementia and mild cognitive impairment.
While dementia and mild cognitive impairment are known to be common in the United States, accurate, up-to-date measures of their national prevalence have been scarce.
“Such data is critical to understanding the causes, costs, and consequences of dementia and mild cognitive impairment in the United States, and to informing policies aimed at reducing their impact on patients, families, and public programs.” said Jennifer J. Manly, PhD, the study’s lead author and professor of neuropsychology in neurology at the Gertrude H. Sergievsky Center and the Taub Institute for Research on Alzheimer’s Disease and the Aging Brain at Columbia University.
Dementia rate 35% among over-90s
The study was based on data from 3,500 individuals who participated in the nationally representative Health and Retirement Study. Between 2016 and 2017, each participant completed an extensive series of neuropsychological tests and in-depth interviews, which were used to develop an algorithm for diagnosing dementia or mild cognitive impairment.
Dementia and Mild Cognitive Impairment
Dementia is characterized by cognitive problems that begin in adulthood and affect a person’s ability to perform everyday activities independently. Mild cognitive impairment is a classification assigned to people who are thought to transition between normal aging and dementia, but not everyone with mild cognitive impairment will develop dementia.
The rates of dementia and mild cognitive impairment rose sharply with age: 3% of people aged 65 to 69 had dementia, rising to 35% for people aged 90 and older.
“With the increasing longevity and aging of the baby boom generation, cognitive impairment is expected to increase significantly in the coming decades, impacting individuals, families and programs that provide care and services to people with dementia,” Manly says.
The economic impact of dementia, including unpaid caregiving, is estimated at $257 billion annually in the United States and $800 billion worldwide.
Differences in cognitive impairment are caused by exposure to structural and social inequalities
Unlike previous large studies of dementia in the United States, the participants in the new study are representative of older adults, allowing researchers to examine differences in the national prevalence of dementia and mild cognitive impairment by age, race and ethnicity, gender, and education. .
The data shows a disproportionate burden of dementia in older adults who self-identified as Black or African American, mild cognitive impairment in older adults who identify as Hispanic, and both categories of cognitive impairment in people who had fewer opportunities to receive education.
“Research on dementia in general is largely focused on highly educated people who are racialized as white,” Manly says. “This study is representative of the population of older adults and includes groups that have historically been excluded from dementia research but are at higher risk of developing cognitive impairment due to structural racism and income inequality. If we are interested in increasing health of the brain later in life, we need to know where we stand now and where to focus our resources.”