A new study found that nearly 1 in 10 U.S. adults 65 and older have dementia, while an additional 22% have mild cognitive impairment.
The research, led by Columbia University Irving Medical Center and published Monday in the journal JAMA Neurology, included 3,500 people enrolled in the Health and Retirement Study, a long-term survey project spearheaded by the National Institute on Aging and the Social Security Administration.
Participants completed neuropsychological tests and detailed interviews between 2016 and 2017. The team of researchers used the responses to develop an algorithm for diagnosing dementia or cognitive impairment.
The study represents the first nationally representative probe into the prevalence in cognitive impairment in two decades, researchers said.
“Such data are critical for understanding the causes, costs and consequences of dementia and mild cognitive impairment in the United States and for informing policies aimed at reducing their impact on patients, families and public programs,” Dr. Jennifer Manly, a Columbia University neurology professor and the study’s lead author, said in a release.
Black or Hispanic people were more likely to have dementia and mild cognitive impairment, the researchers found, along with people with lower levels of education, underscoring significant disparities in the development of cognitive issues.
Fifteen percent who identified as Black in the study were diagnosed with dementia, and an additional 22% had mild cognitive impairment. Ten percent of Hispanic participants had dementia, but cognitive issues affected 28% of this group, according to the study.
Comparatively, 9% of white participants had dementia and 21% had mild cognitive impairment.
The researchers also found a stark difference between those who had less than high school education and participants with at least a college degree. Thirteen percent of people without their high school diploma had dementia, compared to 9% who completed higher education.
Experts consider higher education attainment to be among the factors defending against cognitive decline in older age.
The disproportionate impact of dementia on older minority groups, the study authors said, warrants additional research to assess whether disparities are widening or closing over time.
By better understanding the gaps in dementia research and which groups are at greatest risk, policy makers can help shape future public health policy, the researchers said.
“Dementia research in general has largely focused on college-educated people who are racialized as white,” Manly said. “This study is representative of the population of older adults and includes groups that have been historically excluded from dementia research but are at higher risk of developing cognitive impairment because of structural racism and income inequality.”
“If we’re interested in increasing brain health equity in later life, we need to know where we stand now and where to direct our resources,” Manly added.
The prevalence of dementia also increased significantly with age. While just 4% of people 65-69 within the study had dementia, that total rose to 35% for people 90 and older.
Dementia already costs the U.S. around $257 billion per year, according to the study, with that total potentially rising as the country ages.
“With increasing longevity and the aging of the baby boom generation, cognitive impairment is projected to increase significantly over the next few decades, affecting individuals, families, and programs that provide care and services for people with dementia,” Manly said.
Recent studies have found physical activities like brisk walks can significantly slash the risk of dementia.
The COVID-19 pandemic has also sparked new research into dementia. Adults who contracted COVID-19 have a significantly higher risk of receiving a new Alzheimer’s diagnosis within a year — the most common form of dementia — underscoring the significant neurological impacts wrought by the pandemic.
Dementia symptoms include memory loss, confusion, and difficulty speaking and writing.
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