1 in 10 older Americans are living with dementia, study reveals

NEW YORK — It’s common, even expected, for older adults to deal with some level of forgetfulness as they grow older. However, researchers from Columbia University report that a troublingly high percentage of older Americans have full-fledged dementia.

This project, the first nationally representative study of cognitive impairment prevalence in more than 20 years, also finds 22 percent of older U.S. adults have mild cognitive impairment.

While study authors say males and females typically display similar rates of dementia and mild cognitive impairment, people diagnosed with either condition are more likely to be older, have lower levels of education, and be either Black or Hispanic. It isn’t a secret that dementia and cognitive decline during old age is common among U.S. seniors, but exact numbers and figures on a national scale have been hard to come by up until now.

“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,” says lead study author Jennifer J. Manly, PhD, 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, in a university release.

1 in 3 people over 90 have dementia

This research is based on data pertaining to 3,500 individuals enrolled in the nationally representative Health and Retirement Study. Between 2016 and 2017, each and every participant completed a comprehensive array of neuropsychological tests and in-depth interviews, which researchers used to construct an algorithm for diagnosing dementia or mild cognitive impairment.

For reference, dementia usually begins with cognitive difficulties that start during adulthood and gradually worsen over time. They eventually impede a person’s capacity to function independently on a day-to-day basis. Mild cognitive impairment, on the other hand, is often a transitional state between normal aging and dementia. It’s important to note, however, that not everyone who has mild cognitive impairment will go on to develop dementia.

Among participants in the study, dementia and mild cognitive impairment rates increased with age; three percent of people between 65 and 69 years-old had dementia, while 35 percent of those 90 and older had dementia.

“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,” Prof. Manly adds.

Caring for those with dementia is costly to society

There’s also the economic impact of dementia to consider. Including unpaid family caregiving, estimates find that dementia costs $257 billion per year in the United States alone and $800 billion worldwide.

Dissimilar to previous studies focusing on U.S. dementia rates, the seniors examined in this study were representative of older adults, which enabled researchers to examine various differences in the national prevalence of dementia and mild cognitive impairment according to factors such as age, race and ethnicity, gender, and education.

That analysis suggests a disproportionate dementia burden for older adults self-identifying as Black or African American, as well as a greater burden of mild cognitive impairment among older adults identifying as Hispanic. Finally, there were higher rates of both categories of cognitive impairment among people who had fewer opportunities to obtain education.

“Dementia research in general has largely focused on college-educated people who are racialized as white,” Prof. Manly concludes. “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.”

The study is published in JAMA Neurology.

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