Image of an elderly nursing home resident receiving help with feeding by a nursing assistant

Ten percent of older adults in the United States have dementia and another 22% have cognitive impairment, finds the first such national study in two decades. The burden of these conditions rests heavily in older Black and Hispanic adults and those with lower education, investigators also reported.

“With increasing longevity and the aging of the Baby Boom generation, cognitive impairment is projected to increase significantly over the next few decades,” said lead author Jennifer J. Manly, PhD, of Columbia University in New York City. This will in turn affect “individuals, families and programs that provide care and services for people with dementia,” she said.

Rates and age

Study participants included nearly 3,500 individuals enrolled in the national Health and Retirement Study who were 65 years or older in 2016. Each was given neuropsychological tests and interviews between 2016 and 2017, the results of which helped create an algorithm for diagnosis. 

The rates of dementia and mild cognitive impairment climbed with every five-year increase in age, investigators found. Among people aged 65 to 69 years, for example, 3% had dementia. That figure rose to 35% for people aged 90 years and over. In contrast, rates of both conditions decreased with each additional year of education.

Disparities persist

When the data were analyzed by race and ethnic group, non-Hispanic Black participants were more likely to have dementia and Hispanic participants were more likely to have mild cognitive impairment when compared with non-Hispanic white individuals. This result was similar to the findings of other U.S. studies, the researchers reported. There were no significant differences in dementia prevalence between women and men.

These nationally representative 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,” Manly concluded.

The last such subgroup analysis from the Health and Retirement study was fielded more than 20 years ago, the authors noted. The study was published in JAMA Neurology.

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