One in 10 older Americans has dementia, and twice as many have mild mental impairment, a new study finds.
As the nation's population grows older, the burden on families and society is likely to grow, and minorities will be affected most, experts say.
"As the population in the U.S. ages, it is projected that there will be more cases of cognitive impairment, unless and until effective prevention strategies are developed and implemented," said Percy Griffin, director of scientific engagement at the Alzheimer's Association.
The main findings of this study are that 10% of people 65 and older in the United States have dementia, and about 22% have mild cognitive impairment, which is a state between normal cognitive function and dementia, said co-author Dr. Kenneth Langa, a professor of medicine at the University of Michigan.
Those afflicted are more likely to have lower levels of education and to be Black or Hispanic, the researchers found.
The reasons? Lack of access to care and stress brought on by discrimination -- the plight of being Black or Hispanic, Langa said. Also, less education and poverty make these people at higher risk for dementia and mild cognitive impairment, he added.
"Those are sort of key lifelong influences we think probably put African American and Hispanic individuals at higher risk," Langa explained.
More education leads to using your brain more, which might be how education can help stave off dementia and mild cognitive impairment, he said.
"Basically, they're able to compensate for the changes in the brain that happened with aging that lead to cognitive decline," Langa said, referring to older, better educated adults. "So people with higher levels of education can sort of compensate for the problems that build up in the brain, the pathologies that build up in the brain, and can remain thinking normally longer than others with lower levels of education."
For the study, the researchers collected data on 3,500 U.S. men and women who took part in the Health and Retirement Study. Between 2016 and 2017, participants underwent neuropsychological tests and interviews, which were used to determine dementia or mild cognitive impairment.
Rates of dementia and mild cognitive impairment jumped with age, starting with 3% of people between 65 and 69, rising to 35% for those 90 and over, the research team found.
Among older Black Americans, 15% suffer from dementia and 22% from mild cognitive impairment. Among Hispanic men and women, 10% have dementia and 28% have mild cognitive impairment. For white Americans, it's 11% and 23%, the researchers found.
Among those with less than a high school education, 13% suffer from dementia and 30% from mild cognitive impairment. But for those with a college degree or advanced degree, the rates drop to 9% and 21%.
In economic terms, dementia -- including unpaid family caregiving -- costs an estimated $257 billion a year in the United States and $800 billion worldwide, the researchers said in background notes.
These data are from 2016, Langa said. With so many older Americans dying from COVID-19, it's possible the rates for dementia and mild cognitive impairment might be a little lower in 2022. But it's also possible that the long-term effects of the virus will increase cases of dementia and mild cognitive impairment, he said.
Griffin, who played no role in the study, isn't optimistic.
"With increasing longevity and the aging of the baby boomer generation, the number of people with cognitive impairment and dementia -- and thus the burden on the nation, communities and families -- is expected to increase in the decades ahead," he said.
With 12% to 18% of people age 60 or older living with mild cognitive impairment, these numbers highlight the need to raise awareness and to better prepare physicians to identify and manage patients with cognitive impairment, Griffin said. "Early intervention offers the best opportunity for better outcomes," he noted.
Rising rates of obesity and diabetes, which are risk factors for dementia, could also spawn an uptick in dementia trends in the coming decades, he said.
Several lifestyle factors influence your risk of developing dementia, Griffin said. "There is a substantial body of evidence that what is good for the heart is good for the brain. For example, intensive treatment to reduce blood pressure can significantly reduce the occurrence of mild cognitive impairment," he said.
Regular exercise and eating a heart-healthy diet may also reduce a person's risk of cognitive decline and possibly dementia, Griffin said. "It's never too early nor too late to address your risk for dementia," he said.
Or as Langa tells his patients: "Walk, talk and read."
The report was published online Oct. 24 in JAMA Neurology.
The American Psychological Association talks about the signs of mild cognitive impairment.
SOURCES: Kenneth Langa, MD, PhD, professor, medicine, University of Michigan, Ann Arbor; Percy Griffin, PhD, director, scientific engagement, Alzheimer's Association; JAMA Neurology, Oct. 24, 2022, online