The rate of dementia among Americans aged 65 and older appears to be on the decline, even though more American men and women are living longer, a USC-led team of researchers has found.
Also in their analysis, the researchers found that the length of life with dementia and cognitive impairment was slightly shortened for men and women aged 65 and over.
“This indicates aging men and women are living a longer healthy life and a shorter impaired life,” said University Professor Eileen Crimmins, AARP Professor of Gerontology at the USC Leonard Davis School of Gerontology. “This is something we have not seen before in terms of most other diseases and conditions.”
The rate of dementia dropped significantly for Americans 65 and older: Dementia decreased by 2.6 percent from 7.72 percent among men and declined 1.99 percent from 10.8 percent among women.
The researchers also found that more Americans 65 and older have their memories intact. The prevalence of having no cognitive problems increased by 4.45 percent for men and 3.41 percent for women.
The findings offer some good news for families and their aging loved ones.
“It is reassuring to people to think that longer life can be lived without cognitive loss and will reduce the use of resources for caring for people with loss,” said Crimmins, a co-investigator of the U.S. Health and Retirement Survey and director of the USC/UCLA Center on Biodemography and Population Health that is supported by the National Institute on Aging.
She presented her team’s preliminary findings at the annual meeting of the American Association for the Advancement of Science in Washington, D.C., on Feb. 13.
Other key findings
The researchers also found that people are living longer with healthy memory, based on their analysis of the 2000 and 2010 U.S. Health and Retirement Survey and national vital statistics.
In the 2010 study, the life expectancy for men aged 65 with healthy memory was 17.7 years — 1.8 years longer than the men in the 2000 study. The life expectancy for women aged 65 was 20.3 years – 1.2 years longer than women in the 2000 study.
The life expectancy with healthy memory for people aged 85 also lengthened by 0.3 years for men and 0.5 years for women, the research showed.
The Health and Retirement Study of Americans 65 and older included 10,711 participants in 2000 and 10,937 participants in 2010 who reported on their cognitive states. Their cognitive statuses were determined through a series of tests for those who were self-respondents, and their cognition was rated according to a set of cognitive functioning scores and dementia diagnoses and cognitive impairment without dementia.
Other co-authors were Yasuhiko Saito, director of the Japanese Longitudinal Study of Aging at Nihon University, and Jung Ki Kim, a research assistant professor at USC Leonard Davis.
The study was funded by the National Institute on Aging.
USC researchers in multiple disciplines are dedicated to studying and solving age-related issues such as Alzheimer’s disease and dementia, as well as their health, political, economic and social implications.
Through their research, they are expanding scientific knowledge and support for the wicked problems of age-related disease and the challenges associated with an aging population.