Now more of us can count on more time dodging the dementia bullet

You've turned 65 and exited middle age. What are the chances you'll develop cognitive impairment or dementia in the years ahead?

New research about "cognitive life expectancy" — how long older adults live with good versus declining brain health — shows that after age 65 men and women spend more than a dozen years in good cognitive health, on average. And, over the past decade, that time span has been expanding.

By contrast, cognitive challenges arise in a more compressed time frame in later life, with mild cognitive impairment (problems with memory, decision-making or thinking skills) lasting about four years, on average, and dementia (Alzheimer's disease or other related conditions) occurring over 1½ to two years.

Even when these conditions surface, many seniors retain an overall sense of well-being, according to new research presented last month at the Population Association of America's annual meeting.

"The majority of cognitively impaired years are happy ones, not unhappy ones," said Anthony Bardo, a co-author of that study and assistant professor of sociology at the University of Kentucky-Lexington.

Recent research finds that:

Most seniors don't have cognitive impairment or dementia. Of Americans 65 and older, about 20 to 25 percent have mild cognitive impairment while about 10 percent have dementia, according to Dr. Kenneth Langa, an expert in the demography of aging and a professor of medicine at the University of Michigan. Risks rise with advanced age, and the portion of the population affected is significantly higher for people over 85.

Amal Harrati, an instructor at Stanford University Medical School, said Bardo's paper appears sound, methodologically, but wondered whether older adults with cognitive impairment can be trusted to report reliably on their happiness.

Langa of the University of Michigan said the findings "fit my general experience and sense of treating older patients in my clinical work." In the early stages of cognitive impairment, people often start focusing on enjoying family and being in the "here-and-now" while paying less attention to "small frustrations that can get us down in our daily lives," he wrote in an email response to questions.

"As cognitive decline worsens, I think it is more likely that one can become unhappy, possibly due to the advancing pathology that can affect specific brain regions" and behavioral issues such as hallucinations and paranoia, he added.

Jennifer Ailshire, an assistant professor of gerontology and sociology at USC's Leonard Davis School of Gerontology, noted that happiness is often tied to an individual's personality characteristics. This measure "doesn't necessarily reflect how individuals with cognitive impairment are interacting with other people or their environment," she commented.

Laura Gitlin, dean of the college of nursing and health professions at Drexel University in Philadelphia, observed that happiness is only one element of living well with cognitive impairment and dementia. Going forward, she suggested, "there is much work to do" to identify what contributes more broadly to well-being and a positive quality of life in older adults with these conditions.

KHN's coverage of these topics is supported by John A. Hartford Foundation, Gordon and Betty Moore Foundation and The SCAN Foundation