By Judith
Graham MAY 24, 2018
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.
Langa’s research shows
that the prevalence of dementia has fallen in the U.S. — a trend observed in
developed countries across the globe. A new study from
researchers at the Rand Corp. and the National Bureau of Economic Research
finds that 10.5 percent of U.S. adults age 65 and older had dementia in 2012,
compared with 12 percent in 2000.
Because
the population of older adults is expanding, the number of people affected by
dementia is increasing nonetheless: an estimated 4.5 million in 2012, compared
with 4.1 million in 2000.
More
years of education, which is associated with better physical and brain health,
appears to be contributing to this phenomenon.
But
gains are unequally distributed. Notably, college graduates can expect to spend
more than 80 percent of their lifetime after age 65 with good cognition,
according to a new study from
researchers at the University of Southern California and the University of
Texas at Austin. For people who didn’t complete high school, that drops to less
than 50 percent.
This research looks at the older population as a whole and can’t
predict what will happen to any given individual. Still, it’s helpful in
getting a general sense of what people can expect.
An expanding period of good brain health. With longer lives and lower rates of dementia, most seniors are enjoying more years of life with good cognition — a welcome trend.
Two
years ago, Eileen Crimmins, AARP chair of gerontology at the University of
Southern California’s Leonard Davis School of Gerontology, and colleagues
documented this shift in the United States in
research using data about adults 65 and older from the Health
and Retirement Study.
In
2000, she found, a 65-year-old woman could expect to live 12.5 years with good
cognition, four years with mild cognitive impairment and 2.6 years with
dementia, on average. A decade later, in 2010, the period in good cognition had
expanded to 14.1 years, with 3.9 years spent with mild cognitive impairment and
2.3 years spent with dementia.
For
men, the 2010 figures are different: 12.5 years with good cognition after age
65 (compared with 10.7 in 2000); 3.7 years with mild cognitive impairment (the
same as in 2000); and 1.4 years with dementia (compared with 1.8 years in
2010).
Improvements
in education and nutrition, better control of hypertension and cholesterol,
cognitively demanding jobs in middle age, and social engagement in later life
may all contribute to this expanded period of good brain health, the study
noted.
Well-being
often coexists with impairment. Bardo’s research
adds another dimension to this literature by addressing two questions: Do older
adults with cognitive impairment feel they have a good quality of life and, if
so, for how long?
His
study, which has not yet been published, focuses on happiness as an important
indicator of quality of life. The data come from thousands of adults 65 and
older who participated in the Health and Retirement Study between 1998 and 2012
and who were asked if they were happy “all/most of the time” or “some/none of
the time” during the past week.
These
answers were combined with information about cognitive impairment derived from
tests that examined seniors’ ability to recall words and to count backward,
among other tasks.
Findings
suggest that cognitive impairment is not a deterrent to happiness. Of the
period that seniors spent cognitively impaired, about 5.5 years on average,
they reported being happy for 4.8 years — about 85 percent of the time. Of the
12.5 years that older adults spent in good cognitive health, they reported
being happy nearly 90 percent of the time.
The
bottom line: “Cognitive impairment doesn’t equate with unhappiness,” Bardo
said. Still, he cautioned that his study didn’t look at how happiness
correlates with the extent of impairment. Certainly, people with moderate to
severe dementia experience serious difficulties in their lives, as do their
caregivers, he noted.
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
Judith Graham: @judith_graham
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