why are
DEMENTIA RATES DOWN
reported by
KHN
____________________________________________________________________
Kaiser
Health News is
an editorially independent program of the Henry J. Kaiser Family
Foundation, a nonprofit, nonpartisan health policy research and
communication organization not affiliated with Kaiser Permanente.
A new
study finds that the prevalence of dementia has fallen sharply
in recent years, most likely as a result of Americans’ rising
educational levels and better heart health, which are both closely
related to brain health.
Dementia
rates in people over age 65 fell from 11.6 percent in 2000 to
8.8 percent in 2012, a decline of 24 percent, according to a study
of more than 21,000 people across the country published Monday
in JAMA Internal Medicine.
“It’s
definitely good news,” said Dr. Kenneth Langa, a professor
of internal medicine at the University of Michigan and a coauthor
of the new study. “Even without a cure for Alzheimer’s
disease or a new medication, there are things that we can do socially
and medically and behaviourally that can significantly reduce
the risk.”
The decline
in dementia rates translates to about one million fewer Americans
suffering from the condition, said John Haaga, director of behavioural
and social research at the National Institute on Aging, part of
the National Institutes of Health, which funded the new study.
Dementia
is a general term for a loss of memory or other mental abilities
that’s severe enough to interfere with daily life. Alzheimer’s
disease, which is believed to be caused by a buildup of plaques
and tangles in the brain, is the most common type of dementia.
Vascular dementia is the second most common type of dementia and
occurs after a stroke.
The new
research confirms the results of several other studies that also
have found steady declines in dementia rates in the United States
and Europe. The new research provides some of the strongest evidence
yet for a decline in dementia rates because of its broad scope
and diverse ranges of incomes and ethnic groups, Haaga said. The
average age of participants in the study, called the Health and
Retirement Study, was 75.
The study,
which began in 1992, focuses on people over age 50, collecting
data every two years. Researchers conduct detailed interviews
with participants about their health, income, cognitive ability
and life circumstances. The interviews also include physical tests,
body measurements and blood and saliva samples.
While
advocates for people with dementia welcomed the news, they noted
that Alzheimer’s disease and other forms of memory loss
remain a serious burden for the nation and the world. Up to five
million Americans today suffer from dementia, a number that is
expected to triple by 2050, as people live longer and the elderly
population increases.
The number
of Americans over age 65 is expected to nearly double by 2050,
reaching 84 million, according to the U.S. Census. So even if
the percentage of elderly people who develop dementia is smaller
than previously estimated, the total number of Americans suffering
from the condition will continue to increase, said Keith Fargo,
director of scientific programs and outreach, medical and scientific
relations at the Alzheimer’s Association.
“Alzheimer’s
is going to remain the public health crisis of our time, even
with modestly reduced rates,” Fargo said.
Although
researchers can’t definitively explain why dementia rates
are decreasing, Langa said doctors may be doing a better job controlling
high blood pressure and diabetes, which can both boost the risk
of age-related memory problems. High blood pressure and diabetes
both increase the risk of strokes, which kill brain cells, increasing
the risk of vascular dementia.
“We’ve
been saying now for several years that what’s good for your
heart is good for your head,” Fargo said. “There are
several things you can do to reduce your risk for dementia.”
Authors
of the study found that senior citizens today are better educated
than even half a generation ago. The population studied in 2012
stayed in school 13 years, while the seniors studied in 2000 had
about 12 years of education, according to the study.
That’s
significant, because many studies have found a strong link between
higher educational levels and lower risk of disease, including
dementia, Lang said. The reasons are likely to be complex. People
with more education tend to earn more money and have better access
to health care. They’re less likely to smoke, more likely
to exercise and less likely to be overweight. People with more
education also may live in safer neighbourhoods and have less
stress.
People
who are better educated may have more intellectually stimulating
jobs and hobbies that help exercise their brains, Lang said.
It’s
also possible that people with more education can better compensate
for memory problems as they age, finding ways to work around their
impairments, according to an accompanying editorial by Ozioma
Okonkwo and Dr. Sanjay Asthana of the University of Wisconsin
School of Medicine and Public Health.
Yet Americans
shouldn’t expect dementia rates to continue falling indefinitely,
Haaga said.
Although educational levels increased sharply after the World
War II, those gains have leveled off, Haaga said. People in their
20s today are no more likely to have graduated from college compared
to people in their 60s.
“We
have widening inequality in health outcomes in the U.S.,”
Haaga said. “For people without much education, we’ve
had very little improvement in health. The benefits really have
gone to those with better educations.”
