TUESDAY, July 15, 2014 (HealthDay News) -- The number of new
cases of dementia has been declining in recent decades in the
United States, Germany and other developed countries, a trio of new
In one U.S. study, researchers found that compared with the late
1970s, the rate of dementia diagnosis was 44 percent lower in
recent years. The sharpest decline was seen among people in their
A second study, which reviewed research from England, the
Netherlands, Sweden and the United States, found a similar pattern.
The third study, meanwhile, found signs of progress in the space of
only a few years: In 2004, older German adults were about
one-quarter more likely to be diagnosed with dementia than in
"This is some good news," said Dean Hartley, director of science initiatives for the nonprofit Alzheimer's Association. The three studies are being presented Tuesday at the Alzheimer's Association International Conference, in Copenhagen, Denmark. Research presented at meetings should be considered preliminary until published in a peer-reviewed journal.
"We hope this data is saying, 'There are things we can do to change this,' " Hartley added, referring to the huge human and financial toll of dementia worldwide.
In the United States alone, about 5.2 million people have
Alzheimer's disease, the most common form of dementia, according to
the Alzheimer's Association. And the cost of caring for all of them
is expected to total $214 billion this year.
Why is the rate of new dementia cases apparently dipping? Better
cardiovascular health could be one reason, said Claudia Satizabal,
a researcher at Boston University School of Medicine, who led the
Her team found that over the years, people's average blood
pressure and cholesterol levels improved, and their rates of
smoking, heart disease and stroke declined.
Hartley said that is a plausible explanation. A number of
studies have linked better cardiovascular health to a lower risk of
Alzheimer's -- possibly because a healthy heart and blood vessels
are more efficient at delivering oxygen and energy to brain
"What's good for the heart is also good for the brain," Hartley said.
Another potential factor: In general, people are better educated
now than they were decades ago, and many studies have linked higher
education levels to a lower Alzheimer's risk, or later onset of the
It's possible, according to Hartley, that education is just a
marker of some other protective factor. But he also pointed to the
"cognitive reserve" theory.
According to that theory, people who are more educated may be
able to function normally, even when the brain begins to take on
Alzheimer's-linked changes -- those abnormal protein deposits known
as "plaques" and "tangles."
Basically, their brains may be better equipped to compensate for
that damage, by recruiting alternative brain-cell networks, for
example. And, Hartley said, it's thought that the same could be
true of older people who stay mentally active -- by reading, taking
classes, playing games or socializing.
Satizabal said her study has some limitations, including the
fact that the participants were mainly white Massachusetts
residents. "We don't know if the results would be the same in
African Americans, or Asian or Hispanic Americans," she said.
And while there were positive trends in conditions like high
blood pressure and high cholesterol, the reverse was true when it
came to obesity and diabetes -- which grew more common over
The decline in dementia is "great news," Satizabal said, but it
might have been even better were it not for the rising rates of
obesity and diabetes.
"It's important to manage cardiovascular risk factors while you're young," Satizabal said. "Don't wait until you're older."
And as for the link between education and dementia, she agreed
with Hartley that mentally stimulating activities may be key. "You
don't have to have a Ph.D. to be mentally active throughout your
life," Satizabal said.
What's really needed are clinical trials that test the idea that
lifestyle choices and better cardiovascular health can stave off
dementia, Hartley noted. And those trials are already under way, he
said. A study in Finland is looking at whether diet changes,
physical and mental exercise, and social activities can forestall
dementia in older adults who have an increased risk.
The Alzheimer's Association has more on
cutting dementia risk.
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