By Amy Norton
FRIDAY, July 24, 2015 (HealthDay News) -- New research suggests that people born after 1930 may have a lower risk of developing dementia than the generation before them, adding to evidence that the incidence of dementia may be declining in the United States and elsewhere.
That decline was not explained by age, but did seem to be related to improvements in heart health over time, the researchers found.
The study, of nearly 1,000 elderly New Yorkers, found that those born after 1930 had a lower risk of dementia than those born between 1916 and 1930.
In the older group, people developed dementia at a rate of 2.2 percent per year between 1993 and 2014, when they were in their 70s and beyond, said lead researcher Carol Derby, an associate professor of neurology at the Albert Einstein College of Medicine, in New York City.
In the younger group, that rate was just over 0.4 percent per year, Derby added.
"We did see the same [declining] trend in cardiovascular disease, and that may explain part of the decrease we found in dementia," said Derby, who presented the findings this week at the Alzheimer's Association International Conference, in Washington, D.C.
The pattern confirms what's been seen in other studies from the United States, the United Kingdom, Sweden and other countries, according to Maria Carrillo, chief science officer for the Alzheimer's Association.
Overall, older people in developed countries do seem to be developing dementia at a lower rate. And improvements in heart health -- including better management of high blood pressure and heart disease -- do appear to be a big part of it, according to Carrillo.
"We know that what's good for your heart is good for your brain," Carrillo said.
Regular exercise, not smoking, eating a healthy diet and maintaining a normal weight can all help ward off heart disease and stroke -- and possibly stave off dementia, too, Carrillo explained.
However, she added, heart health is only part of the story when it comes to dementia. Studies have shown that education, and staying mentally active over a lifetime, may help protect against dementia. It's thought that such mental engagement can make the brain more resistant to the buildup of "plaques" and other tissue damage that marks Alzheimer's and other forms of dementia.
"We know that in certain populations, educational attainment has gone up over the years," Carrillo said.
Still, despite the "good news" from this study, Carrillo and Derby both stressed that the battle against dementia isn't over.
For one, the prevalence of dementia -- the total number of people affected -- is large and growing, due to the aging of the baby boomer population.
According to the Alzheimer's Association, over 5 million Americans currently have Alzheimer's disease, the most common form of dementia. That number could nearly triple by 2050, to 14 million, the group estimates.
If the rate of dementia keeps dipping, it's possible that the prevalence won't soar as high as that, Derby said.
Carrillo agreed that those patterns are worrisome, since they could reverse some of the gains that have been made in heart health.
"And a big concern in the U.S.," Carrillo added, "is that the population is broad and diverse. There are still disparities in educational attainment, and access to health care."
According to Derby, the new findings underscore a positive message: There are ways to reduce the likelihood of dementia, or stall its onset. At the same time, she said, researchers need to learn more about the protective factors.
"These findings are encouraging," Carrillo said. "But this does not mean our work is done."
The data and conclusions of research presented at medical meetings should be viewed as preliminary until published in a peer-reviewed journal.