Thursday, Feb. 11, 2016 | 12:47 a.m.
The risk of developing dementia is decreasing for people with at least a high school education, says a new study that suggests that changes in lifestyle and improvements in physical health can help prevent or delay cognitive decline.
The study, published Wednesday in The New England Journal of Medicine, provides the strongest evidence yet that better education and cardiovascular health are contributing to a decline in new dementia cases over time, or at least helping more people stave off dementia for longer.
The findings have implications for health policy and research funding and suggest that long-term costs of dementia may not be as devastatingly expensive as predicted.
There are wild cards that could dampen some of the optimism. The study participants were largely white and suburban, so results may not apply to all races and ethnicities. Still, a recent study showed a similar trend among African-Americans in Indianapolis, finding that new cases of dementia declined from 1992 to 2001. The 2001 participants had more education, and although they had more cardiovascular problems than the 1992 participants, those problems were receiving more treatment.
Another question mark is whether obesity and diabetes, which increase dementia risk, will cause a surge in dementia cases when the large number of overweight or diabetic 40- and 50-year-olds become old enough to develop dementia.
In any event, in the next few decades, actual numbers of dementia patients will increase because baby boomers are aging and living longer.
“You don’t want to give the impression that the Alzheimer’s or dementia problem is disappearing — it’s not at all,” said Dallas Anderson, a program director on dementia at the National Institute on Aging, one of two agencies that financed the study. “The numbers are still going up because of the aging population.”
Still, he added, the new research shows that “what happens in a person’s life becomes important.”
“It’s not just, ‘Oh, it’s in your genes. You’re going to get it,’” he said. “You can take steps to postpone the disease.”
The decline in the new study was strongest in vascular dementia, which is most directly linked to cardiovascular problems. Alzheimer’s, the most common dementia, also declined, but the trend missed what researchers consider statistically significant.
Still, Maria Carrillo, chief science officer for the Alzheimer’s Association, an advocacy group and research funder, said “this tells me there absolutely is hope for Alzheimer’s” if a push for healthier lifestyles accompanies efforts to find dementia treatments.
Dementia experts and advocacy groups have predicted that the number of Americans with dementia, now about 5 million, will triple by 2050. But a burst of research in Europe, Canada and the United States show recent decreases in dementia among better-educated populations with better-controlled cholesterol, blood pressure, and heart and lung health.
“There’s more studies suggesting that the risk is going down and we might have to rethink some of the projections of how big a problem dementia will be 30 years from now,” said Dr. Kenneth Langa, a professor of internal medicine at the University of Michigan. On Saturday, he will present at an international conference preliminary results from another large study, which found that the prevalence of dementia in a more nationally diverse population declined by about 21 percent from 2000 to 2010.
Results like this suggest, he said, “that even without a big breakthrough in medication or a vaccine that would stop the Alzheimer’s process, that we can do things that lower the risk of dementia long term.”
The New England Journal research is considered especially strong because it looked at the emergence of new dementia cases, or incidence, and used data from the Framingham Heart Study, a large collection of health information that began in 1948 with participants from Framingham, Massachusetts, and continues to follow them and their descendants.
Researchers evaluated cognitive status in 5,025 people aged 60 and older in four time periods beginning in 1977 and found a steady decline of about 20 percent in new dementia cases each decade. They also found that the average age of developing dementia increased, from 80 in the 1970s, to 85 four decades later.
Significantly, the decline in new dementia cases, or incidence, occurred only with people who had at least a high school diploma. High school graduates were also the only ones whose cardiovascular health, except for obesity and diabetes, improved steadily over the same 40 years.
“Whether education is beneficial in itself or whether education is a marker for other things like poverty and unhealthy lifestyle, we didn’t parse that out,” said Dr. Sudha Seshadri, a neurologist at Boston University Medical Center and a senior investigator with the Framingham Heart Study.
She said researchers did not find that college-educated people had even lower dementia risk, but with few college graduates in the study’s early groups, it was hard to tell. The study led by Langa, which compared a nationally representative survey of about 10,000 Americans aged 65 and over in 2000 with a similar group in 2010, found more college correlated with less dementia.
“We find the more education the better,” said Langa, whose study indicated that people in 2010 averaged almost a year more education than those in 2000, and that education explained about half the decline in dementia.
Education may help delay dementia because it improves economic opportunity, which propels healthier habits and medical care access. Another theory is that learning generates more neural connections, allowing brains to compensate longer when memory and thinking falter.
“That’s a major puzzle: What is the causal effect of education on dementia and cognitive function later in life?” said Michael D. Hurd, the director of the RAND Center for the Study of Aging.
Hurd, who led a 2013 study estimating that dementia costs would more than double by 2040, said it was too early to say if that estimate should be lowered. Some people will live longer with dementia, needing more years in nursing homes, he said, adding that “Framingham is not the U.S. population.”
Indeed, another study published Wednesday found significant racial disparities, with African-Americans most likely to develop dementia, Asian-Americans the least likely, and whites and Latinos in between.
Not all the Framingham results are explained by education or cardiovascular health, Seshadri said, reflecting dementia’s complexity.
Marie and Joe Porcello, study participants, are 86-year-old high school graduates with no significant cardiovascular problems or family history of dementia. But Joe Porcello remains healthy, while his wife, a retired secretary, developed dementia about 10 years ago and is in an assisted-living facility.
“I took care of her as long as I can, and then she fell one day when she was getting out of the bathtub,” Joe Porcello said. He said she usually recognized him, but recently, “she said, ‘Who are you?’ and I said ‘I’m your husband.’ Then right away she knew who I was and she puckered up like she wanted to give me a kiss.”
Joe Porcello, a retired phone company foreman, attended night school for postsecondary algebra classes, but “in my lifetime, you didn’t really have to go to college,” he said.
“Today, everybody has to go to college, or you end up pushing carts in supermarkets.”
Their daughter Cynthia Johnson, 54, a former software engineer with a bachelor’s degree, belongs to a generation that researchers would now predict to have less dementia.
But David Jones, a professor of the culture of medicine at Harvard, said disease trends were rarely straightforward. Dementia, he said, “won’t be as bad as it would have been had incidence not begun to fall, but it will still be a very difficult problem.”