The risk of developing dementia is decreasing for people with at least a high school education, according to an important 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 to date that a more educated population and better 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 they suggest that the long-term cost of dementia care may not be as devastatingly expensive as policymakers had predicted, because more people will be able to live independently longer.
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 medical 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, the actual number 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 reported in the new study was strongest in vascular dementia, which is most directly linked to cardiovascular problems. Alzheimer's, the most common form of dementia, also declined, but the trend narrowly missed what researchers consider statistically significant.