I don't know if you remember, but we have been panicking lately about predictions that an epidemic of dementia is waiting to sweep through an aging U.S. population, bankrupting families as well as the health care system.
About 5.4 million Americans — 1 in 9 over the age of 65 — are affected by Alzheimer's (the most common form of dementia), and because we are living longer (and there are a lot of us boomers), that number was expected to double or triple by 2050, by various estimates.
And a study by the Alzheimer's Association estimates that the disease costs about $57,000 a year per patient, and most of that must be paid by the family. Because those suffering from the disease are most often over 65, its costs are likely to blow up Medicare, too.
However, it is possible we were jumping to the wrong conclusion: that the number of those affected would continue to increase as the size of the older population increases.
A couple of new studies from England and Denmark suggest that the numbers can be expected to retreat as people adopt healthier lifestyles and acquire more education.
And another study, in France, suggests that those who delay retirement — staying socially engaged and mentally sharp longer — are also at less risk of dementia. Proof that if you don't use it, you will lose it, perhaps.
There are some skeptics, of course. Maybe we need to move to France or the British Isles if we want to avoid dementia, because obesity is epidemic in this country, and the research suggested that controlling blood pressure and cholesterol — two of the casualties of unhealthy eating — were instrumental in lowering the risk by reducing the incidence of mini-strokes or vascular disease in the brain. The same kinds of studies are needed in America to test the trend, experts say.
But it seems that the assumption that each generation would be at the same risk of dementia may not hold up.
It was a study by the RAND Corporation, based on the calculation that the same percentage of the population would continue to be affected, that concluded that the number of dementia patients would double in the next 30 years as boomers aged.
However, a study of people over 65 in England and Wales, published this week in The Lancet, showed that the rates of dementia had dropped by an astonishing 25 percent over the past two decades, from 8.3 percent to 6.2 percent.
And in Denmark, people in their 90s who were given a standardized test in 2010 scored much better than those 90-year-olds who had been tested a decade ago, and the percentage of those showing signs of severe impairment dropped, too.
It may be too late for those of us who came late to the game of healthy eating, exercise and mental gymnastics as a way to keep the brain healthy, but it bodes well for future generations, who can learn from our poor example. Those principles are taking better hold among our children and their children.
Meanwhile, the French study — so credible because the French keep meticulous health records, and the sample was of more than 420,000 people — found that for each additional year of work, the risk of getting dementia was reduced by 3.2 percent. For example, someone who retired at 65 had about a 15 percent lower risk of dementia than someone who retired at 60.
This research adds credence to the new notion of retirement — one spent in a kind of second career that includes mental challenges and social engagement and physical activity.
This is heartening news because the specter of dementia is particularly harrowing. That we could, in effect, forget ourselves is a cruel last trick played by the mysterious and powerful brain.