Most people with aging friends and family know at least one person with dementia. Indeed, as average life expectancy rises, the number of people with dementia is soaring. But a study in the New England Journal of Medicine in February 2016 “offers cautious hope” that age-adjusted dementia rates may actually be declining. In recent years some other studies, here and in Europe, have produced similar findings, but this new research presents the most robust evidence yet.
The study, part of the well-known Framingham Heart Study, tracked 5,200 people ages 60 or older since 1975, during which time 371 of them developed dementia. It found that age-adjusted rates of dementia dropped an average of 20 percent per decade. Over the entire period, the rate dropped from 3.6 per 100 people during the first decade to 2.2 per 100 by the start of the fourth decade—a 44 percent cumulative decline. And when people did develop dementia, they did so at an older age—rising from an average age of 80 in the earliest decade to 85 by the end of the study.
Why dementia rates have declined
The improvements were driven by declines in vascular dementia (resulting from strokes and mini-strokes, for instance), not Alzheimer’s disease. The researchers linked this to dramatic improvements in cardiovascular health and cardiovascular risk factors—notably control of elevated blood pressure and cholesterol—and more effective treatment of strokes and heart disease. Indeed, much evidence indicates that what’s good for the cardiovascular system is also good for the brain.
Reasons for caution
One dark spot: People who didn’t graduate from high school did not experience a decline in dementia rates, probably in part because they did not have improvements in cardiovascular health. Better education (along with increased wealth) plays a role in the control of risk factors for both cardiovascular disease and dementia.
Other potential dark spots: Declining dementia rates may halt or even be reversed because of ongoing increases in two major cardiovascular risk factors—obesity and diabetes. And assuming that age-adjusted dementia rates do continue to decline, if average life expectancy continues to rise and the population grows, there will still be more cases of dementia, though at older ages. “The worldwide burden of dementia will continue to increase rapidly,” the researchers concluded, but “prevention might be key to diminishing the magnitude of this expected increase.”
Fighting Dementia: Yes We Can
We urgently need to find better societal solutions for managing the enormous toll of dementia while we await effective medical treatments and means of prevention—and John Swartzberg, MD, believes we can.
Also see Can Diet Prevent Dementia?