In the study, researchers report on several recent investigations that show how age-adjusted rates in aging populations have declined for people born later in the last century, particularly in those older people most likely to develop dementia and Alzheimer’s disease.
“Of course, people are tending to live longer, with worldwide populations aging, so there are many new cases of dementia,” says Eric B. Larson, M.D., M.P.H., executive director of Group Health Research Institute.
“But some seem to be developing it at later ages—and we’re optimistic about this lengthening of the time that people can live without dementia.”
Dementia in those affected may be starting later, closer to the time of death. The researchers also report that lifestyle diseases such as diabetes, hypertension, cardiovascular disease and obesity are believed to influence the development of dementia.
In 2008, Drs. Kenneth Langa and Larson reported one of the first studies suggesting a decline in U.S. dementia rates, using information from the U.S. Health and Retirement Study.
They found that the decline tracked with education, income, and improvements in health care and lifestyle. Since then, several studies in Europe have confirmed this trend—and the reasons behind it.
“We’re very encouraged to see a growing number of studies from around the world that suggest that the risk of dementia may be falling due to rising levels of education and better prevention and treatment of key cardiovascular risk factors such as high blood pressure and cholesterol,” Langa said.
He added that it will be very important to continue to follow these trends given the wide-ranging impact of dementia on patients, families, and the health care system.
“This is a fascinating example of personal health changes earlier in life having an impact on personal and public health in late life,” said co-author Dr. Kristine Yaffe.
She and Larson have reported that regular exercise may help delay dementia.
In an earlier publication this year in the New England Journal, Larson’s team reported that people with lower blood sugar levels tend to have less risk of dementia.
And Yaffe and her team have focused on a host of other lifestyle factors that have the potential to reduce risk.
“Still, we need to be aware that recent increases in obesity and diabetes threaten to reverse these gains, because of the impact these conditions can have on the aging brain,” Yaffe said.
“The obesity and diabetes epidemics are not affecting age groups most at risk for dementia yet. But it’s just a matter of time.
“To help more people avoid dementia, we’ll need to find better ways of preventing obesity — and avoiding obesity-linked health risks, including diabetes and dementia,” Larson said.
Narrowing health disparities will also be crucial, because obesity and diabetes are more common among certain racial and ethnic minorities and others who lack access to education and health care.
“As luck would have it, preventing obesity and diabetes jibes with preventing dementia,” Larson said. “In other words, we must focus on exercise, diet, education, treating hypertension, and quitting smoking.”
On December 11, the New England Journal of Medicine will post a podcast of Larson discussing this perspective piece, and that day he and Yaffe will also address the U.K. Department of Health’s G8 Dementia Summit in London. The summit aims to develop coordinated global action on dementia.
Source: Group Health Research Institute