Millions of cases of Alzheimer's disease could be prevented if more people exercised, got help for depression, quit smoking and ate properly, new research suggests.
The study offers more than the usual pep talk about healthy living. Seven conditions or behaviors account for up to half of the 35 million cases of Alzheimer's around the world, it found.
Reducing these seven risk factors by 25 percent could mean 3 million fewer cases of Alzheimer's worldwide, including half a million in the United States, researchers estimated.
The study, presented Tuesday at the Alzheimer's Association International Conference in France, was led by Deborah Barnes, associate professor of psychiatry at the University of California, San Francisco, with grants from the Alzheimer's Association and the U.S. National Institutes on Aging.
It used a mathematical model to estimate the impact of the top modifiable risk factors: smoking, depression, low education, diabetes, too little exercise, and obesity and high blood pressure in midlife.
Worldwide, the biggest impact on Alzheimer's cases is low education, because illiteracy is so common.
In the United States, however, inactivity is the leading problem because a third of the population is sedentary, Barnes said.
Depression made the next biggest impact on Alzheimer's cases in the United States, followed by smoking and high blood pressure in midlife. Untreated or inadequately treated depression has long been known to raise the risk of developing Alzheimer's disease.