PARIS -- Taking care of your body just might save your mind. Millions of cases of Alzheimer's disease worldwide could be prevented by curbing risk factors such as high blood pressure, smoking, obesity and lack of exercise, 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. With no cure or treatment to reverse the mind-robbing disease, preventing new cases is crucial.
The study was presented Tuesday at the Alzheimer's Association International Conference in France, where sessions on prevention have been drawing standing-room-only crowds for several days.
"Prevention is a particularly attractive option given the state of therapy. That's why there's so much interest in it," said William Thies, the association's chief scientific officer.
The study was led by Deborah Barnes, associate professor of psychiatry at the University of California, San Francisco. Results also were published online by the British journal Lancet Neurology. The researchers have grants from the Alzheimer's Association and the U.S. National Institutes on Aging.
The study used a mathematical model to estimate the impact of top modifiable risk factors for Alzheimer's disease: smoking, depression, low education, diabetes, too little exercise, and obesity and high blood pressure in mid-life.
How much of an impact each one has on total Alzheimer's cases depends on how common it is and how strongly it affects dementia risk. Researchers calculated the impact globally and just for the United States.
Worldwide, the biggest impact on Alzheimer's cases is low education, because illiteracy is so common, they found. Low education can be a sign of many factors that harm minds, such as poor nutrition. But it also is harmful by itself, because there is less opportunity to develop "brain power" that can carry you into old age.
"Education, even at a young age, starts to build your neural networks," so being deprived of it means less brain development, Barnes explained.
Smoking had the second biggest impact on cases worldwide, followed by too little exercise.
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 U.S., followed by smoking and high blood pressure in mid-life. Untreated or inadequately treated depression has long been known to raise the risk of developing Alzheimer's disease.
Reducing these seven risk factors by 25 percent could mean 3 million fewer cases of Alzheimer's worldwide, including half a million in the U.S., researchers estimated. Reducing risk factors by 10 percent would translate to 1.1 million fewer cases.
"It gives us a little bit of hope about things we could do now about the epidemic that is coming our way," Barnes said.
Alzheimer's cases are expected to triple by 2050, to around 106 million worldwide.
"We can do something about this," said Dr. Ronald Petersen, a Mayo Clinic dementia specialist who had no role in the study. A common misconception is that you're "dealt a deck of cards at birth," he said, but "people need not just sit back and watch this unfold."