(Ivanhoe Newswire) -- Can you prevent Alzheimer's disease? New research shows up to half of all Alzheimer's cases are attributable to seven preventable risk factors.

About 33.9 million people have Alzheimer's disease worldwide, and researchers expect that number to triple in the next 40 years.

In the new study, presented at the Alzheimer's Association 2011 International Conference in Paris, researchers reviewed data related to predisposing factors for Alzheimer's. They identified seven risk factors: low educational attainment, smoking, physical inactivity, depression, midlife obesity, midlife high blood pressure and diabetes.

Results suggest a 25 percent reduction in all seven risk factors could prevent as many as 3 million cases of Alzheimer's disease worldwide.

The researchers found low educational attainment contributed to the largest proportion of Alzheimer's cases worldwide, and smoking contributed to the second largest proportion of cases. Physical inactivity came in third.

"What really mattered was how common the risk factors were in the population. In the USA, about a third of the population is sedentary, so a large number of Alzheimer's cases are potentially attributable to physical inactivity. Worldwide, low education was more important because so many people throughout the world are illiterate or are not educated beyond elementary school. Smoking also contributed to a large percentage of cases because it is unfortunately still really common," Deborah Barnes from the University of California, San Francisco, was quoted as saying.

These findings suggest there are ways to reduce the preventable risk factors that contribute to Alzheimer's disease.

SOURCE: The Alzheimer's Association 2011 International Conference on Alzheimer's Disease in Paris and published online in The Lancet