Up to half of Alzheimer's disease cases worldwide are potentially attributable to seven preventable risk factors, a new study suggests.
The findings show that Alzheimer's cases could be reduced if people quit smoking, increased their physical activity, enhanced their mental activity, controlled their blood pressure and diabetes, and managed their obesity and depression.
The top 3 factors
In this study by University of California, San Fransisco, the authors reviewed previous research that examined factors that predispose people to developing Alzheimer's. They identified seven factors that were potentially within a person's control to change.
Enhancing mental activity could make the biggest difference in developing Alzheimer's. That's because the study showed "low educational attainment" was the factor that impacts the largest portion of Alzheimer's cases worldwide. They defined low educational attainment as not completing higher education, having a low IQ or not participating in mentally stimulating leisure time activities, and found it contributes to 19% of Alzheimer's cases, or 6.5 million cases worldwide.
Smoking contributes to the second-highest number of cases, 14% of cases, or 4.7 million cases worldwide.
Physical inactivity contributed to 13% of worldwide cases and was the third-largest factor. However, it was the highest contributor to cases in the U.S. — contributing to 21%, or 1.1 million cases.
What really mattered was how common the risk factors were in the population. In the U.S., about a third of the population is sedentary, so a large number of Alzheimer's cases are potentially attributable to physical inactivity.
However, worldwide, low education was more important, because so many people throughout the world are illiterate or are not educated beyond elementary school. And, smoking also contributed to a large percentage of cases worldwide because it is still very common.
This suggests that smoking cessation and initiatives to increase physical activity could dramatically decrease the number of Alzheimer's cases.
A note of caution
It has been noted that while these seven factors may contribute to the development of Alzheimer's, none of the factors have been shown to cause the disease.
However, the findings suggest "that preventive and therapeutic interventions have great potential," and that interventions should be carried out in high-risk populations.
Globally, an estimated 33.9 million people have Alzheimer's, but that number could be reduced by 3 million if there was a 25% reduction in all seven of these risk factors. A 10% reduction in these seven factors could prevent 1.1 million cases. The number of worldwide cases is expected to triple over the next 40 years.
The results of the study were presented July 20 at The Alzheimer's Association 2011 International Conference on Alzheimer's Disease (ICAD), held in Paris. The study was simultaneously published online in the journal The Lancet Neurology.
Original article on MSNBC.com