An estimated 5 million Americans aged 65 and older have Alzheimer’s disease. As drug companies struggle to find a cure, new research from the National Runners’ and Walkers’ Health Study suggests that exercise earlier in life may substantially reduce Alzheimer’s disease mortality. The study, which appeared in an online prepublication from the Journal of Alzheimer’s Disease, involved over 154,000 runners and walkers who were followed for 11.6 years. There were 175 deaths where Alzheimer’s disease was diagnosed as an underlying or contributing cause of death during follow-up.

The amount of exercise required for protection was greater than that currently recommended by the Center for Disease Control (CDC) and various scientific organizations. They recommend a minimum of 75 minutes of vigorous exercise per week, such as running, or 150 minutes of moderate intensity exercise, such as brisk walking. These recommendations correspond to running between 4.6 and 7.7 miles per week.

Runners who ran over 15.3 miles per week, or over 2-times the recommended level, had over 40% lower risk for Alzheimer’s Disease mortality than those that were inadequately active. Running between 7.7 and 15.3 miles per week was associated with 25% lower risk compared to inadequate exercise, but this was not statistically significant. Merely meeting the CDC recommendation by running 4.6 to 7.7 miles per week was not associated with lower risk. Subjects who expended an equivalent amount of energy by walking appeared to enjoy the same risk reductions as running. However, one must walk about 50% further, and take about twice as much time walking briskly to expend the same amount of energy as running a 12-minute mile. The findings are consistent with previous research showing lower Alzheimer’s disease risk, improved cognition, and improved brain functionality and size brain morphology with exercise.

The study also looked at the effects of diet and statin drugs, both of which have been implicated in lowering Alzheimer’ disease risk. Statins are widely prescribed for lowering cholesterol, and there were 3975 subjects who used statins when they began the study. Their risk for Alzheimer’s disease mortality was 60% lower than non-users. Consumption of three or more pieces of fruit per day was associated with 60% lower Alzheimer’s disease mortality. Whether fruit directly lowered Alzheimer’s disease risk, or whether it was a marker for other foods or a Mediterranean-type diet is not known.

“Currently, doctors do not screen for Alzheimer’s disease susceptibility because of the belief that nothing can be done for those at risk. However, our results add to the growing body of scientific evidence suggesting that people can be proactive in lowering Alzheimer’s Disease risk,” said Dr. Paul Williams, the study author. The current consensus is that treatments to slow Alzheimer’s disease progression and preserve cognition are probably most effective when administered early. Presumably, this would also include exercise, diet, and statin use. The 40% to 60% risk reductions were larger than Williams expected, and additional years of follow-up are required for their precise estimation. Other health benefits of exceeding, rather than meeting, the current exercise guidelines include lower risk for hypertension, high cholesterol, diabetes, heart attacks, stroke, eye diseases, gallbladder disease, gout, various cancers, and excess body weight.

Paul T. Williams, PhD, is Staff Scientist in the Life Sciences Division at Lawrence Berkeley Laboratory. The National Runners’ and Walkers’ Health Study was funded by the National Heart, Lung, and Blood Institute, and is the only large epidemiological Study specifically created to study the health benefits of exercise. He may be reached at ptwilliams@lbl.gov. More information on his research can be found at: http://www2.lbl.gov/lsd/People_&_Organization/Scientific_Staff_Directory/Williams_Lab.html

NOTES FOR EDITORS

“Lower Risk of Alzheimer’s Disease Mortality with Exercise, Statin, and Fruit Intake,” by Paul T. Williams. Journal of Alzheimer’s Disease, November 2014, DOI 10.3233/JAD-141929. Published by IOS Press online ahead of issue. Full text of the article is available to credentialed journalists upon request. Contact Daphne Watrin, IOS Press at +31 20 688 3355 or d.watrin@iospress.nl. Journalists wishing to interview the author should contact Dr. Williams at ptwilliams@lbl.gov.