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.