Elderly men who are sedentary or walk less than a quarter of a mile per day are nearly twice as likely to develop dementia and Alzheimer's disease compared to men who walk more than two miles per day, according to a study of over 2,200 Japanese-American men in Hawaii.
The study is published in the Sept. 22 issue of the Journal of the American Medical Association.
" This is additional evidence that exercise includes health benefits other than just lowering the risk for coronary disease, cancer and other diseases. We now have evidence that regular walking is also associated with benefits that are related to cognitive function later in life," said Robert D. Abbott, Ph.D., professor of biostatistics at the University of Virginia Health System and a co-author of the study.
Dementia is a chronic, or persistent, disorder of mental processes due to brain disease.
Symptoms may include personality changes, as well as losses in reasoning, orientation, and memory, that interfere with a person's usual activities.
So far, it is not clear why walking seems to protect the aging brain from dementia and Alzheimer's disease.
"If you've been active throughout your life it could have direct relationships with the same kind of healthy risk factors that are often associated with less obesity, diabetes and heart disease," Abbott said. "People who are active tend to adhere to a healthier life-style and a better diet than those who are inactive. All of these factors could be working together in determining overall vitality and how healthy our brain is. There is also the possibility that people who walk are less likely to get diseases later on in life that could lead to dementia versus people who are inactive."
The study was comprised of 2,257 physically-capable, nonsmoking Japanese-American men between the ages of 71 and 93 who were already participating in the Honolulu-Asia Aging Study, launched in the early 1990's as part of the Honolulu Heart Study.