Two new studies add to the evidence that staying physically active helps protect your brain-and fill in some gaps in that research. Previous studies linking activity to reduced risk of cognitive decline have generally focused on healthy people and relied on self-reports of exercise. But these new findings address those issues and strengthen the link between physical and mental fitness.
What may be happening here, says Irwin H. Rosenberg, MD, editor of the Tufts Health & Nutrition Letter, is that exercise has an effect on improving blood flow to the brain, just as exercise improves the blood flow to your organs and muscles. Thats still conjecture at this point, however.
Both studies were published online in the Archives of Internal Medicine and simultaneously reported at the Alzheimers Association International Conference on Alzheimers Disease.
One study addressed the question of whether exercise benefits the brains of people who already have cardiovascular health problems. Marie-Nol Vercambre, PhD, from the Foundation of Public Health, Mutuelle Generale de lEducation Nationale in Paris, and colleagues at Brigham and Womens Hospital in Boston, examined data from the Womens Antioxidant Cardiovascular Study. The 2,809 participating women, average age about 73, were health professionals who had either prevalent vascular disease or three or more coronary risk factors.
The researchers determined patients physical activity levels at baseline (1995 to 1996) and every two years thereafter. Between 1998 and 2000, they conducted telephone interviews to test cognition, verbal fluency and memory. They followed up the tests three more times over the succeeding 5.4 years.
The researchers analyzed the data to link cognitive score changes with total physical activity and energy expenditure from walking. The equivalent of a daily brisk 30-minute walk, they concluded, was associated with lower risk of cognitive impairment. As activity levels increased, the rate of cognitive decline decreased.
In the second study, Laura E. Middleton, PhD, from the Heart and Stroke Foundation Centre for Stroke Recovery at Sunnybrook Research Institute in Toronto, and colleagues utilized data from the ongoing Health, Aging and Body Composition study. The subset of 197 participants, average age 74.8, had no mobility or cognitive problems when the research began.
The study tackled the self-reporting problem by measuring metabolic activity via how much water a person loses. That enabled researchers to calculate average energy expenditure (AEE) for each participant at the studys start. Middleton and colleagues also assessed cognitive function using a standard test at baseline and two and five years later.
After five years, participants who had the highest initial AEE scores-that is, who were most physically active-tended to have lower odds of developing cognitive impairment. Overall, as activity scores went up, the incidence of cognitive impairment went down. The results were adjusted for baseline cognitive scores, demographics, body mass minus fat, sleep duration, self-reported health and diabetes.
Middleton and colleagues conclude, We are optimistic that even low-intensity activity of daily living may be protective against incident cognitive impairment.
In an accompanying commentary, Eric B. Larson, MD, MPH, from Group Health Research Institute in Seattle, notes that these studies serve to buttress growing evidence that habitual physical activity and fitness are associated with age-related changes in cognition and risk of dementia. Such findings, he adds, highlight a gradual but steady change in current thinking about risk factors for late-life dementias.
Vascular risk factors such as limited physical activity may be modifiable and represent a way to reduce the incidence of cognitive impairment among older adults. Physical activity, such research suggests, could be one such avenue.
I believe that these findings can inform practice and the advice that we give our aging patients, Dr. Larson comments. We can tell them that ongoing maintenance of physical activity is definitely worthwhile and likely of increasing benefit as they advance into old age.
TO LEARN MORE: Archives of Internal Medicine, July 25, 2011; abstracts at archinte.ama-assn.org/cgi/content/abstract/171/14/1244 and archinte.ama-assn.org/cgi/content/abstract/171/14/1251. Alzheimers Association, www.alz.org, 24-hour helpline (800) 272-3900.