If you want to keep your mind sharp as you age, make sure you exercise your body regularly.
Two recent studies provide strong evidence of a correlation between exercise and better cognitive function among seniors.
A French study of 2,809 women conducted over five years confirmed that the women who got daily exercise equivalent to a brisk 30-minute walk are less likely to have cognitive impairment than the women who exercised less or not at all. The impairment means problems with memory, language, thinking and judgment.
A Canadian study of 197 seniors with an average age of 74.8 used a more precise measurement of physical activity: active energy expenditure. (AEE is defined as 90 percent of total energy expenditure, minus resting metabolic rate.) When their data were adjusted for other variables, those with the highest AEE were the least likely to suffer from cognitive impairment.
Both studies were published in the Archives of Internal Medicine in July to coincide with an international conference on Alzheimer's that was held in Paris that month.
They strengthen earlier, less well-documented studies that showed a correlation between exercise and reduced cognitive impairment, but there remains a chicken-and-egg problem, said Carol Schramke, Ph.D., director of the division of behavioral neurology at Allegheny General Hospital in Pittsburgh.
"It's hard to know when these things correlate," Schramke said. "Is it that (mentally) healthier people are more likely to exercise? Or is it that the exercise helps them remain more cognitively intact?"
Factors other than exercise may be involved, she said.
"(Studies have shown) people who did line dancing did better over time than the people who walked on a treadmill," Schramke said.
Line dancing is a social activity. Walking on a treadmill is a solitary one. Could the social activity be as important as the exercise?
Because there is "all kinds of great evidence exercise reduces the risk of cancer and heart disease," it is reasonable to assume that it also reduces cognitive impairment, Schramke said. But more study must occur before researchers can be sure exercise is not merely correlated with better cognitive function but actively causes it.