Two new studies support the idea that regular exercise can cut the risk for subsequent cognitive decline and dementia risk.
In the first study, researchers used data from the Women's Antioxidant Cardiovascular Study (WACS), a cohort of women with prevalent vascular disease or 3 cardiovascular risk factors.
They report a significant trend toward decreasing rates of cognitive decline with increasing energy expenditure. Compared with women in the bottom forth of total physical activity, significant differences in the rates of cognitive decline were seen for those in the fourth and the fifth quintiles.
"This was equivalent to the difference in cognitive decline observed for women who were 5 to 7 years younger," the authors noted.
Specifically, regularly walking was "strongly related" to slower rates of cognitive decline. However, significant associations were seen only with the top quartile of walking, with a minimum of 30 minutes of walking daily. However, the benefit was not limited to vigorous exercise.
In a separate report, Laura E. Middleton, PhD at Sunnybrook Health Sciences Center, Toronto, Canada, and colleagues used data from the Health, Aging and Body Composition (Health ABC) Study to examine this same question. They looked at the relationship between exercise and incident cognitive impairment using activity energy expenditure (AEE), an objective measure. Physical activity questionnaires usually focus on moderate or vigorous activity related to exercise but don't capture other aspects of activity, such as moving around the house or even fidgeting, the authors note.
The authors report that after adjustment for baseline mental status scores and a variety of other factors, adults in the highest sex-specific third of AEE had lower odds of incident cognitive impairment than those in the lowest third.
In an interview, Dr. Middleton pointed out that there are now a number of studies that have confirmed this relationship, but the vast majority of those have used self-report of physical activity, an approach that carries inherent errors. Those with preclinical dementia may have issues with accurately recalling exercise, for example, and even those who have no such problems tend to over report how much they exercise.
The other issue with self-report is that it doesn't capture activity that is not actual exercise, such as housework, "and in older adults that type of activity makes up a fairly large portion of your total physical activity, especially in someone who doesn't do purposeful exercise." When they did this comparison using only self-report, there was still a relationship, she notes, but it was much clearer using the objective evidence of total energy expenditure.
Bottom line? Keep moving.