(Reuters Health) - Being physically active may offset some of the effects of brain aging on seniors’ ability to walk and control their movements, according to a new study.
At the highest level of activity, even when a specific sign of brain aging was present, it did not predict a person’s motor abilities, researchers found.
This may partly explain why older people who are more active tend to have better motor function, the authors write in the journal Neurology.
“The association between physical activity and motor function in older adults is well-established,” said lead author Debra A. Fleischman of Rush University Medical Center in Chicago. “What is less understood is the biological basis of that association.”
Older people often have the small white spots known as white matter hyperintensities (WMH) on magnetic resonance images (MRI) of their brains. An increased number of these spots has been linked to movement difficulty, such as trouble walking.
In the new study, the researchers used data from an ongoing study of aging, focusing on 167 people 60 to 96 years old without dementia. The participants had all worn activity monitors for up to 11 full days.
They also underwent MRI brain imaging and 11 motor performance tests, measuring grip strength, pinch strength, finger tapping as well as tests of lower body function.
Based on their own reports, the study participants were physically active for an average of four hours per week.
People with more white matter hyperintensities on their MRI scans tended to have poorer motor function, and those who were more active each day tended to have better motor function, but total daily activity was not related to the number of brain spots, the authors write.
With statistical modeling, they found that as activity level increased, the number of white matter hyperintensities became less important for predicting motor function.
For participants in the 90th percentile of daily activity, who walked an extra one and a half hours each day, there was no association between hyperintensities and motor function. But for those at the 50th percentile there was an association – more hyperintensities were tied to poorer function.
“What was notable was that WMHs had no effect on motor function for the persons at the highest percentile of physical activity, whereas they did affect motor function for those at the 50th percentile and the effect was even stronger for the persons at the 10th percentile of activity,” Fleischman told Reuters Health by email.
White matter hyperintensities are common for older people and have been linked to cognitive impairment, stroke and death as well as motor function, she said.
Exercise did not seem to protect against these spots, but did appear to somehow circumvent their effect on motor function. But this study only looked at people at one point in time, so it does not indicate that one factor, like exercise, caused another factor, like better motor function, she noted.
Still, the findings held when she and her coauthors accounted for other possible influences like weight, depressive symptoms, vascular disease, functional status and pulmonary function.
“To determine whether physical activity is causally related to improved mobility would require a randomized study,” according to Dr. Richard Camicioli of the University of Alberta in Edmonton, Canada, and Joe Verghese of Albert Einstein College of Medicine in New York City.
In an accompanying editorial, they write that it is difficult to tell from this study which aspects of daily activity might have been protective. The nature of physical activity, its complexity and frequency may all be important.
“I think that the important message, and the one that I give to my patients, is that they do not have to be marathon runners to maintain cognitive and motor function through physical activity as they age,” Fleischman said.
Just keep moving in any way that is safe that you enjoy, she said.
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