Aerobics and the elderly: fMRI reveals benefits of staying active

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  • Published: Jun 1, 2011
  • Author: David Bradley
  • Channels: MRI Spectroscopy
thumbnail image: Aerobics and the elderly: fMRI reveals benefits of staying active

Exercise and the aging brain

Increased physical activity involving aerobic exercise might slow age-related decline according to a new functional magnetic resonance imaging (fMRI) and transcranial magnetic stimulation (TMS) study funded by the US Department of Veteran's Affairs. The study shows how the brain's motor cortex changes as we get older particularly in those people who become more sedentary as they do so. However, maintaining a physically active lifestyle can preclude the changes that lead to unnecessary decline.

Keith McGregor, Zvinka Zlatar and colleagues under the direction of Bruce Crosson at the Malcom Randall VA Medical Center and the University of Florida explain how researchers have associated aerobic exercise with amelioration of aging-related decline in humans. They point out that evidence has also indicated that chronological aging seems to be associated with a decrease in measures of interhemispheric inhibition during unimanual movements. This problem is, however, mitigated by long-term physical fitness. They have now studied a healthy, right-handed participant group consisting of twelve sedentary older adults (60 to 85 years), twelve physically active older adults, and twelve young adults (18-37 years). They hoped to provide new evidence that physical fitness acts as a buffer against cognitive and physical decline in normal aging.

Other researchers have previously used neuroimaging, particularly MRI and diffusion tensor imaging (DTI) in studies of the benefits of exercise on the human brain. Those studies have suggested that exercise increases brain volume, conserves "gray matter" density and might even contribute to an increase in density of "white matter" in the brain. fMRI studies on older volunteers carrying out mental tests have also been revealing showing that there is a link between physical fitness and brain activity; good cardiovascular fitness, it seems, helps keep your brain fit too.

Focusing on brain activity

McGregor and colleagues have focused on brain activity while the volunteers carry out a task with one hand to see whether physical fitness and age might affect the way in which the two hemispheres of the brain interact. The hypothesis being that a greater level of fitness will ensure good communication as we age, whereas as a sedentary lifestyle as one gets older would lead to losses.

The team monitored ipsilateral (right) primary motor cortex activity while volunteers moved their right hand using fMRI. They found that physically active older adults and younger adults had longer ipsilateral silent periods, in the TMS portion of the study, and less positive blood-oxygen level dependent MRI of ipsilateral motor cortex (iM1) when compared to the sedentary older adults. "These findings suggest that increased physical activity may have a role in decreasing aging-related losses of interhemispheric inhibition," the team says. "One of the strengths of this investigation is that it marks, we believe, the first study to combine both fMRI and TMS to assess the relationship between physical activity and interhemispheric inhibition in aging," they report.

While these early results are suggestive of physical activity correlating with improved brain function in older adults, the team concedes that the study tested only a small number of people and that for some of the volunteers the level of physical activity was self-reported as opposed to being based on a standard measure of fitness, such as a treadmill test of maximum oxygen uptake.

"The full implications of [the] changes [observed] need to be explored across the life span by expanding measures of motor performance and measures of fitness and by examining the rate of change in cortical and motor functions from young to old age," the researchers say. "It will also be important to understand whether the changes in motor cortical function reported in this study are unique to the motor system, or if these findings would extend to the neural substrates of perception and cognition," they conclude.

 



The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

 Aerobic exercise might slow age-related decline according to a new functional magnetic resonance imaging study of transcranial magnetic stimulation (TMS). The study shows how the brain's motor cortex changes as we get older particularly in those people who become more sedentary as they do so. However, maintaining a physically active lifestyle can preclude the changes that lead to unnecessary decline.

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