CHAMPAIGN, Ill. - Aging adults who give up a sedentary lifestyle and replace it with a cardiovascular fitness regimen as simple as brisk walks reap greater focus and reduced decision-making conflict as they perform a variety of tasks, scientists say.
That conclusion comes from a study that utilized functional magnetic resonance imaging to measure changes in brain activity in adults ranging in age from 58 to 78 before and after a six-month program of aerobic exercise. The study, done at the University of Illinois at Urbana-Champaign, appears on line this week ahead of print publication in the Proceedings of the National Academy of Sciences.
Scientists, led by Arthur F. Kramer, a professor of psychology and researcher at the Beckman Institute for Advanced Science and Technology at Illinois, identified specific functional differences in the middle-frontal and superior parietal regions of the brain that changed with improved aerobic fitness. These changes allowed researchers to predict improvements in performance on a decision-making task.
The middle-frontal region of the brain is responsible for keeping goals of an activity in focus. The superior parietal area has been linked to many functions, including the spatial attention.
Participants of the aerobic-exercise intervention reduced their level of behavioral conflict in completing a computer-based task by 11 percent from pre-exercise levels, while the control subjects who performed stretching and toning activities achieved a statistically insignificant decrease of 2 percent.
Previously, Kramer and colleagues had documented that aging adults do better cognitively if they are physically fit and that parts of the brain in active older people contain more white and gray matter.
The new study - the first involving an exercise intervention in human subjects along with state-of-the-art neuroimaging - focused on actual changes in brain function and the capability of previously non-active aging adults to improve their ability to ignore distractions. It ties brain changes to cognitive changes, Kramer said.
"We continue to find a number of cognitive benefits in the aerobic group that are very consistent with results found in the animal literature," he said. "The brain circuits that underlie our ability to think - in this case to attend selectively to information in the environment - can change in a way that is conducive to better performance on tasks as a result of fitness. The kinds of tasks that we explored are similar to those encountered in real world situations such as driving a vehicle or any endeavor that requires a person to pay attention despite distractions."
Results of aerobic-intervention programs in rats and mice regularly show biochemical changes, particularly in the production of a molecule known as brain-derived neurotropin factor, which serves to protect the brain and increase the connections between neurons and promote neurogenesis, he said.
The new paper looked at brain function of subjects with differing fitness levels at the beginning and end of each experiment. Participants doing toning and stretching had increased activation in some areas of the brain but not in those tied to better performance.
The aerobic exercise used in the study involved gradually increasing periods of walking over three months. For the final three months of the intervention program, each subject walked briskly for 45 minutes in three sessions each week.
The National Institute on Aging and the Institute for the Study of Aging funded the study. Co-authors were postdoctoral researcher Stanley J. Colcombe; Edward McAuley, professor of kinesiology; Neal J. Cohen, professor of psychology; Andrew Webb, professor of electrical and computer engineering; and doctoral students Kirk I. Erickson, Paige Scalf, Gerry J. Jerome, David X. Marquez and Steriani Elavsky.