"While we already know that exercise is good for the heart and reduces the incidence of obesity, this study shows exercise can literally cause physical changes in the brain," explained Judy Cameron, Ph.D., a scientist in the divisions of Reproductive Sciences and Neuroscience at the OHSU Oregon National Primate Research Center. "Furthermore, we believe the study results show exercise causes a person to be more 'engaged' and provides another reason for Americans to make physical activity part of their daily regimen. This is especially true in the case of older Americans with whom decline in mental function over time is a common occurrence."
For this research project, scientists had to come up with a novel way to study exercise. They required conditions where extraneous environmental factors that could impact brain function were limited as much as possible. These factors include smoking, obesity and drinking, tendencies commonly found but difficult to regulate in human studies. To limit the effect of these factors on study results, researchers chose to conduct the research using nonhuman primates.
In all, 24 monkeys participated in the studies. The animals were separated into three groups: a "running" group, which exercised on treadmills for a set distance five days a week for 20 weeks. A second group did not exercise during this period, and a third group exercised for 20 weeks and then remained sedentary.
Following the exercise period, scientists then measured the volume of small blood vessels, called capillaries, in the motor cortex region of the brain in all three animal groups.
"What we found was a higher brain capillary volume in those monkeys who exercised than in those monkeys who did not. Specifically, changes were most noted in older animals that were 'less fit' at the start of the study," said Cameron. "The next step of this research is to determine whether other areas of the brain undergo physical changes. For instance, how are brain cells affected and does that impact cognitive performance?"
In the case of the mental performance study, scientists initially set out to determine if exercise impacted cognitive function or mood. For this study, scientists utilized several evaluation methods,including performance testing. One example is a test where a treat is placed under two toys. After a brief delay, the monkey was allowed to find the treat.
"Tests showed that animals in the exercise group were more aroused, alert and engaged than animals in the control group," said Cameron. However, it's important to note that both groups had essentially the same success rate. While more research needs to be done, this study did not demonstrate a relationship between exercise and increased cognitive function."
Another important finding occurred during a training exercise in which monkeys learned how to do the performance test. In this case, the exercise group animals learned how to do the test at a much faster rate.
In regard to both studies, scientists believe they have developed a very useful animal model for future studies on exercise and mental impacts.
Collaborators on the research included William T. Greenough, Ph.D., of the University of Illinois who directed the blood vessel studies; exercise physiologist Nancy I. Williams, Sc.D., of Pennsylvania State University; Henry Lange, Joan Bytheway and Kristin McCormick from the University of Pittsburgh; and visiting scientist Im Joo Rhyu of The Beckman Institute.
The ONPRC is a registered research institution, inspected regularly by the United States Department of Agriculture. It operates in compliance with the Animal Welfare Act and has an assurance of regulatory compliance on file with the National Institutes of Health. The ONPRC also participates in the voluntary accreditation program overseen by the Association for Assessment and Accreditation of Laboratory Animal Care International (AAALAC).