Bradley Hatfield, professor in the University of Maryland, College Park, School of Public Health, uses high tech brain imaging to study the benefits of exercise on the aging brain.
In this Q&A, Hatfield describes his early results, which show that moderate physical activity may help maintain memory function longer, maybe even for years, in people with genetic predisposition to Alzheimer's Disease. More good news for boomers – even for people who haven't been exercising, it might not be too late. Media may use all or parts of this interview, with attribution to Professor Hatfield.
What are you trying to learn with your research on exercise and the aging brain?
HATFIELD: We are trying to determine if physical activity slows or delays age-related change in the brain, particularly in those who are genetically susceptible to Alzheimer's Disease. Memory-related structures are among the brain regions that are affected in the earliest stages of Alzheimer's Disease and, importantly, physical activity results in the release of neurotrophins (factors that promote growth and repair of neural tissue), particularly in these regions. This has been clearly shown in animal studies. These neurotrophins would counteract the ravages of the disease. Therefore, we are using neuroimaging to determine if these brain regions are positively affected by exercise in human subjects. Support for this prediction would imply that physical activity would be of great importance to maintain memory and cognitive function in men and women who are at genetic risk for Alzheimer's Disease. That is, it could prevent appearance of symptoms for some time - perhaps even years.
What are your methods?
HATFIELD: We use neuroimaging tools such as EEG (electroencephalography), MEG (magnetoencephalography) and magnetic resonance imaging (MRI) to take pictures of the brain both at rest and at work. We're also doing cognitive testing. We then compare the "pictures" from different groups to determine differences as related to physical activity levels and genetic factors.
How is your research different from other studies?
HATFIELD: I think the main difference is that we are using neuroimaging to assess brain activity in middle-aged men and women who are cognitively intact but differ in their genetic risk for Alzheimer's Disease. That is, we can detect differences in brain processes as related to a sedentary lifestyle even though the cognitive performance appears normal. This is because the brain can compensate for decline, and it appears to function the same as in those who are physically active, but neuroimaging can reveal if it is working harder to overcome any deficits. This kind of inefficiency would not be discernible through cognitive or behavioral testing.
What have you found?
HATFIELD: We have found that physically active individuals, who carry the gene that makes them more susceptible to Alzheimer's (APOE e4), show brain activation profiles during memory challenge that are similar to non-carriers who are at lower genetic risk of Alzheimer's. In essence, this implies a protective effect of exercise on the brain. On the other hand, carriers of the gene who are sedentary show reduced brain activation that implies some degree of neurodegeneration in the memory-related regions of the brain.
What level of exercise seems to make the difference?
HATFIELD: It's not well established at this time, but it seems that a moderate degree of physical activity, such as brisk walking three or more times per week, for 20 minutes or more per session, is sufficient from what we know generally about physical activity and health. Much more work remains to be done.