Neural aging walks tall: aerobic activity fuels elderly brains, minds.

Seniors interested in pumping up their brains and maintaining an attentive edge might consider taking this inexpensive prescription: Go for a walk every 2 or 3 days. Don't sweat it, but make an effort. Limit each walk to between 10 and 45 minutes.

That's the conclusion, at any rate, of two new studies that demonstrate for the first time in people that physical fitness, whether achieved on one's own or through a brief aerobic-training course, induces brain changes associated with improved performance on an attention-taxing task.

"Even moderate cardiovascular activity of the sort that is within reach of most healthy older adults results in improved neural functioning and may help to extend or enhance independent living" says neuroscientist Arthur F. Kramer of the University of Illinois at Urbana-Champaign. Kramer directed the new studies with his colleague Stanley J. Colcombe.

Prior research showed that mice score higher on tests of learning, memory, and attention after regularly exercising on a running wheel for several weeks. In the animals, this training boosts the brain's blood supply, increases connections between neurons, and promotes the development of new brain cells.

Moderate exercise works similarly in people, Kramer and Colcombe's team reports in an upcoming Proceedings of the National Academy of Sciences.

The scientists first assessed physical fitness in 41 older adults, ages 58 to 77, after each walked 1 mile. Participants then performed an attention task in which they viewed arrays of five left-or-right-pointing arrows and used computer keys to indicate whether the central arrow pointed left or right.

During testing, a functional magnetic resonance imaging (fMRI) scanner measured the rate of blood flow in specific regions of each volunteer's brain.

Adults identified as particularly fit made judgments about the arrows faster and with equal accuracy compared with their less fit peers. Moreover, the fMRI data show that highly fit seniors exhibited intense blood flow in frontal-brain areas implicated in allocating attention and minimal neural activity in a frontal region that usually perks up in situations of indecision.

In a second study, 15 elderly volunteers accomplished attention tasks markedly faster after completing a 6-month aerobic-training course than they had before the course started. Participants gradually built up to walking for 45 minutes at a moderate pace three rimes each week. By the end of the study, these volunteers' brain activity resembled that of highly fit seniors in the first study.

In contrast, 14 seniors who completed a 6-month course of stretching and toning exercises, but not aerobic exercise, showed little improvement on the attention task. Their brain activity was similar to that of less-fit seniors in the first study.

Colcombe and Kramer's studies are "an impressive achievement," remarks psychologist Timothy Salthouse of the University of Virginia in Charlottesville. Further research should examine whether aerobic training enhances seniors' performance on other psychological tasks and whether such improvements confer any advantages in daily life, Salthouse says.

Kramer and his colleagues are now testing whether aerobic training might improve seniors' driving skills.