Exercise: Working Out the Memory as Well as the Muscles

March 25, 2007

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By ERIC NAGOURNEY

Exercise, researchers have found over the years, appears to help

people fight the natural memory loss that comes with aging.

Now a new study suggests a possible explanation for why this is so.

The report, which appears online in The Proceedings of the National

Academy of Sciences, says working out may stimulate the growth of

neurons in a part of the brain associated with memory loss.

The researchers, led by Dr. A. Small, an associate professor

of neurology at the Columbia University Medical Center, looked at

changes in the brains of volunteers who worked out on exercise

equipment.

The researchers were trying to confirm the findings of earlier

research they did involving mice. When the mice exercised, blood

flow increased to a part of the brain called the hippocampus, and

more specifically to the dentate gyrate. In post-mortems, the

researchers found evidence of neuron growth in the dentate gyrate.

The research could not be replicated in people for reasons

practical — who would volunteer? — and ethical, to say nothing of

legal.

But using 11 volunteers, an M.R.I. machine and equipment like

treadmills, the researchers were able to see whether blood flow

increased to the same part of the brain in humans as it had in mice.

It did, suggesting that working out may help produce neurons in a

part of the hippocampus that loses them disproportionately as people

age.

The researchers also found that as the volunteers went through a

three-month exercise period, their scores on memory tests went up.

" Our study does suggest that it's probably aerobic exercise that's

inducing this effect, " Dr. Small said.

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