Regular exercise may protect against the “normal” memory decline of aging. I’m reluctant to think of any memory loss as normal. But by age 65, more than half of adults say they are concerned about memory problems.

Research from the University of Pittsburgh, however, is encouraging. It suggests that we can fight back against memory loss.

In the study, older adults were divided into two groups. One group walked briskly for 40 minutes per day, three times a week. The other group performed stretching exercises for the same amount of time.

One year later, people in both groups were more physically fit than they were when the study began. The walkers, however, improved significantly more than the stretchers. All the participants did better on memory tests. But yet again, the walking group did even better than the stretching group.

Moreover, test scores correlated closely to brain scans taken at the start of the study and one year later.

A structure in the brain, the hippocampus, helps process memories. It shrinks 1-2% for every year we age. The stretching group saw a 1.4% decline. That fits with the average expectation.

The hippocampus of walkers actually got 2% bigger on average. Memory test scores tended to correlate with hippocampus size.

Exercise probably does not prevent major neurological disorders that contribute to memory loss, such as Alzheimer’s disease and most other forms of dementia.

But otherwise, this study is good news. It provides evidence that a shrinking hippocampus — and memory loss — may not be inevitable.

Your doctor likely already recommends moderate exercise. And this is one more reason to do it. And the work is manageable: three sessions per week of moderately vigorous aerobic activity.

It may motivate you to know that exercise doesn’t just help your muscle strength. It also boosts your brain power.