A team of researchers from four US universities have found that moderate physical exercise can help improve spatial memory in older adults.

Funded through the National Institute on Aging, the findings have been published in the 31 January edition of Proceedings of the National Academy of Sciences.

Scientists from the University of Pittsburgh; the University of Illinois; Rice University; and Ohio State University recruited 120 sedentary older adults without dementia for the study.

Particpants were placed in one of two groups - one following an exercise regime of walking for 40 minutes a day, three days a week, and the other limited to stretching and toning drills.

The results of the study found that the aerobic exercise group saw a greater volume increase in the parts of the brain that affect spatial memory.

Kirk Erickson, professor of psychology at the University of Pittsburgh, said: "We think of the atrophy of the hippocampus in later life as almost inevitable.

But we've shown that even moderate exercise for one year can increase the size of that structure. The brain at that stage remains modifiable."

Although the study did not consider memory loss in Alzheimer's or dementia sufferers, Dr Simon Ridley, head of research at the Alzheimer's Research Trust in the UK, welcomed the findings.

"Increasing evidence suggests regular exercise and a healthy diet may help reduce our risk of developing dementia as well as reaping numerous other benefits from living a healthy lifestyle," said Dr Ridley.