Losing your memory is a problem you may not be worried about now, but it is something many people fear as they get older. And if you've had experience of a family member or friend suffering from dementia or Alzheimer's disease, you'll know only too well why it's important to take whatever steps you can to avoid it.
Walking, say the researchers, may help stop your brain shrinking when you get older - and that may protect against age-related mental decline. But you need a good walk every day, since tests showed covering a distance of between six and nine miles a week had the best results.
The experts, whose study appears in the journal Neurology, observed almost 300 older people and recorded how far they walked every week. After subjecting them to brain scans, the researchers found the volunteers who walked at least six to nine miles a week had more grey matter in their brains than the others.
Then, after following the volunteers for 13 years, the experts gave them tests to find out if they were suffering from mental decline. They discovered the volunteers who walked the most were 50% less likely to have developed memory problems than those who walked the least.
So how much walking do you do in an average week? Has this study persuaded you that you should do more?