Regular exercise in old age could protect against brain shrinkage better than mental or social activities.
MRI scans of Scottish people aged 73 years old showed those who carried out more physical activity experienced less brain shrinkage than those who exercised minimally.
However, researchers found “no real brain-size benefit” from mentally challenging activities – such as reading a book or doing a crossword.
Brain shrinkage is linked to poor memory and thinking.
The study, published in Neurology, analysed the medical records of 638 people.
"Dementia is one of people's biggest fears in later life, but there are ways for people to help reduce their risk of developing the condition,” said a spokesperson from Alzheimer’s UK.
“Keeping your mind stimulated can be fun, but exercise has been proven to prevent cognitive decline in many studies. This research gives people further reason to get active and workout to ward off dementia.”