Walking at least 10 km per week may protect your brain size and preserve memory in old age, suggests a new study.
"Brain size shrinks in late adulthood, which can cause memory problems," said study author Kirk I Erickson from the University of Pittsburgh in the US.
"Our results should encourage well-designed trials of physical exercise in older adults as a promising approach for preventing dementia and Alzheimer's disease," Neurology journal quoted him as saying.
For the study, 299 dementia-free people recorded the number of blocks they walked in one week. Then nine years later, scientists took brain scans of the participants to measure their brain size, says a Pittsburgh release.
After four more years, the participants were tested to see if they had developed cognitive impairment or dementia.
The study found that people who walked six to nine miles had greater gray matter (associated with intelligence) volume than people who didn't walk as much.
Researchers found that those who walked the most cut their risk of developing memory problems in half.
"If regular exercise in midlife could improve brain health and improve thinking and memory in later life, it would be one more reason to make regular exercise in people of all ages a public health imperative," said Erickson.