A new study provides yet more evidence that exercise can help prevent mental decline.
U.S. neurologists report that regular walking may protect the brain against shrinking and preserve memory in the elderly.
The study, which appears in the journal Neurology, looked at 299 dementia-free people and 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 sizes. After four more years, the seniors were tested to see whether they had developed dementia or a milder condition called cognitive impairment.
The study found that people who walked at least 72 blocks, or roughly nine to 14 kilometres, per week had greater "gray matter" volume -- the material that makes up the majority of the brain -- than people who didn't walk as much.
They found that walking more than 72 blocks a week did not appear to increase gray matter volume any further.
Tests were then administered to determine who had developed dementia. They found 40 per cent of the seniors had developed cognitive impairment or dementia 13 years after the study began. But those who walked the most cut their risk of developing memory problems in half.
Study author Kirk I. Erickson, with the University of Pittsburgh in Pittsburgh, notes that brain size shrinks in late adulthood, which can cause memory problems.
"Our results should encourage well-designed trials of physical exercise in older adults as a promising approach for preventing dementia and Alzheimer's disease," he said in a news release.
"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.
The study, supported by the U.S. National Institute on Ageing, is just the latest medical study to show how exercise can stave off dementia. Earlier this year, a study presented at an American Association of Neurology conference found that being physically active throughout life appears to lower the risk of dementia in old age, and that the earlier in life that exercise happens, the better.
Other research has shown that resistance training can slow cognitive decline in seniors while also improving strength and mobility.
