Walking may slow down decline of brain in old age

Researchers at the University of Pittsburgh in the US studied 299 healthy older people who recorded the distances they walked in a week.

Nine years later, the volunteers were given scans to measure their brain size. Then after another four years they were tested to see if they were suffering from mental decline or dementia.

The first test showed that people who walked at least six to nine miles per week had more "grey matter" in their brains than those who did not.

Grey matter consists of the cell bodies of neurons, rather than the fibres that transmit signals. Walking greater distances did not appear to preserve grey matter any further.

The findings are reported in the journal Neurology.