Exercise 'cuts Alzheimer's risk'

Regular exercise reduces the risk of dementia and Alzheimer's disease by up to 40%, US research suggests.

The University of Washington study claims to be the most definitive investigation into the effect of exercise on dementia.

The Annals of Internal Medicine study found the more frail a person was, the more exercise was likely to help them.

A regular gentle work-out was enough to produce a positive effect - even for people aged over 65.