Physical exercise such as walking, gardening and dancing could help to reduce the risk of developing dementia, according to a new medical study.

Research found such activities can increase brain volume and help stave off the neurodegenerative disease.

Participants were asked about their physical habits and had MRI scans of their brains, which were analysed to measure the structures associated with memory.

Dr Doug Brown, director of research and development at Alzheimer's Society, said: "Keeping physically active is one of the best ways you can reduce your risk of dementia.

"People who find the idea of running or cycling a long way daunting will be pleased to see that other forms of activity such as dancing, gardening and hiking also appear to have benefits.

"Other ways you can reduce your risk include avoiding smoking and eating a healthy, balanced diet."

He added: "This paper adds to this body of evidence by suggesting that different kinds of exercise can have a positive effect on the brain.

"However, we need to dig deeper to understand how this effect on the brain influences dementia risk."

The investigation, carried out by UCLA Medical Centre in California and the University of Pittsburgh, studied 876 patients aged on average 78.