Care for the elderly could be slashed if older people took a little more exercise, according to a new study.

Work done in the filed was presented to a conference in Amsterdam, where scientists showed that active older people could ward off Alzheimer's disease.

Those exercising at least twice a week as they get older, as well as following a balanced diet, were said to halve their risk of the disease.

Neurologist Miia Kivipelto told Reuters that an active mental and physical lifestyle offered a viable "preventive" measure.

"It's never too early to start to prevent Alzheimer's disease," she explained.

Alzheimer's affects about 12 million people worldwide.