A study review has confirmed the now widely accepted finding that exercise has a beneficial impact on mental health.
The new paper, to be presented to the American Psychological Association journal, finds that mental activity is sustained by exercise as individuals' age.
Reviewing studies in a range of research styles in order to make their examination as comprehensive as possible, the US researchers found that the evidence shows a significant relationship between physical activity and later cognitive function.
They concluded that exercise slows the effects of ageing and prolongs cognitive capacity well into older age, as well as decreasing the incidence of dementia.
"From this review we have found that physical and aerobic exercise training can lower the risk for developing some undesirable age-related changes in cognitive and brain functions and also help the brain maintain its plasticity – ability to cover one function if another starts failing later in life," said Dr Arthur Kramer, one of the study's authors.
He added that it is still not known how much exercise and of what sort has the most beneficial effect on the brain.
There are about 700,000 people with dementia in the UK, according to the Alzheimer's Society, only 18,500 of which are under the age of 65.