Moderate exercise had an effect
Exercise may help improve mental performance in adults with mild memory problems, research suggests.
A University of Melbourne team tested the impact of a home-based physical activity programme on 138 volunteers aged 50 and over with memory problems.
Those who took part showed a modest improvement in cognitive function compared to those who did not.
The Journal of the American Medical Association study suggests exercise may help ward off severe mental decline.
Dementia is already a serious problem, and the number of people with Alzheimer's disease, the most common form of the condition, is predicted to quadruple worldwide over the next half century.
The latest study focused on people with mild cognitive impairment, a term used to describe memory problems that are not serious enough to interfere with everyday life.
It does not necessarily lead to dementia, but does increase risk of developing the condition.
Some volunteers were asked to complete three 50-minute sessions a week of moderate physical activity, such as walking, for 24 weeks. Others were not asked to increase their exercise levels.
At the end of the study, the people in the exercise group achieved better scores in tests of their cognitive function, and lower scores in tests to determine signs of dementia.
Follow-up showed that the benefits persisted for at least another 12 months after the exercise programme was stopped.
Exercise is known to help keep the cardiovascular system healthy, and may help boost cognitive function by boosting blood supply to the brain.
Writing in the journal, the researchers said: "Unlike medication, which was found to have no significant effect on mild cognitive impairment at 36 months, physical activity has the advantage of health benefits that are not confined to cognitive function alone, as suggested by findings on depression, quality of life, falls, cardiovascular function, and disability."
Dr Susanne Sorensen, head of research at the Alzheimer's Society, said: "Regular exercise is one of the best ways to reduce your risk of dementia and can help slow progression of the condition.
"This study demonstrates that exercise improves cognition in people with mild cognitive impairment, and that there is a lasting effect even after the exercise intervention stops.
"We need more research to investigate whether exercise not only improves cognition, but also stops people with mild cognitive impairment developing dementia."