Physical exercise and keeping fit can protect against the onset of Alzheimer's disease, according to a study by the Centre for Human Psychopharmacology (CHP) at the Swinburne University of Technology in Australia.

The research by CHP shows that the rate of decline in certain aspects of memory may be explained by a combination of overall physical fitness and the stiffness of the central arteries.

The study, published in the Journal of Alzheimer's Disease, investigated the theory that fitness could be associated with better cognition through a healthier aorta.

A group of 201 adults (73 females and 29 males), aged between 60 and 90 years, living independently in aged care communities, were recruited for the study.

Their fitness was assessed with a six-minute walk test which involved participants walking back and forth between two markers placed 10 metres apart for six minutes.

Only participants who completed the full six minutes were included in the analysis, which assessed the stiffness of their arteries and cognitive performance.

The researchers found that – along with body mass index and gender – the combination of fitness and aortic stiffness explained a third of the variation in performance in working memory in older people.

Lead author Greg Kennedy says that from early adulthood, memory and other aspects of cognition slowly decline, with an increasing risk of developing into dementia in later life.

“Exactly why this occurs is unclear, but research indicates that exercise and physical fitness are protective,” Kennedy said.

“A healthier, more elastic aorta is also theorised to protect cognitive function, by reducing the negative effects of excessive blood pressure on the brain.

“People generally are less fit and have stiffer arteries as they age, which seems to explain the difference in memory ability that is usually attributed to ‘getting older’.

“Unfortunately, there is currently no effective pharmacological intervention that has proven effective in the long term in reducing this decline or staving off dementia.

“The results of this study indicate that remaining as physically fit as possible, and monitoring central arterial health, may well be an important, cost-effective way to maintain our memory and other brain functions in older age.”