Preliminary medical testing results have shown that aspirin may prevent dementia and intestinal cancers.

The study of 15,000 healthy Australians aged over 70 was the largest ever clinical trial on the use of aspirin to prevent disease in the elderly.

Professor Mark Nelson from Hobart's Menzies Research Institute says the clinical trials could lead to cheap and simple treatment procedures.

"Remember aspirin is an over-the-counter medication; you don't need a doctor to prescribe it, you don't need a doctor to tell you you've turned 70," he said.

"So this is something that can be done very simply, very cheaply if we find that it's an effective strategy."

Aspirin is already used to treat patients who have suffered heart attacks or strokes because it reduces the risk of further heart attacks or strokes by 23 per cent.

Professor Nelson says the clinical trials suggest aspirin may be effective in delaying the onset of dementia.

"There's a number of reasons why it might. I mean the number one reason would be related to strokes. If you have a stroke you knock out a large area of your brain and therefore your ability to think is affected," he said.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Listen Duration: 3 minutes 24 seconds 3 m 24 s Asprin may prevent certain cancers, mental decline ( Felicity Ogilvie ) Download 1.6 MB

"There are also the possibility of lots of what are called microinfarcts, which means small areas of brain getting knocked off very slowly."

Health benefits could be good for economy, professor says

He says the public health benefits of aspirin could also have positive side effects for the economy.

"Cognition or cognitive decline is a very important public health issue and if we could delay people's onset of dementia, for example, by two years we would save the public funds billions of dollars a year because they wouldn't need to go into facilities," Professor Nelson said.

However, Professor Nelson has also acknowledged the 'catch-22' of aspirin, which can also lead some people to have a major stroke because of increased blood flow.

"Aspirin actually can cause an increase in your risk of hemorrhagic stroke, bleeding type strokes and it can also cause bleeding into the stomach," he warned.

"In actual fact, the bleeding type stroke for a patients is a more catastrophic event. It's more likely to leave you disabled or to kill you.

"That's why you do clinical trials. It means when us doctors really don't know if you use it as a strategy, does it do overall good or does is it do overall harm."

The study also found that aspirin may be able to prevent some cancers, particularly gastro-intestinal cancers.

"There's some very good evidence around to suggest that aspirin may prevent cancers especially cancers of the gastro-intestinal tract," Professor Nelson said.

"Now that makes sense because you take it orally so in aspirin you've got that natural component."