A simple blood test could potentially be used to detect signs of Alzheimer's disease before symptoms appear, researchers say.
Currently, biological tests to diagnose Alzheimer's use invasive and costly procedures including brain imaging and spinal punctures.
A team of researchers from the University of Newcastle in NSW believe they have developed a predictive blood test that is between 85 per cent and 90 per cent accurate.
The researchers analysed blood samples from 566 people, some with Alzheimer's disease, some with mild cognitive impairment and other with normal cognition, from a large international database.
Senior researcher Pablo Moscato said the aim was to develop a blood test that was cheap, reliable, non-invasive and could detect the disease early.
"The holy grail is to try and have a test that ... will not involve imaging, because when you see something with images it is perhaps too late," Prof Moscato said.
He said the test could be used to screen the wider population, or when people presented to medical appointments with mild cognitive impairment.
Prof Moscato said the test could be useful to determine whether such an impairment was likely to progress to Alzheimer's disease.
People with mild cognitive impairment did not necessarily develop Alzheimer's, Prof Moscato said. Some maintained that level of functioning or progressed to another form of dementia.
He said the test, which analyses proteins in the blood, increased in accuracy when used with a second test done one year later to examine the change in protein levels.
Prof Moscato said if biological markers for Alzheimer's were detected early it would allow people to make lifestyle changes, such as more exercise.
Alzheimer's Australia national research manager Dr Chris Hatherly said it could also help advance research on medical treatments to delay or reverse the disease.
"This is an important new development in the global effort to find simple, reliable and cost-effective measures to identify people with the earliest stages of dementia," Dr Hatherly said.
The research was published in the PLoS (Public Library of Science) ONE journal this week.