Scientists in Australia and Japan have developed a blood test they say may help detect Alzheimer's up to 20 years before symptoms arrive.
The test accurately detects the level of amyloid in the brain. It's thought the buildup of this sticky substance contributes to Alzheimer's disease.
According to the researchers this plaque can be present two decades before symptoms of the disease begin, meaning the test could become an early way of diagnosing the disease.
The test was developed by a group of scientists including researchers from the Florey Institute for Neuroscience in Melbourne.
"We have developed a super sensitive blood test that predicts who is going to develop the disease many years in advance," says Professor Colin Masters, researcher at Florey Institute.
The test can identify beta amyloid, a sticky substance which is part of a larger protein in the blood.
This plaque accumulates microscopically in the brain, causing nerve damage.
"That is the principle cause of Alzheimer's disease," says Professor Masters.
According to the team at the Florey its presence in a blood test allows Alzheimer's to be detected up to 20 years before the first symptoms show.
Doctors currently use brain scans to detect the presence of beta amyloid. The Florey institute found the blood test to be 90 per cent accurate compared with the scans.
The blood test is cheaper and less invasive than the brain scans or the lumber punctures currently used.
The test is not something people could get in their local clinic, it requires laboratory analysis, but biostatistician Dr. James Doecke from CSIRO (Commonwealth Scientific and Industrial Research Organization) says it's highly significant in the field. "We're at least ten percent better in accuracy than what we have been ever," he says.
Whether people will want an early diagnosis, before any treatment is available remains to be seen, but researchers here say it could be used to accurately screen people suitable for clinical trials.
A growing body of research is aimed at slowing down the development of symptoms. "So we can sort of push back the onset of symptoms maybe five years," Doecke says. "That will be fantastic."
Alzheimer's Research UK describes the study as robust, but it says it is "a useful step in validating its potential as a diagnostic tool."
But it cautions: "Given the risk of false positives or negatives from tests like this, further work with more people will need to build on this study to understand how well this approach could predict those who will go on to develop symptoms of Alzheimer's in the future."
Wayne Griffin discovered he had Alzheimer's disease when his memory and motor skills started failing him.
Researchers hope eventually they will be able to produce a diagnostic test which allow them to test drugs on patients before this happens.