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The Alzheimer’s disease test measures for high levels of the amyloid beta protein in the blood. Photo: Shutterstock

Alzheimer’s: 30-year wait is over for early-warning blood test that’s highly accurate

The test detects the build-up of the amyloid-beta protein that’s linked to the disease. It can appear decades before dementia symptoms become apparent

Lydia Hales

Scientists have developed a new blood test that can predict if a person is at risk of developing Alzheimer’s disease. The test, which has a 90 per cent accuracy rate, identifies people who have high levels of a protein in their brain that is associated with the disease.

The test could be used for frontline screening, to help speed up the selection of participants for clinical and prevention trials in two to three years, says Professor Katsuhiko Yanagisawa, director general of the Research Institute at the National Centre for Geriatrics and Gerontology in Japan, and lead author of the study published in the journal Nature today.

Alzheimer’s disease is the most common form of dementia, for which there is no preventive drugs or cure. Photo: Alamy

The test measures a specific sign, or biomarker, in blood plasma which can indicate abnormal levels of amyloid-beta in the brain. It can appear decades before dementia symptoms become apparent. Amyloid-beta is a small protein fragment that clumps together in the brain to form plaque, and has long been linked to Alzheimer’s. The disease is the most common form of dementia, for which there is no preventive drugs or cure.

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Nobel laureate Dr Koichi Tanaka is also part of the team, and developed the initial technique involved in the test.

While highly sensitive, the test is cheaper and less invasive than the current options of a PET scan or painful lumbar puncture which involves drawing cerebrospinal fluid from the spinal canal with a needle.

A graphic of the current options available for determining if the person has a high level of the protein, compared to the new blood test method.

“The number one use would be for screening participants to come into clinical trials, particularly in the preclinical phases. That is when people are cognitively normal, before the onset of any cognitive impairment, or even in the presence of mild cognitive impairment,” says Professor Colin Masters of the Florey Institute in Australia.

We can finally say that we have a high-performing blood test
Professor Colin Masters

“The test itself has accuracy of 90 per cent at predicting people who are at risk of developing Alzheimer’s because they have of a build-up of this protein in the brain. This blood test will help determine whether this person is on an Alzheimer disease pathway, or, if they have some other cause for their cognitive impairment.”

The technique was tested in Japan on two independent groups (samples from 121 Japanese and 252 Australians) which included individuals with no cognitive impairment, those with mild cognitive impairment, and those with Alzheimer’s.

Professor Colin Masters of the Florey Institute in Australia.

The team has been working on a blood test for several decades. It still needs to be scaled up before it can be more widely used.

“This is a 30-year odyssey, and it’s only with these results coming out in Nature that we can finally say that we have a high-performing blood test,” says Masters.

“The test could also potentially be used for [wider] population screenings; it may be useful in distinguishing different types of dementia once the dementia is fully expressed, or it may have prognostic implications, which means that the test may contain information about how fast this person is going to deteriorate.

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“Finally, we could use the test in monitoring the efficacy of any intervention, particularly in those interventions that are directed at clearing this abnormal protein from the brain.”

He added that only in the next phase will they know whether the test will be useful for all these conditions.

The team is currently looking for healthy volunteers to participate in a trial. For more information visit Early Trial.