IN BRIEF
- The so-called p-tau217 test had previously been used only on those with symptoms.
- Some experts are already calling it a "game changer".
What if a simple test could reveal your risk of Alzheimer's years before memory problems start?
A new study on a specific blood test shows this might be possible.
The test looks for what doctors call 'p-tau217' and can alert them to the disease five to 10 years before a healthy person develops symptoms.
That information could be reassuring or terrifying, but for now, it's a potential tool to speed drug development by helping to identify and enrol high-risk people into studies of possible Alzheimer's treatments or preventive strategies.
The scientists behind the study, Reisa Sperling from the Mass General Brigham Neuroscience Institute in the US, said the so-called p-tau217 test had previously been used only on those with symptoms.
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"Right now it's really being utilised in people who already have symptoms of Alzheimer's disease and are thought to have cognitive impairment due to Alzheimer's disease," she said.
"In this study, we are looking at people who do not yet have symptoms of Alzheimer's disease."
How does the Alzheimer's test work?
The results, presented at the Alzheimer's Association International Conference in London, showed similar patterns in those at risk of developing Alzheimer’s.
It found that symptom-free older adults who harboured very high levels of p-tau217 in the blood test had a 38 per cent risk of developing cognitive impairment over five years. That risk grew to 78 per cent by 10 years.
"We also found that people who have a very low level of this blood test, p-tau217, were very unlikely to progress over time and were about the same level as people in general as they age over a 10-year period might be at risk for developing impairment," Sperling said
She said the blood test data offers some new clues. While different intermediate levels of p-tau217 signalled progressive risk, only the very highest level seemed to correlate with other evidence about that tipping point.
Researchers analysed data from 2,684 healthy older adults enrolled in long-running Alzheimer's studies since 2004, all of whom took the test when they joined. By last year, 478 of them had developed cognitive impairment.
A 'game changer'
The test can reveal a person's risk years in advance, information that may be reassuring for some and distressing for others, but it does not offer a cure.
"At this point, it wouldn't change what I would tell someone to do. I'd still tell them to eat well, sleep well, exercise a lot and stay engaged. But that's going to change dramatically if the current prevention trials show clinical benefit," Sperling said.
Already, large clinical trials are testing whether certain drugs could prevent or at least delay the disease.
If any of those works, doctors should have an easy way to tell who should try them — and the blood test can be exactly what they need.
That is why Jessica Langbaum from the Banner Alzheimer’s Institute based in the US, explained the development as a "game changer" for neary 10 people who are diagnosed with Alzheimer's every year.
"This is really important for people, particularly if we get to a time when there's one of the treatments that are being tested for Alzheimer's prevention therapies," she said.
"If one of those treatments read out having a blood test that can accurately determine who to test and say, yes, this person might be eligible for treatment, I think that's a real game changer."
— With additional reporting by the Associated Press
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