LONDON - A blood test that detects Alzheimer’s 10 to 15 years before a patient shows symptoms could be used to screen all over-50s.
Measuring levels of a protein in the blood called p-tau217 has been shown to be cheaper, easier and at least as accurate as the current diagnosis options, a study has found.
The protein is a sign of disease in the brain caused when tau starts to attack neurons. This can occur up to 15 years before symptoms such as forgetfulness and cognitive decline start.
More than one million people are expected to be living with Alzheimer’s or dementia in Britain by 2030 and it is hoped that beginning early treatment could make it easier to tackle their symptoms.
Experts believe the blood test could become as routine as monitoring cholesterol to help prevent heart disease.
Researchers from the University of Gothenburg looked at data on almost 800 people in their fifties, sixties and seventies from three different trials that used a combination of data from the makers of the blood test Quanterix and lab tests. They compared the blood test with current methods, such as a lumbar puncture to screen spinal fluid, or a PET scan.
The test was able to categorise people into likely, intermediate, or unlikely to develop Alzheimer’s and data showed measuring p-tau217 in the blood could be just as good as the existing tests with an accuracy of more than 95 per cent.
Improved screening
The new findings have the potential to “revolutionise” diagnosis for people with suspected Alzheimer’s, experts say, and could pave the way for a screening process for all people over a certain age.
Currently, only two per cent of eligible patients in the UK get a PET scan or lumbar puncture, also known as a spinal tap, with thousands unable to access the diagnostic tools.
A lumbar puncture involves a needle being inserted into the lower back, between the bones in the spine.
“When effective treatments to prevent the progression of Alzheimer’s disease become available it will be essential to be able to identify people who are at high risk before they begin to deteriorate,” said David Curtis, honorary professor at UCL Genetics Institute.
“This study shows that a simple blood test might be able to do this by measuring levels of tau protein in the blood which has been phosphorylated in a specific way.
“This could potentially have huge implications. Everybody over 50 could be routinely screened every few years, in much the same way as they are now screened for high cholesterol.
“It is possible that currently available treatments for Alzheimer’s disease would work better in those diagnosed early in this way.”
There are estimated to be 944,000 people living with dementia in Britain, with the majority suffering from Alzheimer’s. One in three people born in the UK this year is expected to develop dementia in their lifetime.
The condition costs the country £34.7 billion annually and is now the leading cause of death.
New tests on way
Several companies are working on making tests for Alzheimer’s markers in the blood and last year Alzheimer’s Research UK and the Alzheimer’s Society launched a £5 million project in an attempt to make them available on the NHS.
The latest study is being celebrated because of its high level of accuracy and the fact that it shows for the first time that a blood test can be as accurate as a lumbar puncture at detecting p-tau217.
The new test has been used by scientists but has not yet been made available to the public and has not been approved or submitted to medical regulators, such as the FDA or MHRA.
The hope is that people could get a quick blood test and be told if they are “likely”, “unlikely”, or of “intermediate risk” for Alzheimer’s and further tests or treatment could then be prescribed.
Dr Richard Oakley, associate director of research and innovation at the Alzheimer’s Society, called the study, published in JAMA Neurology, “a hugely welcome step in the right direction”.
“It shows that blood tests can be just as accurate as more invasive and expensive tests at predicting if someone has features of Alzheimer’s disease in their brain,” he said.
“Furthermore, it suggests results from these tests could be clear enough to not require further follow-up investigations for some people living with Alzheimer’s disease, which could speed up the diagnosis pathway significantly in future.”
Experts now want to see larger, more diverse trials to see how accurate and robust the test is and how easy it would be to implement in the real world.
