Alzheimer’s blood test revolution for over-50s

Condition could be detected 15 years before symptoms using much less invasive method

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 help tackle their symptoms more effectively.

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 50s, 60s and 70s 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 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.

The 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.

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 inserted into the lower back, between 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 a 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 the leading cause of death.

Several companies are working on tests for Alzheimer’s markers in the blood. 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 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 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, of the Alzheimer’s Society, called the study, published in JAMA Neurology, “a hugely welcome step in the right direction”.