Alzheimer’s blood test could pave way for routine screening on NHS within years

A blood test identifying people at high risk of Alzheimer’s Disease with 94 per cent accuracy could pave the way for routine screening on the NHS within years, scientists have said.

The test can pinpoint people with high levels of amyloid and tau proteins, which build up in the brain to cause Alzheimer’s.

A study of 786 people found the blood tests to be extremely accurate at determining who was at high, intermediate and low risk of having or developing the disease, so that they can be given more extensive tests to get a final diagnosis.

There are currently no Alzheimer’s blood tests approved for use in the UK.

At the moment, the only way to prove that someone has a build-up of these proteins in the brain is to have a lumbar puncture, which is costly and invasive, or an amyloid PET scan, which is only available in about 1 in 20 NHS memory clinics.

But significant advances in recent years mean that blood tests showing those at high risk are expected to become available on the NHS within five years.

The trial of this new blood test confirms their potential and suggests they could become common even sooner than that, researchers said.

This blood test, developed by scientists at Gothenburg University in Sweden, confirms that the tau 217 protein is the best ‘marker’ for Alzheimer’s to look for in a blood test.

And, as the first in a number of tau 217 blood tests being developed to publish trial results, the high accuracy provides good evidence that blood tests are a viable option for screening in the coming years – as long as further trials back up these findings, scientists say.

“The blood test gives all patients access to a biological test to help a doctor give a more informed decision. This was simply not possible before. The blood test can be done regularly so person can be monitored on annual or bi-annual basis,” Nicholas Ashton, of Gothenburg University, told i.

He says the blood test could be available in UK specialist clinics within a year – with ALZpath, the US Alzheimer’s diagnostics company commercialising the test, in talks with various UK labs about using them later in 2024.

And within five years Alzheimer’s Society and Alzheimer’s Research UK are confident that blood tests could be rolled out across the NHS – although further trials and regulatory approval would be needed before this, or any other blood test, was used.

Dr Ashton is now conducting larger tests in more than 20,000 people in Scandanavia to confirm the results.

Scientists not involved in the research hailed the blood test as a key development in the race to develop a game-changing diagnostic tool.

“If these findings are replicated in real-world clinical settings, the p-tau 271 [blood test] has the potential to revolutionise the diagnosis of Alzheimer’s Disease,” said Professor Jonathan Schott, of UCL Queen Square Institute of Neurology.

Professor Charles Marshall, of Queen Mary University of London, said: “These findings show that a blood test can accurately detect the presence of the proteins that build up in the brain to cause Alzheimer’s disease.

“The hope is that blood tests like this will improve access to a diagnosis in those seeking help for memory problems, and ultimately ensure that people can benefit from emerging treatments that can slow the progression of Alzheimer’s disease.”

Professor David Curtis, of UCL Genetics Institute, added: “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.”

Dr Sheona Scales, Director of Research at Alzheimer’s Research UK, said: “People with dementia frequently face unacceptably long delays getting a diagnosis, and with new treatments finally on the horizon, it’s never been more important to transform the way people with potential symptoms of Alzheimer’s are diagnosed.”

Dr Richard Oakley, Associate Director of Research and Innovation at Alzheimer’s Society, said: “This study is a hugely welcome step in the right direction as 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.

“However, we still need to see more research across different communities to understand how effective these blood tests are across everyone who lives with Alzheimer’s disease”.

“Coming down the line are potentially ground-breaking new drugs which can slow the progression of early-stage Alzheimer’s disease, but for people to be eligible for them if they’re approved in the UK, they will need an early, accurate diagnosis” Dr Oakley added.

After 20 years with no new Alzheimer’s drugs new treatments such as donanemab and lecanemab, which clear amyloid plaques, are expected to be approved by UK regulator with as little as a year.

The trial results are published in the journal JAMA Neurology.