How Alzheimer’s Research UK helped develop blood tests for Alzheimer’s

From funding one of the earliest studies into blood biomarkers to improving dementia diagnosis today, discover how decades of research are delivering earlier and more accurate ways of diagnosing dementia – moving us ever closer to a cure.

Sophie Evans’s dad Vincent died from mixed dementia in 2021. But the disease had already taken its toll on the family by the time he was diagnosed. “Our family couldn’t live a functional life because the long journey to a diagnosis and getting the support my dad needed was so difficult,” Sophie says. “If he’d had an earlier diagnosis, I’m certain things would have been easier for us all.”

To get an accurate diagnosis of Alzheimer’s disease, doctors need to confirm the presence of Alzheimer’s-specific proteins in the brain, by using PET scans or looking for faulty proteins in the spinal fluid. But PET scans are expensive and not widely available, and taking spinal fluid samples requires trained personnel and facilities that most memory clinics don’t have. As a result, fewer than 5% of people in the UK diagnosed with Alzheimer’s have received either of these tests.

“This means inevitably that some people are going to be misdiagnosed or not diagnosed at all” says Prof Jonathan Schott from University College London, Chief Medical Officer for Alzheimer’s Research UK. “It means people are not receiving the best possible diagnosis, which has implications for how they are treated and what counselling and support they get. It also means that they certainly would not be eligible for the next generation of therapies that are coming forward.”

But a simple blood test could change that. A blood test would be a cheap and accessible way to help someone identify whether their memory and thinking problems are caused by Alzheimer’s disease.

Blood tests for Alzheimer’s could become part of standard practice in the next few years. And this progress all started with a project funded by Alzheimer’s Research UK – that the person responsible almost didn’t pursue.

“It was a ridiculous idea”

To develop a blood test for Alzheimer’s, the first task is to find molecules that are measurably different in the blood of people with Alzheimer’s, compared to people without. This is known as a ‘biomarker’ – a sign that a future blood test will look for.

But it wasn’t a given that such a blood biomarker would exist. The movement of molecules into and out of the brain is tightly controlled by something called the blood-brain barrier. Would Alzheimer’s-related proteins ever make it out of the brain in large enough quantity to be detectable in a blood sample?

To find out, in 2000 Alzheimer’s Research UK invited proposals for a research grant to identify blood biomarkers. Prof Simon Lovestone, Distinguished Fellow at Johnson & Johnson Innovative Medicine, remembers it well – and originally refused to apply. “It was a ridiculous idea,” he recalls. “I said […] ‘you won’t ever find a blood-based biomarker, because why would you? The brain is separated from the rest of the body by the blood-brain barrier’.”

But after some persistent encouragement from his supervisor, Simon applied for the research grant, if only to prove his supervisor wrong. “To my surprise, I got the grant.”

Spot the differences

During the project, Simon’s team at King’s College London analysed blood samples donated by a group of 50 people with Alzheimer’s disease, as well as 50 people without.

In the end, they identified 15 proteins whose quantities changed in the blood in people with Alzheimer’s.

“I can’t tell you how much of a shock that was to me,” Simon says. “Everything I knew about how the brain worked, everything that I’d been taught, just went out of the window.”

The team’s findings, published in 2006, received huge interest from the scientific community. Research into blood biomarkers of Alzheimer’s exploded from then on.

And Simon believes our funding was critical. “I think it’s genuinely true to say that grant from Alzheimer’s Research UK opened the field to blood-based biomarkers. It showed that conceptually, they were possible.”

The hunt for a blood test

Simon’s team had proved it was possible to spot and measure differences in the blood of people with Alzheimer’s disease. The next step was to take this idea out of the lab and turn it into a blood test that can help diagnose people.

In time, this would be made possible by advances in protein detection technology, which can accurately measure tiny amounts of individual proteins in the blood. Prof Jonathan Schott from UCL says current machines are sensitive enough to detect “a grain of salt thrown into an Olympic-size swimming pool.”

In the last few years, one biomarker has emerged as a front-runner: phosphorylated tau 217, or p‑tau217 for short.

In May 2025, the US Food and Drug Administration (FDA) approved a blood test based on p‑tau217 to be used to aid diagnosis – the first Alzheimer’s blood test to be given this green light.

Bringing blood tests to everyone

Blood tests for biomarkers like p‑tau217 have shown great promise. Now we need to make them a standard part of the diagnosis of Alzheimer’s in the NHS. This is the goal of the Blood Biomarker Challenge.

Two trials, ADAPT and READ-OUT, have been funded through the Blood Biomarker Challenge, thanks to support from Alzheimer’s Research UK, Alzheimer’s Society, the National Institute for Health and Care Research, and Gates Ventures – including £5 million raised by players of the People’s Postcode Lottery.

In the READ-OUT trial, Dr Vanessa Raymont and her team will be evaluating multiple blood tests, for Alzheimer’s and other causes of dementia. “Both my parents lived with dementia so I know firsthand the devastation this disease causes, and how a timely and accurate diagnosis can benefit people and their families,” says Vanessa.

Prof Jonathan Schott and Dr Ashvini Keshavan are leading the ADAPT trial. Their team are investigating if using p‑tau217 blood test in memory clinics more accurately identifies people with Alzheimer’s disease – and crucially, whether that affects the care and the clinical trials they are eligible for.

The team will also assess the cost-effectiveness of the blood test, “which is vital if we want to provide the evidence required by the National Institute for Health and Care Excellence, [NICE] to make these blood tests available to everyone who will benefit,” Jonathan says.

He hopes the ADAPT and READ-OUT trials will lead to blood tests being used in memory clinics to help diagnosis Alzheimer’s within the next few years.

The promise of blood tests

Getting an accurate diagnosis is important for everyone coming to their doctor with concerns about memory and thinking. However, there are certain groups who are less likely to get an accurate diagnosis – including people from ethnic minorities, and those who live in poorer areas or far from specialist centres – and so who are particularly important to consider. Jonathan believes blood tests could help “democratise diagnosis” for everyone, no matter their background or where they live.

Blood tests are also helping drive clinical research forward. Clinical trials are already using blood tests to help select participants, which is lowering their cost and speeding up recruitment. Simon expects that, in the future, every drug a person receives will be based on a blood test. “You can trace that back to the Alzheimer’s Research UK investment,” he says.

The critical role of Alzheimer’s Research UK

Many people today still struggle to get a diagnosis – according to our research, one in five people wait over two years after seeing their GP for help. But with the help of blood tests for Alzheimer’s, that will change.

And 20 years on from his team’s groundbreaking study, Prof Simon Lovestone believes we wouldn’t be where we are today without our initial investment. “By having a smart idea, Alzheimer’s Research UK drove a research field”.

The development of blood tests is a vital part of the journey to a cure for dementia. With both effective diagnosis and new treatments on the horizon, Jonathan believes we’re reaching a tipping point when it comes to Alzheimer’s disease. “There is a real sense of excitement in the field – the sense that things are now all coalescing at the right time and we are on the cusp of making real progress.”

 

Prof Simon Lovestone B.M., Ph.D., MRCPsych., is Vice President, Distinguished Fellow Neuroscience, at Johnson & Johnson Innovative Medicine