Blood Biomarker Challenge to 'revolutionise' dementia diagnosis

Blood-based biomarkers could be the cost-effective, accurate and non-invasive diagnostic tool that is needed to revolutionise diagnosis.

With an estimated third of people living with dementia currently undiagnosed, there is a clear need to improve the speed and accuracy of dementia diagnosis. Alzheimer's Society is hoping to achieve this through the Blood Biomarker Challenge.

What is the Blood Biomarker Challenge? 

This collaborative project with Alzheimer's Research UK and the National Institute for Health and Care Research (NIHR) will pilot the use of dementia blood tests in the NHS. The Blood Biomarker Challenge is a £5million award that hopes to revolutionise dementia diagnosis in the UK. 

A blood-based biomarker is an indicator about a person’s health that can be measured by testing their blood. These biomarkers are poised to be a critical tool for dementia diagnosis in the future, by helping speed up the diagnosis process.

It's hoped the tests will be able to diagnose different forms of dementia, such as Alzheimer’s disease, earlier and more accurately than current methods.

Blood tests for Alzheimer’s disease exist and have been extensively tested in research studies to show that they are accurate in diagnosing Alzheimer’s disease. They are also used in distinguishing it from other diseases that cause dementia.  

However, we are lacking the evidence to implement these blood tests into the NHS as they have not been tested in diverse patient groups in the UK. This evidence is crucial to their roll out and so more research is needed before they are ready to be used in a clinical setting in the UK.

How can Alzheimer’s disease be diagnosed using blood testing? 

Researchers are now developing biomarker tests that can detect two proteins called amyloid or tau proteins in the blood. These proteins both build up in the brain in Alzheimer’s disease, and when detected in blood could be used to indicate that they are also present in the brain.  

As amyloid and tau protein build up in the brain, our body tries to clear away these proteins. As a result, they can end up in spinal fluid, the special liquid which surrounds the brain and spinal cord and protects them.

• Spinal fluid is connected to our blood stream by the brain-blood barrier. While researchers do not fully understand how these proteins reach the blood, theories include:
• The brain-blood barrier becomes leaky in Alzheimer’s disease and allows amyloid/tau to escape into the blood. 
  Amyloid/tau protein can be produced in other parts of the body and naturally finds its way into the blood. 

Who will carry out the research? 

The READ-OUT (REAl world Dementia OUTcomes) team will be led by Prof Vanessa Raymont with Dementias Platform UK researchers from the Universities of Oxford and Cambridge. They will test multiple existing and novel blood tests, looking at a range of types of dementia.

The ADAPT team (Alzheimer's disease Diagnosis and Plasma pTau217) will be led by Professor Jonathan Schott and Dr Ashvini Keshavan at University College London. They will focus on the most promising biomarker for Alzheimer’s disease, called p-tau217.  Both teams conducting this biomarker research will look at whether the blood tests can help detect these diseases at various stages.

Why we need to improve dementia diagnosis

Current figures estimate that more than a third of people over 65 who are living with dementia in England go undiagnosed.

The diagnostic tests currently available such as brain scans and lumbar punctures, are time-consuming, uncomfortable, and are not uniformly available to dementia services around the UK. 

We know that getting an accurate diagnosis takes far too long, with people waiting a year, on average, to see a clinician. And for people with young-onset dementia, it can take as long as four years.

This highlights an urgent need for the NHS to improve how it diagnoses people with symptoms of dementia. 

Importance of early diagnosis

Two treatments - lecanemab and donanemab – are finally on the horizon for people with early Alzheimer’s disease.

Preparing the NHS to make sure these drugs are available to all those who could benefit is now key. And that means accurately diagnosing people at the earliest stages.

The promise is clear. It could mean that when someone is referred to a clinic for diagnosis within the NHS, they will have rapid access to a simple, non-invasive, and inexpensive blood test, receiving the result within weeks. 

Diagnosing Alzheimer’s disease at its earliest stages would also allow people time to put in place support and care, take part in clinical trials and to access new treatments when they arrive. 

A 'new era' of dementia treatments

Dr Susan Kohlhaas, Executive Director of Research and Partnerships at Alzheimer’s Research UK, said:

We’re sitting on the cusp of a new era of dementia treatments.

"Doctors are likely going to see more people coming forward for a diagnosis. But the NHS doesn’t possess the required levels of diagnostic infrastructure to cope with this growing demand."

Fiona Carragher, Director of Research and Influencing, Alzheimer’s Society, added: “New drugs targeting early-stage Alzheimer’s disease are just around the corner.

"But without a diagnosis, people simply won’t be able to access them if they are approved. 

"This could absolutely revolutionise the way dementia is diagnosed." 

For blood tests to be used in clinical practice, they must reach the same level of sensitivity and specificity as spinal fluid tests that are currently used in the NHS.

The Blood Biomarker Challenge will begin to build the evidence needed to show that blood testing for the diseases that cause dementia is accurate for patients with suspected dementia living in the UK. It is important to also ensure that this testing fits within the NHS Healthcare system.  

This article was first published in 2023 and most recently updated in November 2024.