Dementia ranks as the leading cause of death in the UK, taking the lives of over 75,000 individuals annually. Its diagnosis often comes late, only when symptoms become significantly severe.

However, a groundbreaking development in medical research may soon change this. New blood tests are being trialed with the potential to detect Alzheimer’s disease, the most prevalent form of dementia, years before any symptoms manifest.

The goal is to identify the disease early enough to implement lifestyle changes—such as increasing physical activity and adopting a healthier diet—alongside specific medications to halt its progression. In the absence of a definitive cure, many researchers advocate that early intervention could be the most effective strategy against Alzheimer’s.

Currently, dementia affects nearly one million people in the UK, and it is responsible for more deaths than cancer or heart disease. This is often due to complications like pneumonia or swallowing difficulties, which arise from a weakened immune system.

A significant issue is the delay in diagnosis, as one in four individuals waits over two years to seek medical advice for dementia-related symptoms, mistaking them for natural signs of aging, such as memory lapses or confusion.

At present, Alzheimer’s diagnosis involves cognitive assessments and imaging techniques like MRI and PET scans to detect brain plaques, or protein build-ups. The introduction of these innovative blood tests could expedite this process significantly, offering a much earlier and potentially life-saving diagnosis.

Most tests currently involve taking samples from a blood vessel in the arm. But at least one team of researchers is working on a finger-prick test – similar to that used by diabetes patients to measure their blood glucose levels. The sample would be done at home and posted to a laboratory for analysis.

A team at Northwestern University in the US has identified for the first time the toxic proteins (called ACU193+) in the brain that seem to play a key role in the inflammation and cell damage that are hallmarks of early-stage Alzheimer’s.

New blood tests being trialled to detect Alzheimer’s disease decades before symptoms appear

Everyone experiences dementia differently. Use this checklist to help you make a note of your symptoms before you talk to your GP.

Reporting their findings in the journal Alzheimer’s & Dementia, the team said these proteins can be found in the blood 20 years before symptoms appear.

‘It’s important to be treated before symptoms appear because by then much neurodegeneration has already occurred,’ Richard

Silverman, a professor of chemistry at Northwestern and senior author of the study, told Good Health.

‘The promise of better early diagnostics before symptoms are apparent – combined with a drug that could stop the disease in its tracks – is the goal.’

Some drugs, such as cholinesterase inhibitors (e.g. Aricept) have been around for years and work by boosting the activity of acetylcholine, a chemical messenger in the brain vital for memory and learning. They can ease symptoms and improve quality of life, but they are not a cure.

Newer drugs, such as lecanemab and donanemab, can slow down the progression of the disease in the early stages, when symptoms have started to appear.

But they’re not approved for use on the NHS partly due to the benefits being too small to justify the cost and the potential side-effects, such as brain bleeds and swelling.

However, the Northwestern team that’s working on a blood test has also found a new drug called NU-9, already a treatment for motor neurone disease (an incurable illness leading to loss of muscle control), can turn off the toxic ACU193+ proteins in mice.

It is raising hopes that this drug could potentially prevent – or significantly delay – the onset of Alzheimer’s too.

Meanwhile, a second blood test – called the Fujirebio Lumipulse assay – has already been used on an estimated 1,000 people at University College Hospital in London by doctors searching for a protein called pTau217.

This protein can indicate the presence of hallmarks of Alzheimer’s disease in the brain, including tau tangles and amyloid plaques.

‘There are hundreds of potential biomarkers, but pTau217 is definitely one of the most promising,’ says Jonathan Schott, a professor of neurology at the University College London Institute of Neurology. He is involved in research on pTau217 as part of a programme backed by UK dementia charities to investigate potential blood tests.

He says some of the tests being developed are so sensitive they can detect one part per billion, or even lower, concentrations of specific Alzheimer’s proteins in the blood.

He told Good Health: ‘To give you some idea of how sensitive these tests are, if you threw a grain of salt into an Olympic-sized swimming pool, these tests would detect it.

‘We are now in the midst of conducting a clinical trial [on pTau217] in memory clinics, which we hope will provide the evidence that the National Institute for Health and Care Excellence needs to make these tests routinely available across the NHS.’

Dr Richard Oakley, associate director of research and innovation at Alzheimer’s Society, told Good Health that routine use of blood tests – such as that being developed at Northwestern University – is still some way off.

But he added: ‘They could transform how Alzheimer’s disease is diagnosed. Getting an accurate diagnosis currently takes far too long and one in three people in the UK with dementia do not have a diagnosis. With new treatments on the horizon, early and accurate diagnosis must be a priority.’