Dementia is the UK’s biggest killer, claiming more than 75,000 lives every year – but it’s often difficult to diagnose until symptoms are very pronounced.
However, that could soon change thanks to a revolutionary range of new blood tests being trialled to detect Alzheimer’s disease decades before symptoms appear.
The hope is the tests will catch the disease – which is the most common form of dementia – early enough that lifestyle changes, such as regular exercise and healthy eating alongside targeted drugs, can stop it. In the absence of a cure, some scientists think this type of early intervention is the best bet for combating Alzheimer’s.
Nearly one million people in the UK have dementia and, according to recent statistics, it causes more deaths than cancer or cardiovascular disease – usually from problems arising from a weakened immune system, such as pneumonia, or difficulty swallowing.
Late diagnosis is a big problem because one in four people wait two years or more to seek medical help for dementia symptoms – often assuming such issues, including forgetfulness or confusion, are simply due to ageing.
Doctors currently diagnose Alzheimer’s with memory and cognitive function tests, as well as MRI and PET scans to look for signs of plaques (protein deposits) in the brain. But the new wave of blood tests could speed up the process by years.
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.’
