Dementia stands as the UK's leading cause of death, claiming over 75,000 lives annually, yet diagnosis often occurs only when symptoms become severe. However, a groundbreaking development could soon change this landscape. A new range of blood tests is currently undergoing trials, aiming to detect Alzheimer's disease—the most common form of dementia—decades before any symptoms manifest.
Early Detection for Better Outcomes
The primary hope is that these tests will identify the disease early enough to allow for lifestyle interventions, such as regular exercise and healthy eating, alongside targeted pharmaceutical treatments. In the absence of a cure, many scientists believe that early intervention represents the most promising strategy for combating Alzheimer's. With nearly one million people in the UK living with dementia, recent statistics reveal it causes more deaths than cancer or cardiovascular disease, often due to complications like pneumonia or swallowing difficulties stemming from a weakened immune system.
The Challenge of Late Diagnosis
Late diagnosis remains a significant issue, with one in four individuals waiting two years or more to seek medical help for dementia symptoms. Many mistakenly attribute signs like forgetfulness or confusion to normal ageing. Currently, doctors diagnose Alzheimer's using memory and cognitive function tests, along with MRI and PET scans to detect brain plaques—protein deposits associated with the disease. The new blood tests could accelerate this process by years, offering a more efficient diagnostic tool.
Innovative Testing Methods
Most of these tests involve drawing blood from a vein in the arm, but researchers are also developing a finger-prick test similar to those used by diabetes patients for glucose monitoring. This method would allow samples to be collected at home and sent to a laboratory for analysis. A team at Northwestern University in the US has made a critical discovery, identifying toxic proteins known as ACU193+ in the brain. These proteins appear to play a key role in the inflammation and cell damage characteristic of early-stage Alzheimer's.
Reporting their findings in the journal Alzheimer's & Dementia, the team noted that these proteins can be detected in the blood up to 20 years before symptoms emerge. Professor Richard Silverman, a senior author of the study, emphasised the importance of early treatment, stating that by the time symptoms appear, significant neurodegeneration has already occurred. He highlighted the goal of combining better early diagnostics with drugs that could halt the disease progression.
Current and Emerging Treatments
Existing medications, such as cholinesterase inhibitors like Aricept, have been used for years to boost acetylcholine activity in the brain, easing symptoms and improving quality of life, though they do not offer a cure. Newer drugs, including lecanemab and donanemab, can slow disease progression in early stages but are not yet approved for NHS use due to limited benefits relative to costs and potential side-effects like brain bleeds and swelling.
In a promising development, the Northwestern team has also found that a drug called NU-9, currently used for motor neurone disease, can deactivate the toxic ACU193+ proteins in mice. This raises hopes that it might prevent or delay the onset of Alzheimer's in humans.
Advancements in Biomarker Detection
Another blood test, the Fujirebio Lumipulse assay, has been used on approximately 1,000 people at University College Hospital in London. This test searches for a protein called pTau217, which indicates the presence of Alzheimer's hallmarks like tau tangles and amyloid plaques in the brain. Professor Jonathan Schott, involved in research backed by UK dementia charities, described pTau217 as one of the most promising biomarkers, with tests so sensitive they can detect concentrations as low as one part per billion.
To illustrate this sensitivity, Professor Schott explained that if a grain of salt were thrown into an Olympic-sized swimming pool, these tests would detect it. He is currently leading a clinical trial in memory clinics, aiming to provide evidence for the National Institute for Health and Care Excellence to make such tests routinely available on the NHS.
Future Prospects and Challenges
Dr. Richard Oakley, associate director of research and innovation at Alzheimer's Society, acknowledged that routine use of blood tests like those from Northwestern University is still some way off. However, he emphasised their potential to transform Alzheimer's diagnosis, noting that current diagnostic processes are too slow, and one in three people with dementia in the UK lack a diagnosis. With new treatments on the horizon, early and accurate diagnosis must become a priority to improve outcomes for patients.
