Two Alzheimer’s breakthroughs could diagnose condition years earlier, experts say

New blood tests and brain scans could spot Alzheimer’s years before symptoms appear, researchers say.

The findings suggest signs of the disease could be picked up earlier, raising the prospect of earlier diagnosis and treatment for thousands of patients.

Experts said the results were encouraging, but cautioned that more research is needed before the approaches can be used routinely.

Published in two separate papers, the findings could also strengthen the case for NHS approval of two drugs that can slow the progression of Alzheimer’s if the disease is caught early.

In the first study, researchers found that proteins linked to dementia, known as biomarkers, could be detected in middle-aged adults through a simple blood test.

They analysed levels of amyloid-beta protein plaques and phosphorylated tau in blood samples from 1,350 adults in the US who did not have dementia.

The participants had an average age of 61.

Researchers found that those with higher levels of these biomarkers had worse cognitive performance, as well as declining memory function and slower ability to process information.

The researchers said: “These findings support the concept that Alzheimer’s disease begins decades before clinical symptoms emerge and highlight the potential value of plasma biomarkers for early detection in the general population.”

They added that identifying people with early Alzheimer’s disease could support research “aimed at delaying or preventing the onset of dementia.

A version of this type of test was approved by the Food and Drug Administration in the US in 2025, although it is not yet part of NHS care.

Experts believe the approval could help pave the way for similar tests to become available in Britain in future.

Experts not involved in the study welcomed the findings, while cautioning that further research is still needed.

Dr Richard Oakley, associate director of research and innovation at Alzheimer’s Society, said: “Blood-based biomarkers offer a promising, cost-effective and less invasive way of detecting Alzheimer’s disease so it’s encouraging to see momentum in this area.

Professor Paresh Malhotra, head of the division of neurology in the department of brain science at Imperial College London, said: “It is also critical that we keep in mind that having an abnormal blood test is not in itself a clinical diagnosis and does not mean that someone will inevitably get dementia.

“At the moment we only really understand what these tests mean when there is evidence of cognitive impairment, so they can be helpful where there has been a clinical assessment but we do not yet fully understand their implications when they have been done without any such assessment or in people where there is no objective evidence of cognitive difficulties.”

The results could also strengthen the case for manufacturers Eli Lilly and Eisai, which made donanemab and lecanemab respectively.

Both drugs were shown to delay progression from mild to moderate Alzheimer’s by up to six months in early, symptomatic Alzheimer’s and were licensed for use in the UK in 2024.

However, they were not made available on the NHS after the National Institute for Health and Care Excellence said their benefits were too small to justify the cost.

The decision was appealed by Eli Lilly and Eisai, but no final decision has yet been made.

The second study found that a new type of brain scan could detect tau proteins, another key Alzheimer’s biomarker, more effectively than current methods used in Europe and the US.

A study involving 682 participants from the US and Canada compared two types of PET brain scans, both of which use low levels of radiation to detect conditions such as cancer.

The experimental scan relied on a tracer – the technical name for the radioactive substance – called MK6240, whereas the established method employs a tracer known as Flortaucipir.

In cognitively healthy individuals, the newer tracer found more than twice as many early tau-positive cases compared to the standard scan.

It also picked up considerably greater levels of tau in those already displaying signs of cognitive decline.

The findings led researchers to conclude that existing brain scanning techniques may be overlooking a significant number of early tau accumulation cases associated with Alzheimer’s disease.

The study further underscores the promise of the newer tracer, which has yet to receive approval for routine clinical use in either the UK or the US.

The results were broadly welcomed by experts in the field

Roslyn Bill, professor of Biotechnology at Aston University, said ‘this work represents an important advance for the Alzheimer’s disease field’.

Tara Spires-Jones, professor of neurodegeneration at the University of Edinburgh, and division lead in the UK Dementia Research Institute, said: ‘These are both well conducted studies that advance what we know about detecting the early brain changes associated with Alzheimer’s disease.

“It is important to note that while these are important scientific findings that will be very useful for research and clinical trials, neither the blood test nor the brain scans investigated are available for routine clinical use in the UK.”