Around one in 10 people in the UK aged 70 and over show Alzheimer’s-like changes in their brain, according to the most comprehensive real-world study yet of how common the disease’s biological markers are among older adults.
The findings suggest that more than one million people over 70 could meet the clinical criteria for new anti-amyloid treatments, far exceeding current NHS estimates of around 70,000 potential patients if funding were available.
Largest population study to date
The research, published on 17 December in the journal Nature, is the first population-based study to measure Alzheimer’s-related brain changes using blood biomarkers in a large, randomly selected group.
The study analysed blood samples from nearly 11,500 people and provides the clearest picture yet of how widespread Alzheimer’s-related changes are in the general population, rather than in patients already attending specialist clinics.
Researchers from King’s College London, Stavanger University Hospital and the University of Gothenburg led the study.
Blood test reveals hidden brain changes
The researchers used the p-tau217 blood test, which detects proteins associated with Alzheimer’s disease and was recently approved by regulators.
The test can identify disease-related changes years earlier than traditional diagnostic methods, offering the potential for earlier and more accurate detection.
However, the presence of these proteins does not amount to a diagnosis of dementia. The test shows biological changes linked to Alzheimer’s, not whether someone will go on to develop symptoms.
Far more people meet treatment criteria
The findings indicate that more than one million people over the age of 70 in the UK would meet the National Institute for Health and Care Excellence criteria for anti-amyloid therapy.
This contrasts sharply with NHS planning assumptions, which have previously estimated that around 70,000 people might be eligible if such treatments were funded.
Experts say the gap highlights the scale of the challenge facing the NHS if new Alzheimer’s drugs become more widely available.
Experts call findings a potential breakthrough
Alzheimer’s Research UK said the study could transform how the disease is detected and managed.
David Thomas, head of policy and public affairs at the charity, said high-quality population studies are essential to understanding how blood tests for Alzheimer’s could be used in everyday NHS care.
He said more evidence is needed before these tests can be rolled out clinically, but described the findings as a major step forward.
Challenging assumptions about dementia
The study also challenges long-standing assumptions about dementia, including the belief that Alzheimer’s disproportionately affects women.
By measuring brain changes directly rather than relying on diagnosed cases, the research suggests the biological risk is more evenly distributed across sexes than previously thought.
Professor Dag Aarsland, lead author and professor of old age psychiatry at King’s College London, said the findings represent a potential turning point in dementia research.
He said the study used a simple blood test to detect brain changes that contribute to cognitive impairment, at a time when ageing populations are placing growing pressure on health systems.
Limits of current NHS treatment
While the findings raise hopes for earlier diagnosis, experts caution that treatment options remain limited.
Anti-amyloid drugs are not currently available on the NHS due to their high cost and safety concerns, although several are being assessed internationally.
Professor Tara Spires-Jones, director of the Centre for Discovery Brain Sciences at the University of Edinburgh, said improved treatments over the next few years would require easy and affordable ways to identify people with amyloid in their brain.
She said blood-based tests could play a crucial role once therapies become safer and more cost-effective.
Early detection brings new dilemmas
Professor Eric Brunner of University College London said the study shows dementia research is entering a new era, where identifying people before symptoms appear is increasingly possible.
However, he warned that the sheer number of people with early Alzheimer’s changes means the NHS could not afford to treat everyone under current drug pricing models.
Age-based risk becomes clearer
The study provides the first real-life estimates of how Alzheimer’s-related brain changes increase with age.
Fewer than 8% of people in their 50s and 60s carried the marker, rising to just over a third of those in their 70s and around two-thirds of people aged over 90.
Growing UK dementia challenge
Nearly one million people in the UK currently live with dementia, with around one in 14 people aged 65 and over affected.
That figure is projected to rise to around 1.4 million by 2040 as the population ages.
The new findings suggest many more people may already have early Alzheimer’s-related brain changes long before a diagnosis, underscoring the scale of the challenge facing the NHS and social care system in the coming decades.
