A landmark study has delivered a sobering new assessment of the scale of Alzheimer's disease among the UK's elderly population, suggesting it is significantly more widespread than prior estimates indicated.
Key Findings from a Pioneering Blood Test Study
Researchers from King's College London, the University of Gothenburg, and Stavanger University Hospital conducted a large-scale analysis of 11,486 blood samples from participants over the age of 57. The samples were part of the long-running Trondelag Health Study (HUNT) in Norway.
The team used a simple blood test to search for specific biomarkers – proteins linked to the development of cognitive impairment and Alzheimer's disease neuropathological changes (ADNC). These changes involve the build-up of harmful proteins in the brain, which lead to nerve cell death.
The analysis, published in December 2025, found that the frequency of these Alzheimer's-related brain changes increased sharply with age. While present in fewer than 8% of people aged 65-69, the prevalence jumped dramatically to 65.2% in individuals over the age of 90.
Stark Numbers Reveal Hidden Scale of the Disease
The study provided a detailed breakdown of the disease's presence in the over-70s age group, uncovering a significant hidden burden.
It found that 10% of people over 70 had symptomless, pre-clinical Alzheimer's disease. A further 9.8% were living with Alzheimer's dementia. Additionally, 10.4% were in the prodromal stage – the phase between pre-clinical and dementia where memory and thinking problems become noticeable.
Critically, the research concluded that more than one in 10 people (11%) over the age of 70 would meet the clinical criteria for new antibody treatments like lecanemab and donanemab. These drugs are designed to slow the progression of the disease in its early stages.
Implications for Diagnosis, Treatment, and the NHS
The findings have profound implications for healthcare policy and patient care in the UK. Dr Richard Oakley, Associate Director of Research and Innovation at Alzheimer's Society, called the data "a stark reminder of the scale of dementia." He emphasised that blood tests could transform diagnosis by being quicker, cheaper, and less invasive than current methods like PET scans or lumbar punctures.
However, access remains a significant hurdle. While licensed for use in the UK, the new antibody drugs are not currently available on the NHS. The spending watchdog NICE argued their benefits were "too small" to justify the high cost. Similarly, the blood tests used in the study are not yet available through the health service.
There is hope on the horizon. A major trial announced in September will recruit 1,100 people from memory clinics to investigate how effectively a blood test works within the NHS, with results expected in three years.
Professor Dag Aarsland of King's IoPPN stated, "If we are to meet this global challenge, it is vital that we are able to detect signs of dementia at the earliest possible stages. This blood test looks to be an effective means of providing that clarity at scale."
The study also noted a concerning link between education level and disease prevalence, finding ADNC was more common in individuals with lower educational attainment.
