Alzheimer's disease more widespread in people over 85, first-of-its-kind study finds
Large study links age-related prevalence of ADNC with potential for scalable early detection through blood tests
An international, first‑of‑its‑kind study suggests Alzheimer's disease is more widespread among people older than 85 than previously estimated. By analyzing blood samples from more than 11,000 adults, researchers mapped the presence of Alzheimer’s disease neuropathological changes (ADNC) across age groups and educational levels. The study combined data from 11,486 blood samples from people over 57 in Norway and involved researchers from King’s College London, Stavanger University Hospital, and the University of Gothenburg.
Researchers measured proteins in the blood associated with cognitive impairment, finding that ADNC prevalence increased with age but was lower than earlier estimates in younger cohorts. The work provides a glimpse into how a blood-based signal could help identify dementia risk at scale.
Among those over 70, about 10% had pre‑clinical Alzheimer’s — a stage with no noticeable symptoms — while roughly 9.8% had Alzheimer’s dementia. In contrast, ADNC was present in fewer than 8% of people aged 65 to 69, increasing to 65.2% in patients over 90. The study also found that ADNC was more prevalent in individuals with lower educational attainment, hinting at how education may intersect with disease progression might influence risk or detection.
Dag Aarsland, a professor at King’s College London, said it is vital to detect signs of dementia at the earliest possible stages, and that the blood test appears to offer clarity at scale. He cautioned that the research is early but emphasized the potential of a scalable biomarker to guide diagnosis and treatment decisions.
Dr. Richard Oakley, from Alzheimer’s Society, called the findings the first time this type of data has been observed in such a large group of people, underscoring the value of broader screening approaches in understanding how the disease unfolds across the population.
The researchers also noted that more than one in ten people over the age of 70 would meet the criteria for drugs designed to slow the early stages of Alzheimer’s disease, highlighting the possible impact of identifying high‑risk individuals earlier. The study’s authors stressed that translating these biomarkers into routine clinical practice will require further validation, standardized testing protocols, and integration with existing care pathways. This work arrives as health groups advocate for greater awareness, screening options, and publicly accessible resources to support families facing memory loss.
Public health advocates and dementia charities emphasize that early detection can influence care planning, access to therapies, and participation in clinical trials. For those seeking confidential guidance, Alzheimer’s Society provides a dementia support line and a symptoms checker to help people spot signs and decide when to talk to a GP. In the United Kingdom, the charity’s helpline is available to help navigate next steps and available services.
Ultimately, researchers say the study’s findings could reshape how prevalence estimates are understood in older age groups and may inform future screening strategies as populations age. As scientists pursue validation and refinement of blood‑based biomarkers, the potential for earlier intervention and improved quality of life for people living with or at risk for dementia remains a major area of focus in health research.
