A simple blood test could detect Alzheimer's disease decades before symptoms appear, according to new research published in The Lancet. The study found that high levels of amyloid and tau proteins in the blood of people in their 60s were linked to poorer cognitive performance and faster decline in memory and processing speed over five years.
Researchers analysed blood samples from 1,350 dementia-free individuals in the US, average age 61, measuring two amyloid biomarkers and p-tau217. Of these, 86 had elevated levels, which correlated with measurable cognitive differences, suggesting the disease begins in midlife.
In a separate study, a new PET scan tracer called MK6240 detected tau tangles more than twice as effectively as the existing tracer Flortaucipir in early-stage regions. Flortaucipir is licensed in the UK but not routinely available on the NHS.
Dr Jacqui Hanley of Alzheimer's Research UK said the findings are exciting but stressed the need for larger, more diverse studies before routine use. She noted that accurate blood tests could improve diagnosis, as they are less invasive and more accessible than current methods like PET scans and lumbar punctures.
Dementia affects about one million people in the UK, with Alzheimer's accounting for 60–80% of cases. The number is expected to rise to 1.4 million by 2040.
