A groundbreaking study published in the Lancet suggests that Alzheimer's disease may be present in midlife, causing subtle memory problems decades before clinical symptoms emerge. Researchers have found that a simple blood test could detect biomarkers indicating the buildup of amyloid and tau proteins in the brain, which are hallmarks of the most common form of dementia.
Study Details
US researchers tested the blood of 1,350 individuals without dementia, with an average age of 61, for biomarkers associated with Alzheimer's. Among them, 86 participants showed high levels of these biomarkers. Crucially, these individuals also scored lower on cognitive tests measuring verbal memory and thinking speed, suggesting early cognitive decline.
Implications for Early Detection
Lead author Professor Kristine Yaffe from the University of California stated: “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.” She added that blood tests “could help target preventive strategies and clinical trials aimed at delaying or preventing the onset of dementia.”
Limitations and Ongoing Research
It remains uncertain whether participants with elevated biomarkers will eventually develop Alzheimer's. Scientists are still investigating the precise role of amyloid and tau protein tangles in the disease. These proteins are also present in some elderly individuals without dementia, complicating the picture.
Advances in Brain Imaging
A separate study in the Lancet explored a new brain scan method using a tracer called MK6240, which detected tau tangles more effectively than the existing agent Flortaucipir (Tauvid). In a study of 682 patients, MK6240 identified more than twice as many tau-positive cases in early-stage regions. Flortaucipir is licensed in the UK but not routinely used on the NHS.
Clinical Trials and Future Treatments
The NHS is recruiting for a £10 million clinical trial called the ‘Blood Biomarker Challenge’ project, funded by the People's Postcode Lottery. Meanwhile, drugs that could halt Alzheimer's progression are in development but must be administered in early stages to be effective.
Dr Jacqui Hanley, head of research funding at Alzheimer's Research UK, commented: “These two studies add to a growing body of evidence showing progress in detecting the biological changes linked to Alzheimer's disease much earlier in life... Being able to identify these changes sooner than we can now could be incredibly valuable.”
Approximately one million Britons have dementia, a figure expected to rise to 1.4 million by 2040. Alzheimer's accounts for 60-80% of cases. Professor Paresh Malhotra, head of neurology at Imperial College London, noted: “This study has used the new blood tests... in a relatively large number of people below the age where cognitive symptoms become most frequent. It adds to our knowledge about how many people will have abnormal Alzheimer’s blood results at this age.”
