A simple blood test measuring p-tau217 detects Alzheimer's disease with 90% accuracy up to 15 years before symptoms, at a fraction of PET scan costs.
Researchers at Lund University in Sweden have published results of a blood-based Alzheimer's diagnostic test that achieves 90% accuracy in detecting the disease up to 15 years before clinical symptoms manifest. The test, published in The Lancet Neurology, measures phosphorylated tau 217 (p-tau217) protein levels and could fundamentally change how the neurodegenerative disease is screened for and managed worldwide.
The BioFINDER-3 study enrolled 8,200 participants aged 50 to 80 across 14 countries. The blood test correctly identified Alzheimer's pathology with 90% sensitivity and 92% specificity when compared against gold-standard PET brain scans and cerebrospinal fluid biomarkers. Importantly, the test was equally accurate across diverse ethnic groups and ages.
Currently, Alzheimer's diagnosis relies on expensive PET scans costing $3,000 to $5,000 per session, or invasive lumbar punctures. The new blood test can be performed in any standard laboratory at an estimated cost of $200, making population-level screening feasible for the first time.
The timing of this diagnostic advance is particularly significant given the recent FDA approvals of anti-amyloid antibody therapies such as lecanemab and donanemab. These medications are most effective when administered early in the disease course, before extensive neuronal damage has occurred. A simple blood test that identifies at-risk individuals could dramatically expand the population eligible for early intervention.
Dr. Oskar Hansson, who led the study, emphasized that early detection without effective treatment would raise significant ethical concerns. However, with disease-modifying therapies now available, the calculus has shifted decisively in favor of screening. He noted that combining the blood test with lifestyle interventions such as exercise, cognitive training, and cardiovascular risk management could further improve outcomes.
The test is expected to receive CE marking in Europe and FDA clearance in the United States within the coming year. Several commercial laboratory networks have already begun validation studies in preparation for widespread clinical deployment.
Alzheimer's disease currently affects approximately 55 million people worldwide, a number projected to reach 139 million by 2050. Annual global costs of dementia care exceed $1.3 trillion. Early detection and intervention could substantially reduce this burden on patients, caregivers, and healthcare systems.