Two cleared tests, one goal
A new generation of blood tests is moving Alzheimer's diagnosis out of specialist clinics. The FDA cleared Roche and Eli Lilly's Elecsys pTau217 plasma test as the first single-biomarker assay that can both rule in and rule out amyloid pathology in adults aged 55 and older who show signs of the disease. Fujirebio's Lumipulse G pTau217 and beta-amyloid 1-42 plasma ratio test came earlier, and its ratio measurement was validated in a multi-center study of 499 plasma samples from cognitively impaired adults.
Why a blood draw matters
Until recently, confirming amyloid plaques required a PET scan or a lumbar puncture. Both are expensive, slow and unavailable in many regions, which helps explain why researchers estimate that about 75 percent of people living with dementia never receive a diagnosis. A blood test that costs far less and needs only a standard draw could be ordered in primary care, where most patients with memory complaints are first seen. That matters more as anti-amyloid therapies reach the market and depend on early confirmation of amyloid status.
Doctors urge caution
Not everyone is convinced that broad screening is ready. A viewpoint published in JAMA by Dr. Heather Whitson and colleagues noted that wider use of plasma biomarkers could lead to testing in people without symptoms, unnecessary treatment and confusion about what a positive result means for a patient who feels well. Physicians also point out that the tests indicate the presence of amyloid, not the certainty of disease. The practical question now is how health systems will pay for the tests, who should order them, and how results are explained to patients and families before treatment decisions are made.
Some hospital systems have already added plasma pTau217 testing to memory clinic pathways, pairing it with cognitive assessment and imaging when a result is borderline. Reimbursement is not settled, and coverage decisions will shape how quickly the tests spread beyond academic medical centers.