FDA clears Alzheimer’s blood test for patients as young as 40

A vial of blood now carries part of the Alzheimer’s workup. The U.S. Food and Drug Administration has cleared C2N Diagnostics’ PrecivityAD2 for patients as young as 40 who show potential cognitive symptoms—the first FDA-cleared blood test for Alzheimer’s evaluation in people that young.

The test looks for amyloid and tau, proteins associated with Alzheimer’s disease, in a single blood draw. It uses high-resolution mass spectrometry to measure Aβ42 and Aβ40, plus forms of tau called p-tau217 and total tau217. Those measurements are combined into a result classified as negative, likely positive or positive for Alzheimer’s disease.

The clinical validation involved 1,142 symptomatic adults. PrecivityAD2 identified 97.6% of positive biomarkers, according to the reported study results, and its performance remained consistent in patients with chronic kidney disease and diabetes. The FDA clearance means the test can be marketed more broadly to clinicians and health systems.

That matters because Alzheimer’s-related changes can begin years before symptoms become obvious. Until blood-based tests became available, evaluation could involve brain imaging with a PET scan or a lumbar puncture to obtain cerebrospinal fluid. PrecivityAD2 does not turn a blood sample into a general health check: it is intended for people who already show some cognitive decline, and doctors are expected to interpret it with clinical history and other diagnostic information.

So what changes in practice? For a patient seeking an explanation for memory loss, the cleared test offers a less invasive route to biomarker information than a spinal tap, while earlier answers may help clinicians consider treatments sooner. The test was created from research by Randall J. Bateman and David M. Holtzman at Washington University School of Medicine in St. Louis, then developed and validated by C2N Diagnostics, a WashU startup co-founded by the researchers. Insurance coverage and affordability may improve with FDA clearance, but the sources do not provide a price or coverage timetable.