The test, developed by C2N Diagnostics and built on technology invented at Washington University School of Medicine in St. Louis, uses high-resolution mass spectrometry to quantify Alzheimer’s-related biomarkers from a single blood draw. FDA clearance means the test has demonstrated accuracy comparable to cerebrospinal fluid testing and PET brain imaging, even in patients with mild cognitive symptoms.
How the Alzheimer’s Blood Test Works
PrecivityAD2 measures the ratio of amyloid proteins Aβ42 and Aβ40 alongside two forms of tau protein — p-tau217 and total tau217 — in the blood. Together these biomarkers signal the presence of amyloid pathology, a hallmark feature of Alzheimer’s disease. Unlike immunoassay-based blood tests already cleared by the FDA, PrecivityAD2 relies on mass spectrometry to deliver quantitative measurements rather than qualitative readings.
Previous validation studies showed the test can identify Alzheimer’s-related amyloid pathology with more than 90% accuracy. That performance places it on par with invasive screening methods such as lumbar punctures and PET scans, which have long been the clinical standard but carry cost, accessibility, and patient comfort barriers.
Why Early Diagnosis Matters Now
The timing of the FDA clearance is significant. The first disease-modifying treatments capable of slowing Alzheimer’s progression have recently reached patients, and clinical evidence indicates these therapies work best when started early in the disease course. A reliable blood test widens the funnel of patients who can be evaluated quickly and routed into appropriate care.
Before clearance, physicians could already order PrecivityAD2 for patients with mild cognitive symptoms. FDA approval changes the commercial trajectory: C2N Diagnostics can now market the test broadly to clinicians and health systems that rely on FDA review as a quality benchmark. Clearance is also expected to facilitate insurance coverage, which would reduce out-of-pocket costs and broaden access beyond specialized memory clinics.
Research Roots at Washington University
The foundational technology was developed by a WashU Medicine team co-led by Randall J. Bateman, the Charles F. and Joanne Knight Distinguished Professor of Neurology, and David M. Holtzman, the Barbara Burton and Reuben M. Morriss III Distinguished Professor in the Department of Neurology. The two researchers pioneered stable isotope-linked kinetics, or SILK, approaches to study how amyloid-beta is produced and cleared in the brain and cerebrospinal fluid. That work underpinned the blood-based biomarker technology now cleared by the FDA.
Bateman and Holtzman co-founded C2N Diagnostics in 2007 and worked with the WashU Office of Technology Management to patent components of the blood test. C2N holds exclusive commercial license rights to those patents and has continued an expanded research collaboration with WashU Medicine to accelerate commercialization.
“The PrecivityAD2 test provides an accurate and reliable way to detect the presence of brain amyloid plaques associated with Alzheimer’s disease pathology based on a single blood draw,” Bateman said. “With FDA clearance, this innovation can reach more patients, increasing early and accurate diagnoses for people who are seeking causes of cognitive symptoms such as memory loss. With faster diagnosis, patients can receive earlier treatment, when treatments are most effective.”
Holtzman framed the clearance as a broader milestone. “Achieving FDA clearance of the PrecivityAD2 blood test is a key milestone in our mission to transform the diagnosis and management of Alzheimer’s disease on a path toward finding a cure,” he said. “This accomplishment reflects the unwavering, yearslong commitment of everyone on our team and the team at C2N Diagnostics to delivering innovative solutions that improve lives.”
What Happens Next
Broad uptake of PrecivityAD2 will depend on how quickly insurers adopt coverage policies following FDA clearance and how health systems integrate blood-based biomarker testing into cognitive evaluation pathways. Watch for real-world accuracy data as the test moves beyond validation cohorts into diverse clinical populations, and for C2N’s expanded St. Louis headquarters in the Cortex Innovation District to scale manufacturing and distribution. Longer term, the test’s mass spectrometry platform could anchor additional Alzheimer’s diagnostics as investigational drugs in the pipeline advance toward approval.
— Aisha Mensah, health desk, AXO News