The FDA has cleared PrecivityAD2, a blood test from C2N Diagnostics that helps detect the biology of Alzheimer’s disease — and it is authorized for adults with cognitive symptoms as young as 40.
Cleared on August 20, 2026, the test uses high-resolution mass spectrometry to measure specific beta-amyloid and tau protein fragments in blood, reporting an Aβ42/40 ratio and a %p-tau217 value that are combined into an amyloid probability score. Those markers reflect the amyloid plaques and tau changes that characterize Alzheimer’s.
Part of a bigger shift
PrecivityAD2 joins a rapidly growing field. The first US blood test to aid Alzheimer’s diagnosis (Fujirebio’s Lumipulse pTau217/beta-amyloid ratio) was cleared in 2025, and assays from Roche, C2N, Quanterix and ALZpath are now cleared, under review, or available through specialized labs. Until recently, confirming Alzheimer’s biology required a PET scan or a spinal tap — costly or invasive options that limited access.
Why it matters
Accurate, less-invasive testing matters more now that amyloid-targeting Alzheimer’s therapies are available and work best early. A blood test can help confirm whether memory symptoms are driven by Alzheimer’s pathology. Importantly, these tests are meant to aid diagnosis in people who already have symptoms, not to screen healthy people; results are interpreted by clinicians alongside other information.