A count nobody had a year ago. "Just over a year ago, there were no FDA-cleared blood tests for Alzheimer's and now we have three," said Isobel Coleman, CEO of the Alzheimer's Drug Discovery Foundation. The newest is C2N Diagnostics' PrecivityAD2, cleared August 20, 2026 for adults as young as 40 who are showing signs of cognitive impairment.
The age floor moved by fifteen years. Fujirebio's Lumipulse (cleared May 2025) and Roche's Elecsys pTau181 (cleared October 2025) both stop at age 55. PrecivityAD2 starts at 40. Younger-onset Alzheimer's is rarer but real, and until this clearance, a 45-year-old with genuine memory symptoms had no FDA-cleared blood test built for their age group.
Same biology, a different lab method. PrecivityAD2 runs on high-resolution mass spectrometry, measuring the ratio of amyloid beta 42 to 40 alongside p-tau217 to non-phosphorylated tau217. That is the same amyloid-and-tau biology the other two tests target, read through a different assay.
The validation numbers, not just the age headline. In a 1,142-subject study, a positive PrecivityAD2 result predicted amyloid pathology 97.6% of the time, and a negative result ruled it out 93.1% of the time. Those figures sit close to Lumipulse's 92% positive predictive value and Elecsys pTau181's 97.9% negative predictive value, in the range clinicians previously needed a PET scan or spinal tap to reach.
Symptoms are still the gate, for all three. PrecivityAD2 is cleared for use alongside standard clinical workup in patients already showing signs, symptoms, or complaints of cognitive decline: memory lapses, word-finding trouble, a family member pushing for answers. It is not cleared as a screening test or a stand-alone diagnostic for someone with no symptoms at a routine physical, the same limit that applies to Lumipulse and Elecsys pTau181.
Clearance changes who can access it, not who built it. C2N had already been running PrecivityAD2 as a lab-developed test before this. FDA clearance lets the company market it more broadly to clinicians and health systems, and it can make insurance coverage easier to get, the same practical shift that came with Roche's Elecsys clearance last year.
This is the third test in a fast-moving field. See what the other two FDA-cleared Alzheimer's blood tests do and where a primary care clinician can already order one.