PrecivityAD2, made by C2N Diagnostics, became the third FDA-cleared blood test for Alzheimer's disease biomarkers on August 20, 2026. It uses a standard blood draw to help doctors evaluate adults 40 and older who already have cognitive symptoms, including mild cognitive impairment, for the amyloid plaques associated with Alzheimer's, according to C2N Diagnostics' announcement. The clearance matters most for people already in a diagnostic workup for memory or thinking changes. It does not replace a neurologist's evaluation, but it can cut down on how often a person needs a PET scan or spinal tap just to find out whether amyloid is present.
Medical information disclaimer: This article is for general educational purposes only and does not provide medical advice, diagnosis, or treatment. Always consult a physician or other qualified health professional about symptoms, medications, tests, or treatment decisions.
Official resources:
- Read the official guidance from Alz — Use this primary source to verify the official guidance.
- Read the official guidance from Practicalneurology — Use this primary source to verify the official guidance.
Table of Contents
- What PrecivityAD2 Actually Measures
- Why "Third" and "Fourth" Both Matter Right Now
- Who Qualifies, and Why the Age 40 Cutoff Is New
- What the Clearance Does Not Do
- What This Means Day-to-Day for Someone With Mild Cognitive Impairment
- Frequently Asked Questions
What PrecivityAD2 Actually Measures
PrecivityAD2 runs a blood sample through high-resolution mass spectrometry to measure two sets of proteins: amyloid-beta peptides (Aβ42/40) and tau peptides (p-tau217/np-tau217). The lab combines these ratios into a single score called the Amyloid Probability Score 2, or APS2, which estimates how likely it is that a person's brain has amyloid plaques, according to C2N Diagnostics and Practical Neurology. Amyloid plaques are one of the two hallmark brain changes tied to Alzheimer's disease, alongside tau tangles.
Measuring both amyloid and tau markers in one blood draw is what separates PrecivityAD2 from a single-marker test. In C2N's validation study of 1,142 people, a positive PrecivityAD2 result matched amyloid PET or spinal fluid testing 97.6% of the time, and a negative result matched 93.1% of the time, according to C2N's press release. Those numbers describe how often the blood test agreed with the more invasive standard, not how often it is right about every possible case.
Why "Third" and "Fourth" Both Matter Right Now
The Alzheimer's Association counts PrecivityAD2 as the third FDA-cleared blood-based biomarker test for Alzheimer's, after Fujirebio's Lumipulse in May 2025 and Roche's Elecsys pTau181 in October 2025, according to the Alzheimer's Association. Four days after PrecivityAD2's clearance, Roche's Elecsys pTau217 became the fourth, cleared August 24, 2026, as a single-marker test to rule amyloid pathology in or out in adults 55 and older, according to the Alzheimer's Association. For a reader tracking this space, the distinction is practical.
PrecivityAD2 combines amyloid and tau markers into one probability score and is cleared down to age 40. Elecsys pTau217 uses one marker, is cleared starting at age 55, and is framed as a rule-in/rule-out tool rather than a probability estimate. A person asking a doctor about "the new Alzheimer's blood test" should confirm which one is being discussed, since the age cutoffs and intended use differ.
Who Qualifies, and Why the Age 40 Cutoff Is New
PrecivityAD2 is cleared for adults 40 and older who already show signs or symptoms of cognitive impairment, which includes mild cognitive impairment, according to C2N Diagnostics. That makes it the first FDA-cleared Alzheimer's blood test authorized for patients as young as 40; the earlier cleared tests targeted symptomatic adults 55 and up, according to NeurologyLive. This lower age floor is relevant for a specific group: people with early-onset symptoms or a family history of early-onset Alzheimer's, who previously had no FDA-cleared blood option and had to go straight to PET imaging or a spinal tap to get an amyloid answer.
- A person qualifies for PrecivityAD2 if they are 40 or older and already have a doctor-identified sign of cognitive impairment, such as diagnosed mild cognitive impairment.
- The test is not intended for someone with no symptoms who simply wants to know their Alzheimer's risk.
- A positive or negative APS2 score is meant to be interpreted by the ordering clinician alongside cognitive testing, medical history, and other exam findings.
What the Clearance Does Not Do
C2N and multiple outlets covering the clearance are explicit that PrecivityAD2 aids diagnosis as part of a full clinical evaluation. It is not cleared for population screening and not cleared as a standalone diagnostic test for Alzheimer's disease, according to Practical Neurology.
That means a positive result does not, by itself, confirm an Alzheimer's diagnosis, and a negative result does not rule it out on its own. The test answers one specific question — is amyloid pathology likely present — and a doctor still has to combine that answer with cognitive testing, symptom history, and often additional evaluation before reaching a diagnosis.
What This Means Day-to-Day for Someone With Mild Cognitive Impairment
The Alzheimer's Drug Discovery Foundation frames the practical impact simply: a blood draw that can support, not replace, a dementia workup, potentially reducing how often a person needs a costlier or more invasive amyloid PET scan or spinal tap just to get an initial read on amyloid status, according to the Alzheimer's Drug Discovery Foundation. For someone already diagnosed with mild cognitive impairment, that can mean an earlier, cheaper first step in sorting out whether amyloid is a likely contributor before moving to imaging or spinal fluid testing. The FDA-cleared version of PrecivityAD2 was expected to become commercially available later in 2026, while C2N's existing CLIA-validated lab version continued to be offered through its own clinical laboratory in the meantime, according to C2N Diagnostics.
- Ask the ordering doctor whether they are using the newly FDA-cleared version or C2N's existing lab-run version, since availability and insurance handling can differ between the two.
- Expect the result framed as a probability score, not a yes/no diagnosis.
- Expect it paired with cognitive testing and clinical history, not used in place of them.
Frequently Asked Questions
Can someone get PrecivityAD2 without any memory symptoms, just to check their risk?
No. It is cleared only for adults 40 and older who already show signs or symptoms of cognitive impairment, not for screening people without symptoms, according to C2N Diagnostics.
Does a positive PrecivityAD2 result mean someone has Alzheimer's disease?
No. It estimates the likelihood of amyloid plaques, which is one factor a doctor weighs alongside cognitive testing and clinical history before making a diagnosis, according to Practical Neurology.
How is PrecivityAD2 different from Roche's Elecsys pTau217, cleared days later?
PrecivityAD2 combines amyloid and tau markers into one probability score and is cleared from age 40; Elecsys pTau217 uses a single marker to rule amyloid in or out and is cleared from age 55, according to the Alzheimer's Association.
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