The FDA cleared PrecivityAD2, a blood test from C2N Diagnostics, on August 20, 2026, for adults 40 and older who have cognitive symptoms and are being evaluated for Alzheimer's disease. It is the first FDA-cleared blood test available to symptomatic adults as young as 40, and it works alongside a doctor's clinical evaluation rather than replacing one, according to C2N Diagnostics' announcement. For a reader noticing new memory problems in themselves or a family member, that clearance means a blood draw can now help a clinician decide, with more confidence, whether amyloid plaque buildup — a hallmark of Alzheimer's disease — is a likely explanation. It does not mean the test diagnoses Alzheimer's on its own, and it does not mean every primary care visit will offer it right away.
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 notice from Clpmag — Use this primary source to verify the official announcement.
- Explore the official data from Healthday — Use this primary source to review the underlying data.
Table of Contents
- Who the test is actually for
- What the blood test measures and how results are scored
- How accurate is a positive or negative result?
- Where this fits among existing Alzheimer's blood tests
- When and how a reader can actually get this test
Who the test is actually for
PrecivityAD2's FDA clearance covers adults aged 40 and older who are already showing signs or symptoms of cognitive impairment and are being evaluated for Alzheimer's disease or another cause of cognitive decline, according to C2N's press release. That is a narrower group than "everyone worried about memory loss." The clearance is not for general-population screening. A person with no symptoms who simply wants to know their future risk falls outside the cleared use, as the same release makes clear.
The test is meant to be ordered by a clinician already working through a cognitive evaluation, not requested as a standalone check. C2N also states the test is intended for use alongside a clinical assessment performed by clinicians experienced in evaluating cognitive impairment — not as a stand-alone diagnostic tool, per the company's announcement. A positive or negative result is one input a doctor weighs together with symptoms, history, and other exams.
What the blood test measures and how results are scored
The test uses high-resolution mass spectrometry to measure two ratios in plasma: amyloid-beta 42/40 and p-tau217/np-tau217. These are combined into a single Amyloid Probability Score 2 (APS2), ranging from 0 to 100, as described in trade coverage of the clearance.
The APS2 sorts into three categories: negative, likely positive, or positive. Each category reflects a different probability that amyloid plaque — the protein buildup associated with Alzheimer's disease — is present in the brain. These three categories do not carry equal certainty, which matters for how a reader should interpret a result.
How accurate is a positive or negative result?
In a validation study of 1,142 symptomatic adults, researchers compared PrecivityAD2 results against amyloid PET scans or spinal fluid (CSF) testing, the current reference standards for confirming amyloid pathology. A positive APS2 result had a 97.6% positive predictive value, meaning a positive result was confirmed by PET or CSF testing in the large majority of cases, according to validation data reported by HealthDay. A negative result performed almost as well, with a 93.1% negative predictive value in the same cohort. For most people who fall into the clear-negative or clear-positive range, the blood test aligns closely with more invasive or expensive confirmatory testing.
The middle category is where the test is weaker. "Likely positive" results occurred in 17.3% of the validation cohort, and this group's positive predictive value was only 77.3%, according to CLP Magazine's coverage of the clearance. Roughly one in four people with a "likely positive" result did not have confirmed amyloid pathology on follow-up testing. A reader who receives this particular result should expect a clinician to recommend additional testing rather than treat it as a final answer.
Where this fits among existing Alzheimer's blood tests
PrecivityAD2 is the second Alzheimer's blood test to receive FDA clearance, not the first overall. The FDA cleared Fujirebio Diagnostics' Lumipulse G pTau217/β-Amyloid 1-42 plasma ratio test roughly a year earlier, in 2025, according to trade press coverage of the clearance history.
PrecivityAD2's distinction is being the first cleared for symptomatic adults as young as 40, extending eligibility below the older age ranges typically associated with Alzheimer's evaluation. The Alzheimer's Drug Discovery Foundation, which helped fund early research behind the test's underlying biomarkers, described the clearance as a step forward for precision-medicine diagnostics in Alzheimer's care, in its own announcement.
When and how a reader can actually get this test
The newly FDA-cleared version of PrecivityAD2 is expected to become commercially available later in 2026. Until it does, C2N's existing CLIA-validated laboratory version remains available through the company's own clinical lab, according to C2N's press release.
A reader interested in the test now should ask their clinician which version is being ordered and whether it is the FDA-cleared version or the lab-developed one, since availability and ordering pathways differ between the two. A few practical points for someone considering this test: Exact FDA labeling language, formal warnings, and specific guidance for indeterminate results were not available in a located FDA.gov decision summary at the time of this reporting, according to 360Dx's coverage of the clearance. A clinician ordering the test can confirm those specifics directly with the reader.
- It requires a clinician's order as part of an active cognitive evaluation — it is not a direct-to-consumer purchase.
- It is relevant starting at age 40, younger than many people associate with Alzheimer's testing.
- A "likely positive" result carries more uncertainty than a clear positive or negative, and typically calls for further evaluation.
- The FDA-cleared version's commercial rollout is still pending as of this clearance; the lab-developed version remains the near-term option.
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