The FDA cleared C2N Diagnostics' PrecivityAD2 in August 2026, a blood test that estimates the likelihood of Alzheimer's-associated amyloid plaques in symptomatic adults 40 and older. If you have new memory symptoms, the news does not make this a routine screening test or a stand-alone Alzheimer's diagnosis. The test may help a qualified clinician evaluate whether Alzheimer's-related brain changes are present. Your symptoms, clinical assessment, result category, and possible follow-up testing still matter.
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:
- Explore the official data from FDA — Use this primary source to review the underlying data.
- Read the official guidance from Precivityad — Use this primary source to verify the official guidance.
Table of Contents
- What did the FDA clearance establish?
- Who is the test for?
- What does PrecivityAD2 measure?
- How should the accuracy numbers be understood?
- What are the important limits and next steps?
What did the FDA clearance establish?
The FDA's device database lists precivityad2 under 510(k) number K253240 and records it as "substantially equivalent." That confirms the 2026 clearance described in the title, according to the FDA's PrecivityAD2 device record. C2N described PrecivityAD2 as the first FDA-cleared Alzheimer's blood test for symptomatic adults as young as 40. Clearance establishes a regulated use for the device; it does not establish that every positive result is Alzheimer's disease.
Who is the test for?
The cleared test is intended for adults 40 and older who have signs or symptoms of cognitive impairment. They must be undergoing evaluation for Alzheimer's disease or other possible causes of cognitive decline. PrecivityAD2 is not intended to screen people without symptoms.
It must accompany an assessment by a professional experienced in cognitive impairment, as C2N explains in its FDA-clearance announcement and intended-use description. A person with new memory problems should therefore start with a clinician-led evaluation, not a test order in isolation. The practical question is whether this test would clarify that evaluation and change the next step.
What does PrecivityAD2 measure?
PrecivityAD2 measures amyloid-beta 42/40 and percent p-tau217 in blood. These measures are combined into a proprietary score from 0 to 100 called the Amyloid Probability Score 2. The score estimates the likelihood that amyloid plaques associated with Alzheimer's disease are present in the brain.
It does not, by itself, establish that Alzheimer's disease is causing a person's symptoms. Result wording also matters. The validation study reported Negative, Positive, and an intermediate category called Likely Positive; those categories do not carry the same degree of certainty.
How should the accuracy numbers be understood?
C2N's clinical-validation study included 1,142 people with symptoms of cognitive decline. Results were compared with amyloid PET imaging or cerebrospinal-fluid biomarkers. In that population, 97.6% of Positive results agreed with a positive reference finding.
Among Negative results, 93.1% agreed with a negative reference finding. These figures describe performance in the studied population, not a guarantee for any individual. Likely Positive results occurred in 17.3% of participants and had a lower positive predictive value of 77.3%. That difference may affect whether a clinician recommends further confirmation before making treatment or care decisions.
What are the important limits and next steps?
False-positive and false-negative results can occur. Mayo Clinic Laboratories also notes that earlier clinical data came predominantly from White U.S. patients with mild cognitive impairment or early dementia, which limits how confidently the findings apply across all populations.
Evidence is insufficient for repeated testing to track biomarker changes or treatment response, according to the Mayo Clinic Laboratories test catalog. Availability requires another check. When C2N announced the clearance, it expected the FDA-cleared version to become available later in 2026, while its existing CLIA-validated laboratory offering remained available. Before testing, ask: Do not assume that any PrecivityAD2 order currently being offered is automatically the newly cleared version; confirm the exact test with the ordering clinician and laboratory.
- Which version of PrecivityAD2 would the laboratory perform?
- Is that version the FDA-cleared device or the existing laboratory offering?
- How would each possible result change the evaluation?
- Would a Positive or Likely Positive result require confirmation?
- What follow-up would be appropriate if the result is Negative but symptoms continue?
