FDA cleared C2N Diagnostics' PrecivityAD2 blood test on Aug. 20, 2026 for symptomatic adults age 40 and older. The test is established as a clinical aid for detecting amyloid pathology, while the exact cause of symptoms and next care steps still require a doctor's evaluation.
PrecivityAD2 is a blood test that measures Alzheimer's-related proteins to estimate the likelihood of amyloid plaques in the brain. Amyloid plaques are protein deposits linked to Alzheimer's disease. For younger-onset families, the clearance lowers the eligible age to 40.
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 C2N — Use this primary source to verify the official guidance.
- Read the official guidance from Medicalxpress — Use this primary source to verify the official guidance.
Table of Contents
- What FDA clearance allows
- How well does it rule amyloid in or out?
- Why starting at age 40 matters
- Where this test fits among other options
- Practical steps for families now
What FDA clearance allows
FDA clearance limits PrecivityAD2 to adults with signs of cognitive impairment who are undergoing evaluation. According to C2N Diagnostics, the test is not for screening or as a stand-alone diagnosis, and results must be used alongside clinical assessment C2N Diagnostics announcement.
The test uses high-resolution mass spectrometry to measure plasma Aβ42/40 and p-tau217/np-tau217 ratios. Those results are combined in an Amyloid Probability Score. According to C2N Diagnostics, that score signals the likelihood of amyloid pathology rather than giving an Alzheimer's diagnosis by itself C2N Diagnostics announcement.
How well does it rule amyloid in or out?
In a 1,142-person symptomatic validation cohort, PrecivityAD2 showed 97.6% positive predictive value for ruling in amyloid and 93.1% negative predictive value for ruling it out versus PET or CSF. HealthDay reported those results through Medical Xpress in September 2026 HealthDay report via Medical Xpress. High predictive values help doctors place a positive or negative result with more confidence.
A positive result still needs clinical context, and a negative result does not explain every cause of memory or thinking changes. About 17.3% of tested patients received an intermediate "likely positive" result with only about 77.3% predictive value. The Practical Guide for Neurologists notes that this middle group needs further workup rather than a firm answer neurologists' practical guide.
Why starting at age 40 matters
The age-40 indication matters because an estimated 200,000 Americans have younger-onset Alzheimer's under age 65. The Alzheimer's Association LEADS project describes this group as often misdiagnosed and underserved in research Alzheimer's Association LEADS page.
Prior cleared tests started at age 55, which left many younger symptomatic adults outside the labeled use. Families in their 40s and early 50s faced longer paths to testing, referral, and answers. The lower age cutoff gives doctors a cleared blood-test option during evaluation at 40 and older.
Where this test fits among other options
PrecivityAD2 is the third amyloid-pathology blood clearance. Earlier clearances were Fujirebio Lumipulse in May 2025 and Roche Elecsys pTau181 in October 2025, both for older symptomatic adults.
The main difference is eligibility and method, not a replacement for full care. PrecivityAD2 uses mass spectrometry and an Amyloid Probability Score for adults 40 and older with symptoms. A doctor still decides whether PET, spinal fluid testing, or other causes of impairment need review.
Practical steps for families now
Ask for an evaluation if thinking, memory, language, judgment, or daily function has changed. Bring examples, dates, medications, sleep changes, mood changes, and family history.
Ask whether the person meets the symptomatic-adult criteria for testing. C2N said the FDA-cleared kit would be available later in 2026. Families currently access only its CLIA laboratory-developed version through C2N's lab.
- Confirm cognitive symptoms are present and being evaluated
- Ask how results will be combined with exam, history, and other tests
- Ask what a negative, positive, or intermediate result would change
- Plan follow-up before testing, especially for an intermediate result
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