C2N Diagnostics said in its company announcement that the FDA cleared PrecivityAD2 on August 20, 2026. PrecivityAD2 is a blood test that aids Alzheimer's evaluation in adults 40 and older with memory or thinking symptoms.
It is not a screening test for people without symptoms. It must pair with an expert clinical assessment of cognitive impairment. For primary care patients, the shift is practical: a blood draw can guide next steps.
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 Alz — Use this primary source to verify the official guidance.
Table of Contents
- Who is the test for?
- What does the blood sample measure?
- How accurate are positive, negative, and unclear results?
- What changes at a primary care visit?
Who is the test for?
The test is for adults 40 and older who already have signs of cognitive impairment. The Alzheimer's Association notes in its clearance summary that PrecivityAD2 is the first FDA-cleared Alzheimer's blood test for symptomatic adults as young as 40. Earlier clearances such as Lumipulse and Roche Elecsys tests were limited to ages 55 and older.
It is not for routine screening or home use. It is not a stand-alone diagnosis. A professional experienced in cognitive care must interpret it with exams and history.
- Age 40 or older
- Signs or symptoms of cognitive impairment
- Evaluation by an experienced clinician
What does the blood sample measure?
The test uses high-resolution mass spectrometry to measure two blood ratios. One is the Aβ42/40 ratio. The other is the p-tau217/np-tau217 ratio.
Patient Care Online explains in its test description that the two ratios combine into an Amyloid Probability Score 2 from 0 to 100. A higher score signals a higher likelihood of amyloid pathology. The clinician reads that score with symptoms, exam results, and history.
How accurate are positive, negative, and unclear results?
In a 1,142-person study against amyloid PET or spinal-fluid testing, a positive result had 97.6% positive predictive value for ruling in amyloid pathology. A negative result had 93.1% negative predictive value for ruling out amyloid pathology. An intermediate "likely positive" result occurred in 17.3% of participants and was correct only 77.3% of the time, according to Patient Care Online in its coverage of the validation study.
A clear positive strongly supports further Alzheimer's-focused care. A clear negative points away from amyloid as the cause. An intermediate result needs more review and often more testing.
What changes at a primary care visit?
A clinician can order one blood draw during workup of memory concerns. That result helps decide on specialist referral or further testing. It offers a simpler first step than starting with PET imaging or lumbar puncture.
- Describe specific memory or thinking changes and when they started
- Bring medicines, health history, and a family observer when possible
- Ask whether a blood test fits your symptoms and exam findings
- Ask what a positive, negative, or intermediate score would change for you
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