According to C2N Diagnostics, the third FDA-cleared Alzheimer's blood biomarker test is PrecivityAD2, cleared on Aug. 20, 2026 C2N announcement.
A blood biomarker test measures blood proteins tied to Alzheimer's brain changes to help doctors evaluate memory symptoms. This briefing is for primary care patients with thinking or memory concerns. It explains what the test does, how well it worked, and what to discuss with your doctor.
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 FDA — Use this primary source to verify the official announcement.
- Read the official guidance from C2N — Use this primary source to verify the official guidance.
Table of Contents
- What are the three cleared tests?
- How does PrecivityAD2 work?
- How accurate was it in testing?
- Could you get it through primary care?
- What should you ask and do next?
What are the three cleared tests?
The first two clearances came before PrecivityAD2. According to the FDA and Roche, they were Fujirebio's Lumipulse G pTau217/β-Amyloid 1-42 Plasma Ratio on May 16, 2025, and Roche's Elecsys pTau181 on Oct. 13, 2025 FDA clearance notice. Fujirebio's test was cleared for adults 55 and older with symptoms.
PrecivityAD2 reaches younger symptomatic adults. According to the Alzheimer's Association, it is indicated for adults age 40 and older with signs or symptoms of cognitive impairment. That lower age start matters for primary care. Younger patients with memory complaints now have a cleared blood option tied to formal evaluation.
How does PrecivityAD2 work?
The test uses high-resolution mass spectrometry in a laboratory. Mass spectrometry is a method that sorts tiny protein pieces by weight to measure them precisely. It measures two signals in plasma, the Aβ42/40 ratio and %p-tau217.
Aβ42/40 reflects amyloid protein balance, and %p-tau217 reflects tau protein altered at one site. The lab combines both results into an Amyloid Probability Score 2 from 0 to 100. A higher score means brain amyloid buildup is more likely.
How accurate was it in testing?
According to NeurologyLive, a 1,142-person study compared the blood result with amyloid PET scans or spinal-fluid testing NeurologyLive report. A positive result had 97.6% positive predictive value, and a negative result had 93.1% negative predictive value. Predictive value describes trust in that result for tested patients.
Positive predictive value means how often a positive call matched PET or spinal-fluid amyloid. The middle range was less firm. About 17.3% of participants received an intermediate "likely positive" result with only 77.3% positive predictive value. Those patients may still need PET or spinal-fluid testing for confirmation.
Could you get it through primary care?
The test fits a narrow group, not everyone worried about memory. Check these points with your clinician: According to Patient Care Online, the test is not a screening or stand-alone diagnostic and must be used with clinical assessment Patient Care Online report.
Your visit should still include history, medicines review, thinking tests, and other causes of symptoms. For primary-care patients, the FDA-cleared kit is expected later in 2026 while C2N's CLIA laboratory version remains available. A JAMA study of more than 1,200 primary- and specialty-care patients reported over 90% accuracy outperforming standard clinical evaluation.
- age 40 or older
- signs or symptoms of cognitive impairment, such as repeated memory lapses or confusion
- evaluation by a professional experienced in cognitive-impairment assessment
What should you ask and do next?
Ask whether a blood biomarker result would change your care plan. Some patients need referral for PET, spinal tap, counseling, or treatment review. Bring a symptom timeline, medicine and supplement list, sleep and mood changes, and a family member who sees daily function.
Ask what score range the lab reports, what follow-up each range triggers, and how long results take. If your result is intermediate or positive, ask which confirmatory test your clinic uses and what it costs. Bring a list of medicines, sleep changes, and examples of memory lapses to that visit.
