PrecivityAD2 is a blood test that helps identify brain amyloid in symptomatic adults evaluated for Alzheimer's disease. In 2026 it was cleared for ages 40 and older, and primary-care follow-up centers on clinical review, confirmation, and referral. Amyloid refers to protein buildup linked to Alzheimer's brain change. The test score supports, but does not replace, a clinician's assessment.
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.
Table of Contents
- What changed in 2026?
- How does the score work?
- How accurate is each result?
- What should happen next in primary care?
What changed in 2026?
On Aug. 20, 2026, FDA cleared C2N Diagnostics' PrecivityAD2 to aid identification of brain amyloid in symptomatic adults age 40 and older. According to the FDA clearance announcement from C2N Diagnostics, it was the first cleared blood test down to age 40 the FDA clearance announcement from C2N Diagnostics.
FixFirst Health places it as the third FDA-cleared Alzheimer's blood amyloid test, after tests limited to age 55 and older. The practical change is expanded younger-adult access, not a new use in healthy adults. The role did not change with expansion. It remains an aid used with clinical assessment, not screening or a standalone diagnosis.
How does the score work?
The test uses high-resolution mass spectrometry to measure two blood ratios: amyloid-beta 42/40 and phosphorylated-tau217 to non-phosphorylated-tau217. According to WashU Medicine, those results combine into an Amyloid Probability Score 2 WashU Medicine report on the clearance. The score is reported in three groups: Negative, Likely Positive, or Positive.
Negative suggests amyloid is less likely, Positive suggests it is more likely, and Likely Positive is intermediate. A clinician reads that group with history, exam, cognitive testing, and other possible causes. Blood alone does not settle the cause of symptoms.
How accurate is each result?
In 1,142 symptomatic adults compared with amyloid PET or spinal-fluid testing, a Positive result had 97.6% positive predictive value and a Negative result had 93.1% negative predictive value. According to NeurologyLive, 17.3% received intermediate Likely Positive results with only 77.3% predictive value NeurologyLive coverage of the validation data. Positive and Negative results were strong but not perfect.
The intermediate group was common enough to matter for planning. For that reason, Likely Positive needs careful next steps rather than quick reassurance or quick action. Confirmation and specialty input matter most in that group.
What should happen next in primary care?
The blood result starts a clinical path, not treatment by itself. According to the MLO clinical-pathway discussion, practical next steps pair the blood result with history, cognitive testing, and other causes, then prioritize PET or spinal-fluid confirmation, specialty referral, and treatment-care planning MLO discussion of the diagnostic pathway.
C2N Diagnostics states the test is for professionals experienced in cognitive impairment, not for asymptomatic people, patients under 40, or tracking change over time. Availability also matters because the FDA-cleared kit version is expected later in 2026, while C2N continues its laboratory-developed version. Bring a symptom timeline, medicine list, and a family member to the follow-up visit.
- Review symptoms, onset, medicines, sleep, mood, and medical causes
- Complete formal cognitive testing and basic labs as indicated
- Discuss PET or spinal-fluid confirmation and neurology referral
- Plan safety, work, driving, support needs, and follow-up timing
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