PrecivityAD2 is a blood test that helps doctors estimate amyloid buildup in adults age 40 and older with memory symptoms. In a 2026 Alzheimer's assessment, it works as an aid to exams and cognitive testing, not as a diagnosis by itself.
Amyloid means clumps of protein linked to Alzheimer's disease. According to C2N Diagnostics in its FDA clearance announcement, the test is cleared for symptomatic adults age 40 and older. It is the first cleared blood test down to age 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.
Table of Contents
- What the blood test measures
- How well does the score predict amyloid?
- Why it cannot diagnose Alzheimer's alone
- How to use it at your memory visit
What the blood test measures
Mayo Clinic Laboratories explains in its test catalog entry that the test uses high-resolution mass spectrometry to measure two blood markers. One is the Aβ42/40 ratio, a balance of amyloid fragments. The other is percent p-tau217, a modified tau protein linked to amyloid buildup.
The software combines both results into an Amyloid Probability Score 2 from 0 to 100. A higher score means a higher likelihood of brain amyloid. Your doctor reads it with symptoms, exam findings, and cognitive scores.
How well does the score predict amyloid?
In a 1,142-person study of people with symptoms, NeurologyLive reported in its clearance report that a positive score correctly predicted amyloid in 97.6% of cases. A negative score correctly ruled out amyloid in 93.1% of cases when checked against PET scans or spinal fluid tests.
The same NeurologyLive report notes about 17.3% of people had an intermediate likely-positive result. In that group, only 77.3% actually had amyloid, so doctors use judgment and may order PET or spinal fluid testing.
Why it cannot diagnose Alzheimer's alone
The Alzheimer's Association states the FDA label positions the test strictly as an adjunct to standard workup. It is not for population screening and cannot diagnose Alzheimer's alone.
The 2025 Alzheimer's Association guideline, summarized by Healio, recommends blood biomarkers only in specialized memory-care workups. It sets about 90% sensitivity and specificity thresholds for triage versus replacing PET or spinal fluid tests.
How to use it at your memory visit
Practical Neurology reports the blood result can speed amyloid confirmation, treatment-eligibility decisions, and trial referral. It does not replace medical history, cognitive testing, and clinician interpretation.
Ask your clinic these practical questions: Bring a symptom timeline, medication list, and a family member who knows your daily changes. If your score falls in the intermediate band, plan for added testing before any treatment choice.
- Do my symptoms qualify me for testing at age 40 or older?
- Will the score change our need for PET or spinal fluid testing?
- How will the result affect treatment or trial options?
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