The third FDA-cleared Alzheimer's blood biomarker test in 2026 is C2N Diagnostics' PrecivityAD2, cleared Aug. 20, 2026 for amyloid pathology.
For primary-care patients, the key interpretation question is what a negative, likely-positive, or positive score means alongside symptoms and clinical assessment. Amyloid pathology means abnormal buildup of amyloid plaques in the brain associated with Alzheimer's disease. According to the Alzheimer's Association, the clearance covers PrecivityAD2 as a blood-based marker of that pathology Alzheimer's Association announcement.
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:
- Check eligibility on C2N’s official study page — Use this page to check the study’s participation requirements.
- Read the official guidance from Alz — Use this primary source to verify the official guidance.
Table of Contents
- What does the score measure?
- Who qualifies for testing?
- What do the three result bands mean?
- Do age and other conditions affect results?
What does the score measure?
According to Patient Care Online, the test uses mass spectrometry to measure plasma Aβ42/40 and p-tau217/np-tau217 Patient Care Online report. It combines those results into Amyloid Probability Score 2, scaled 0 to 100. A higher score signals higher likelihood of amyloid pathology.
Think of the score as a likelihood signal, not a stand-alone diagnosis. A low score points away from amyloid buildup. A high score points toward it and shapes next steps.
Who qualifies for testing?
The test is cleared for adults age 40 and older with signs or symptoms of cognitive impairment. That age cutoff reaches younger symptomatic patients than the two earlier cleared tests.
NeurologyLive reports the expanded eligibility. It is not cleared for screening people without symptoms. It is also not cleared for diagnosis by blood result alone.
- Age 40 or older
- Signs or symptoms of cognitive impairment
- Assessment by a clinician experienced in cognitive impairment
What do the three result bands mean?
According to NeurologyLive, a study of 1,142 symptomatic adults compared blood results with amyloid PET or spinal-fluid testing NeurologyLive report. Positive results had 97.6% positive predictive value. Negative results had 93.1% negative predictive value. About 17.3% of patients fell into a middle band called likely positive, with 77.3% predictive value.
That middle band carries more uncertainty than a clear positive or negative. Patients in that band most need a direct question about confirmatory testing. Under the Alzheimer's Association July 2025 guideline, tests meeting triage thresholds use negatives to rule out pathology while positives need PET or spinal-fluid confirmation guideline summary. A positive blood result starts the workup. It does not finish it.
Do age and other conditions affect results?
Performance stayed consistent across age groups in the clearance study. It also stayed consistent across 12 prespecified chronic conditions. Those included chronic kidney disease, atrial fibrillation, and diabetes.
Consistency does not remove the need for clinical context. Memory history, exam findings, medications, and other causes of impairment still shape meaning. C2N said the FDA-cleared version would arrive later in 2026 while its laboratory-validated test remained available, so ask what version your clinic offers and what confirmation path it uses before you give blood.
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