PrecivityAD2 is a blood test that helps clinicians check for amyloid pathology tied to Alzheimer's disease. For adults age 40 and older with new memory symptoms, it works only alongside a standard clinical assessment, not as a stand-alone screen.
The Alzheimer's Association reports FDA clearance on Aug. 20, 2026 for this use in its clearance announcement. The result adds biological information to history, thinking tests, and clinical judgment.
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
- Who can consider this test?
- What does the blood sample measure?
- How well does it match brain amyloid scans?
- Why must doctors interpret the score in context?
- What happens during evaluation?
Who can consider this test?
The cleared group is adults age 40 and older with signs or symptoms of cognitive impairment. That means new memory concerns that prompt a clinical visit, not routine testing without symptoms.
C2N Diagnostics states the test is indicated only with a standard workup by professionals experienced in cognitive-impairment evaluation. Readers can check these points before asking a clinician:.
- age 40 or older
- signs or symptoms of cognitive impairment
- access to follow-up evaluation and clinical judgment
What does the blood sample measure?
C2N Diagnostics says PrecivityAD2 uses high-resolution mass spectrometry to measure two plasma ratios: Aβ42/40 and p-tau217/np-tau217. These ratios are blood signals related to Alzheimer's-related protein changes.
The two results combine into an Amyloid Probability Score 2 from 0 to 100. A higher score means greater likelihood of amyloid pathology.
How well does it match brain amyloid scans?
A clinical validation study published in Alzheimer's & Dementia tested a prespecified APS2 cutoff of 47.5 in the journal validation report. Accuracy was 88% versus amyloid PET, with 88% sensitivity and 89% specificity.
A prospective JAMA study of more than 1,200 primary- and specialty-care patients was described in a BioSpace/C2N partnership release. It reported 91% positive predictive value and 92% negative predictive value with one cutoff, rising to about 95% each with two cutoffs.
Why must doctors interpret the score in context?
Mayo Clinic Laboratories states APS2 must be interpreted with other patient information in its test catalog. A positive value alone does not rule in Alzheimer's disease, and a negative value alone does not rule it out.
That limit is why the test works as an adjunct. The clinician weighs symptoms, medical history, thinking tests, and sometimes added scans or spinal-fluid testing.
What happens during evaluation?
Medical News Today describes a practical path of one blood draw plus history, cognitive testing, and possible PET or spinal-fluid confirmation rather than starting with invasive testing. A reader with new memory symptoms can discuss that sequence with a clinician.
A Frontiers in Psychology review notes the 2024 Alzheimer's Association Workgroup criteria define Alzheimer's biologically and include accurate plasma p-tau217 as a Core 1 marker. Ask your clinician whether PET or spinal-fluid confirmation fits your case after the blood result.
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