PrecivityAD2 is a blood test for adults age 40 and older with signs of cognitive impairment who are being evaluated for Alzheimer's or other decline. For younger-onset concerns, it offers a measurable amyloid-likelihood score to review with a clinician, not a stand-alone diagnosis.
PrecivityAD2 measures plasma markers and combines them into the Amyloid Probability Score 2, from 0 to 100. Younger-onset Alzheimer's means symptoms before age 65, most often first noticed at 45 to 64. The test is used with clinical assessment, so the visit conversation matters as much as the number.
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 does the test measure?
- How well does it match PET or spinal fluid?
- Does younger age change the workup?
- What questions should you bring to the appointment?
What does the test measure?
PrecivityAD2 quantifies plasma Aβ42/Aβ40 and p-tau217/np-tau217 using immunoprecipitation plus LC-MS/MS, according to Mayo Clinic Laboratories in the test catalog. Those ratios reflect amyloid-related processes linked to Alzheimer's biology. The lab then calculates APS2 to estimate the likelihood of brain amyloid.
A low score suggests lower amyloid likelihood, while a higher score suggests higher likelihood. The score does not grade memory loss or identify another cause of decline. Ask your clinician what range your result falls in and what it adds to your exam, history, and cognitive testing.
How well does it match PET or spinal fluid?
In a 2024 prospective JAMA study of 1,213 symptomatic patients, APS2 agreed with amyloid PET or spinal-fluid results in about 90% of cases. C2N Diagnostics summarized that finding as 88% to 92% accuracy, better than standard workup without biomarkers, in the coverage announcement. That level matters because blood tests still miss some cases.
The Alzheimer's Association's first blood-biomarker guideline, released July 29, 2025, sets performance tiers for specialty care. According to the Association in the guideline release, tests with at least 90% sensitivity and 75% specificity can triage impairment, while tests reaching 90% on both measures may substitute for PET or spinal-fluid testing. Ask whether your center treats PrecivityAD2 as triage or as a replacement in your situation.
Does younger age change the workup?
Younger or early-onset Alzheimer's is diagnosed with the same cognitive, biomarker, PET or spinal-fluid, and exclusion workup as late-onset disease. Age changes the differential because thyroid disease, mood disorders, sleep apnea, medication effects, and other neurologic conditions can mimic early decline. A blood result never removes the need to rule those out.
C2N Diagnostics reports FDA clearance on Aug. 20, 2026 for adults age 40 and older with cognitive signs who are undergoing evaluation, in the FDA clearance notice. That age range includes many people worried about younger-onset symptoms. Ask whether your clinic follows the same confirmation path for patients under 65 as for older adults.
What questions should you bring to the appointment?
Bring notes on when symptoms started, work impact, family history, medications, sleep, mood, and any prior test scores. Ask if the blood test fits your case, who interprets it, how long results take, and what a positive or negative result would change next.
PrecivityAD2 is not cleared as a screening or stand-alone test and requires symptoms plus evaluation by a clinician experienced in cognitive impairment. Ask for the plan in writing, including the next test, the decision it will inform, and whom to call with new symptoms.
- Will a positive APS2 need PET or spinal-fluid confirmation before any treatment referral?
- Does this result support referral for anti-amyloid therapy evaluation, or point elsewhere?
- What follow-up is planned if APS2 is borderline or conflicts with my exam?
- What does my insurance cover, and what prior authorization is needed? Anthem began medical-policy coverage for eligible members Oct. 1, 2026.
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