PrecivityAD2 is a blood test that helps doctors check for amyloid pathology, the Alzheimer-related protein buildup in the brain. For memory-clinic patients in 2026, it works only as an add-on to a full clinical exam, not as a screening test or stand-alone diagnosis.
According to WashU Medicine, the FDA cleared it on Aug. 20, 2026 for adults age 40 and older with signs or symptoms of cognitive impairment the FDA clearance announcement. That age floor makes it the first cleared Alzheimer blood test available 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 does the blood draw measure?
- How accurate is it against PET or spinal fluid?
- Does other illness change the result?
- Who should get it, and who should not?
- How should patients compare blood, PET, and spinal-fluid testing?
What does the blood draw measure?
NeurologyLive describes PrecivityAD2 as a high-resolution mass spectrometry test. It measures the plasma amyloid-beta 42/40 ratio plus percent phosphorylated tau217.
Those two results combine into one Amyloid Probability Score 2. The report reads negative, positive, or likely positive. Likely positive signals an intermediate result that needs more clinical judgment.
How accurate is it against PET or spinal fluid?
NeurologyLive reports testing in 1,142 symptomatic adults against amyloid PET or cerebrospinal fluid the validation results summary. Positive results showed 97.6% positive predictive value and negative results showed 93.1% negative predictive value.
The likely-positive group covered 17.3% of patients and carried 77.3% predictive value. In practice, a clear negative lowers the odds of amyloid pathology and a clear positive raises them, while likely positive often points toward follow-up testing.
Does other illness change the result?
NeurologyLive reports that performance held across age groups and 12 common comorbidities. Those included chronic kidney disease, atrial fibrillation, and diabetes.
That stability matters for real workups. Older clinic patients often bring kidney, heart, or metabolic conditions to the visit. The finding supports using the blood check during routine impairment workups where those conditions appear.
Who should get it, and who should not?
Practical Neurology reports the test is cleared only as an adjunct with assessment by clinicians experienced in cognitive-impairment evaluation the adjunct-use notice. It is not cleared for screening people without symptoms or for diagnosis by itself.
Forbes via ApexNews notes the Alzheimer Association's July 2025 blood-biomarker guideline limits use to cognitively impaired patients seen in specialized memory care the guideline context. That guidance endorses tests with at least 90% sensitivity. Ask whether your clinic visit, symptoms, and exam fit that specialized-use setting.
How should patients compare blood, PET, and spinal-fluid testing?
WashU Medicine explains that living-person confirmation once relied on amyloid PET scan or spinal-tap fluid analysis. A validated blood draw now offers a less invasive first amyloid check before PET, fluid testing, or trial referral.
Use the blood result to plan the next step, not to replace the exam. A memory-clinic team pairs history, thinking tests, and daily-function review with the biomarker result.
- Clear negative blood result plus unclear exam: discuss watchful follow-up or whether PET or fluid testing is still warranted.
- Clear positive blood result: ask about diagnosis, care planning, support services, and treatment or trial eligibility.
- Likely-positive blood result: ask which confirmatory test fits your health, cost, travel, and timing.
- Any result: bring a symptom timeline, medication list, and a family member who sees daily changes.
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