PrecivityAD2 is a blood test that helps detect amyloid pathology in symptomatic adults age 40 and older. Memory clinic patients avoid overreading the headline by treating it as an aid inside a full evaluation, not a stand-alone diagnosis. Amyloid pathology means abnormal amyloid protein buildup linked to Alzheimer's disease. The test combines blood markers into an Amyloid Probability Score 2 from 0 to 100.
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 test measures
- Why a positive result is not a diagnosis
- What changes for patients in their 40s and 50s
- How to use the result at a memory clinic visit
What the test measures
PrecivityAD2 measures plasma Aβ42/40 and p-tau217/np-tau217 ratios with immunoprecipitation plus mass spectrometry. The two ratios are combined into the 0-to-100 score. Patient Care Online reported the August 2026 FDA clearance for symptomatic adults age 40 and older in its FDA clearance report.
In a 1,142-person symptomatic group checked against amyloid PET or spinal-fluid testing, a positive result had 97.6% positive predictive value. A negative result had 93.1% negative predictive value. Those numbers apply to people who already have cognitive symptoms and receive clinical assessment.
Why a positive result is not a diagnosis
FDA labeling bars screening and stand-alone diagnosis without clinical assessment. About 17.3% of validation participants received an intermediate "likely positive" result with only 77.3% predictive value. That middle group matters for memory clinic decisions. A high score supports further workup, while an intermediate score leaves more doubt.
Neither result alone establishes Alzheimer's dementia. The Alzheimer's Association's July 2025 guideline limits blood-biomarker use to patients with objective impairment seen in specialty or memory care, as described in the Association guideline summary. A test meeting 90% sensitivity plus 75% specificity qualifies only for triage. Only 90% sensitivity plus 90% specificity can substitute for PET or spinal-fluid testing.
What changes for patients in their 40s and 50s
Younger-onset Alzheimer's means disease affecting people under age 65, with many patients in their 40s and 50s. The Alzheimer's Association explains that age definition in its younger-onset overview. A 40-year test floor widens who can receive aided evaluation.
It does not lower the age cutoff for younger-onset disease or make every memory lapse in midlife Alzheimer's. For a 47-year-old with measured thinking changes, the test may enter the workup. For a 47-year-old with normal exam scores and no objective impairment, the guideline path does not support it.
How to use the result at a memory clinic visit
WashU Medicine notes that patients with cognitive symptoms still need full evaluation because an amyloid blood result alone does not establish dementia and often needs confirmation or specialist interpretation, as explained in its evaluation guidance. Bring a symptom timeline, current medicines, sleep and mood history, and a family member who sees daily function.
Ask how the score fits cognition, exam findings, and other causes of impairment. Ask whether PET, spinal-fluid testing, or referral is needed next.
- Confirm objective impairment was documented before testing
- Ask which score range resulted: negative, intermediate, or positive
- Ask what confirms or revises the result in your case
- Leave with a written next-step plan, not only a score
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