C2N Diagnostics announced FDA clearance of PrecivityAD2 on Aug. 20, 2026 for adults 40 and older with signs of cognitive impairment, the company announcement. For memory-clinic patients, it aids evaluation of amyloid pathology alongside specialist assessment, not as a stand-alone dementia diagnosis.
Amyloid pathology means abnormal amyloid protein buildup linked to Alzheimer's disease. The test produces an Amyloid Probability Score 2 from 0 to 100. The main interpretation issue is what an intermediate likely-positive result means for follow-up testing.
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:
- Read the official guidance from C2N — Use this primary source to verify the official guidance.
- Check eligibility on Patientcareonline’s official study page — Use this page to check the study’s participation requirements.
Table of Contents
- Who should get this test?
- What does your APS2 score mean?
- Why does likely-positive cause confusion?
- When do you still need PET or spinal-fluid testing?
- How to confirm which test version you received
Who should get this test?
PrecivityAD2 is cleared only for people already showing cognitive signs or symptoms. It is not cleared for screening people without symptoms. Evaluation must be done with clinical assessment by a clinician experienced in cognitive impairment.
The Alzheimer's Association guideline limits blood-biomarker use to cognitively impaired patients seen in specialty or memory-clinic care when the result will change management. Pretest probability matters. That means your history, exam, and cognitive testing shape what the blood result means.
What does your APS2 score mean?
Patient Care Online reports the test uses high-resolution mass spectrometry to measure plasma Aβ42/40 and p-tau217 ratios, then combines them into APS2, the test description. Aβ42/40 is the ratio of two amyloid fragments in blood. P-tau217 is a phosphorylated tau marker linked to Alzheimer's changes.
A clearly positive score supports the presence of brain amyloid pathology. A clearly negative score argues against it. Neither result alone diagnoses dementia. The clinician weighs the score with symptoms, function, medications, and other causes.
Why does likely-positive cause confusion?
In a 1,142-person symptomatic validation group, a positive result had 97.6% positive predictive value and a negative result had 93.1% negative predictive value against amyloid PET scans or spinal-fluid markers, according to NeurologyLive, the validation summary. PET means a brain scan read for amyloid. Spinal-fluid markers come from cerebrospinal fluid testing.
About 17.3% of those patients received an intermediate likely-positive result with only 77.3% positive predictive value. That gap is the central memory-clinic question. A likely-positive result is less certain and often prompts discussion of confirmatory testing.
When do you still need PET or spinal-fluid testing?
Confirmatory testing is most relevant after a likely-positive result, when symptoms and blood result conflict, or when a treatment decision requires higher certainty. Anti-amyloid treatment, trial enrollment, and exclusion of other causes can raise the stakes. In those cases a specialist may order amyloid PET or cerebrospinal fluid analysis.
NeurologyLive reports performance stayed consistent across age groups and 12 chronic conditions including chronic kidney disease, atrial fibrillation, and diabetes. That consistency helps interpretation in older adults with multiple illnesses. It does not remove the need for clinical judgment about pretest probability and next steps. Bring these items to the visit:.
- current cognitive symptoms, onset, and functional change
- full medication, kidney, heart, and metabolic history
- prior brain imaging, lab work, and cognitive scores
- whether a positive amyloid finding would change care
How to confirm which test version you received
Ask the clinic whether you had the FDA-cleared PrecivityAD2 or C2N's laboratory-developed test. The cleared version was expected later in 2026 while the laboratory test remained available. Cutoffs, labeling, and intended use can differ.
Keep the exact test name, APS2 number, result category, and date in your record. Ask which cutoff the clinic used and whether PET or spinal-fluid confirmation is advised. That record prevents confusion if you seek a second opinion.
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