PrecivityAD2 is a blood test to help detect Alzheimer's-related amyloid buildup in adults age 40 and older who have cognitive symptoms. For younger-onset families in 2026, it offers a less invasive starting point to compare with brain scans and spinal-fluid tests. Younger-onset Alzheimer's means symptoms begin before age 65. It often looks different from late-life memory loss, so families need a clear testing plan with a memory specialist.
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 PrecivityAD2 measures
- Why the age-40 clearance matters
- How do blood tests compare with scans and spinal fluid?
- What to ask your memory clinic
What PrecivityAD2 measures
PrecivityAD2 measures two plasma ratios: A-beta 42/40 and phosphorylated tau 217 to non-phosphorylated tau 217. A-beta and tau are proteins linked to Alzheimer's pathology. Amyloid is the clumped form seen in Alzheimer's brains. The test combines both ratios in a proprietary formula.
The result is the Amyloid Probability Score 2, called APS2, from 0 to 100. Patient Care Online reported that the method uses high-resolution mass spectrometry to quantify both markers how the APS2 score is calculated. A higher APS2 means amyloid pathology is more likely. A lower score means it is less likely. The score does not diagnose Alzheimer's alone.
Why the age-40 clearance matters
On Aug. 20, 2026, the FDA cleared PrecivityAD2 to aid detection of amyloid pathology in symptomatic adults age 40 and older. Patient Care Online described it as the first cleared blood test reaching age 40 the FDA clearance report. That age cutoff matters for younger-onset families.
Younger-onset disease starts before 65 and makes up about 5%-6% of Alzheimer's cases. It often brings language, vision, behavior, or executive-function problems rather than classic forgetfulness. Clinicians may not suspect Alzheimer's in a 45- or 55-year-old. That mismatch often delays diagnosis. A cleared blood option at age 40 gives symptomatic younger adults a more accessible path to biomarker testing.
How do blood tests compare with scans and spinal fluid?
Families now choose among blood tests, amyloid PET scans, and cerebrospinal fluid testing. Spinal-fluid testing requires a lumbar puncture. PET requires a specialized imaging center and tracer. In the 1,142-person FDA-clearance validation, a positive PrecivityAD2 result had 97.6% positive predictive value against PET or spinal-fluid biomarkers.
A negative result had 93.1% negative predictive value. Predictive value means how often the blood result matched the PET or fluid result in that study group. An earlier study of 583 cognitively impaired patients found 88% agreement with amyloid PET and strong discrimination. Performance stayed similar by age, sex, ethnicity, and APOE4 status. Blood tests do not replace clinical judgment, and PET or spinal fluid may still be needed for unclear cases.
What to ask your memory clinic
FDA labeling requires PrecivityAD2 to be used with clinical assessment by clinicians experienced in evaluating cognitive impairment. Practical Neurology reports that it is not a screening test or stand-alone diagnosis the labeling summary. That means the clinic visit matters as much as the blood draw.
The Alzheimer's Association guideline says high-performing blood tests can substitute for PET or fluid tests in specialty memory care. Lower-performing tests need confirmatory testing. Bring these items to the appointment: Ask whether your center uses confirmatory PET or spinal-fluid testing after blood results.
- symptom timeline, including language, vision, behavior, and work changes
- current medicines, sleep, mood, and medical conditions that affect thinking
- family history and prior cognitive scores, imaging, or lab results
- list of testing options covered at your center, plus follow-up if results conflict
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