AAIC 2026 findings show a blood test helped primary-care doctors diagnose Alzheimer's almost as accurately as dementia specialists. The test, C2N PrecivityAD2, measures Alzheimer's-related proteins in blood to estimate amyloid buildup in the brain. The evidence comes from a prospective study in Sweden. According to the Alzheimer's Association, neurologist Sebastian Palmqvist led the study of 1,310 patients with mild cognitive impairment or dementia evaluated by 165 physicians.
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 accurate were primary-care doctors with it?
- What changed in care after the result?
- Can you ask for this test now?
What does the test measure?
PrecivityAD2 measures the plasma amyloid-beta 42/40 ratio and phosphorylated tau called p-tau217. Those two blood markers feed into a score called APS2, or amyloid probability score. Washington University School of Medicine describes APS2 as an estimate of the likelihood of brain amyloid in its summary of the test.
High APS2 points toward amyloid buildup linked to Alzheimer's. Low APS2 points away from Alzheimer's. Doctors still pair the score with memory testing, history, and exams.
How accurate were primary-care doctors with it?
Before seeing blood results, primary-care doctors were right about 65% of the time. After seeing results, accuracy rose to about 93%, near specialists at 94%. Medscape reported that jump from 65% to 93% in its AAIC conference report.
Against amyloid confirmation testing, both primary-care doctors and specialists reached about 90% accuracy after disclosure. The test was strongest for ruling out Alzheimer's in primary care. That means a negative result let doctors confidently look for other causes.
What changed in care after the result?
Doctors changed the diagnosis in about one-third of patients after reviewing the blood score. They also changed planned management, referrals, or further workup in over half to more than 60% of cases. Those changes matter because treatment paths differ sharply.
A positive score can speed referral to dementia care and discussion of Alzheimer's drugs. A negative score can redirect care toward vascular disease, depression, sleep apnea, thyroid problems, or medication effects. Families get a clearer basis for safety planning and follow-up.
Can you ask for this test now?
The FDA cleared PrecivityAD2 on Aug. 20, 2026 to aid amyloid detection in symptomatic adults age 40 and older. NeurologyLive, reporting the FDA action, notes it is an aid rather than a standalone diagnosis in its clearance report.
Primary-care use still calls for follow-up testing and clinical judgment. The Sweden-only cohort may not fully reflect U.S. primary-care patients, and AAIC presentations await full peer-reviewed publication.
- Bring specific memory examples, onset timing, and current drugs to the visit
- Ask whether a blood amyloid test fits your symptoms and age group
- Ask what positive, negative, and borderline results would change next
- Confirm insurance coverage, lab used, and plans for referral or repeat testing
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