Primary-care doctors who used the C2N PrecivityAD2 blood test reached about 90% diagnostic accuracy, matching dementia specialists. Next comes careful rollout in primary care under accuracy standards for triage use, prevention-trial selection, and monitoring choices. An Alzheimer's blood test measures blood markers tied to disease biology, including p-tau217, a phosphorylated tau protein linked to Alzheimer's changes. AAIC 2026 was held July 12-15 in London and online with more than 11,000 registrants, and the Alzheimer's Association reports that primary-care diagnosis and future risk prediction were central topics.
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 did the new primary-care study test?
- How much did accuracy improve?
- Who can avoid extra testing right now?
- What does a high marker mean for future risk?
What did the new primary-care study test?
Sebastian Palmqvist of Lund University led a Swedish real-world study with 1,310 patients and 165 physicians. The test was C2N PrecivityAD2, which measures p-tau217 and amyloid-beta ratios. The Alzheimer's Association reports these design details for the primary-care population.
In practice, the doctor orders a blood draw during a memory-symptom workup. The result sits beside history, exam, and basic cognitive testing. It does not replace clinical judgment.
How much did accuracy improve?
Before testing, primary-care accuracy was 65%. After seeing blood results, it rose to 93%, versus 94% for dementia specialists, according to the Alzheimer's Association in its detailed primary-care results.
Decisions changed often. Physicians changed the diagnosis in about one-third of patients. They changed planned care, referrals, or workup in more than half after reviewing the result.
Who can avoid extra testing right now?
The test helped most by ruling out Alzheimer's disease. Symptomatic patients who test negative can often avoid specialty referral and invasive PET or spinal-tap confirmation.
That spares time, travel, cost, and discomfort. Cleared use remains narrow. SOVIDAY, summarizing the FDA, explains the clearance in its summary of the FDA clearance:.
- FDA cleared Fujirebio Lumipulse G pTau217/B-Amyloid 1-42 on May 16, 2025, for adults 55 and older with cognitive symptoms in specialty care.
- Reported agreement versus PET or spinal fluid was 91.7% positive and 97.3% negative.
- Cleared tests are aids only, not standalone diagnosis and not screening of people without symptoms.
- Many commercial tests do not meet guideline thresholds, so test choice matters.
What does a high marker mean for future risk?
Among 2,684 cognitively unimpaired adults averaging age 70, very high plasma p-tau217 carried about 38% risk of impairment within 5 years and 78% within 10 years. The finding was published simultaneously in JAMA, according to the Alzheimer's Association in its risk-prediction summary. That result does not set a personal timeline.
It helps researchers enrich prevention trials and helps clinicians plan follow-up. What comes next is implementation under the Alzheimer's Association's first 2025 biomarker guideline, which requires at least 90% sensitivity and 75% specificity for triage use, as described by Patient Care Online in its report on the guideline. Bring a symptom timeline, medication list, and a family observer to that primary-care visit.
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