New FDA-Cleared Blood Test Could Make Alzheimer’s Detection Easier

The PrecivityAD2 blood test measures Alzheimer’s-related amyloid and tau proteins and showed 91% accuracy in an independent validation study.

Diagnosing Alzheimer’s disease has often required memory and cognitive tests followed by brain scans or spinal fluid testing to determine whether the disease is behind a patient’s symptoms.
The FDA-approved blood test PrecivityAD2, developed using technology from Washington University School of Medicine in St. Louis, offers a less invasive way to detect Alzheimer’s-related changes in adults as young as 40 with signs of cognitive impairment. (1^✔ ✔Trusted Source
FDA clears blood test to aid evaluation for Alzheimer’s disease

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The test measures specific Alzheimer’s-related proteins from a single blood sample.

While it does not replace a full clinical evaluation, it could give doctors a faster and simpler way to determine whether Alzheimer’s disease is contributing to a patient’s cognitive symptoms, including in settings where access to specialized memory-care services may be limited.

What Does PrecivityAD2 Look for in the Blood?

PrecivityAD2 does not detect Alzheimer’s disease directly. Instead, it looks for proteins linked to the changes caused by the disease in the brain.

The test uses high-resolution mass spectrometry, a highly precise laboratory method, to measure two groups of proteins:

• Amyloid beta proteins (Aβ42 and Aβ40): These can build up in the brain and form amyloid plaques.
• Tau proteins (p-tau217 and total tau217): These are linked to the formation of tau tangles inside brain cells.

Amyloid plaques and tau tangles are key biological features of Alzheimer’s disease.

PrecivityAD2 combines measurements of these proteins into a single score that estimates the likelihood of amyloid plaques being present in the brain.

Unlike some earlier blood tests that focused on a single protein, PrecivityAD2 measures both amyloid and tau markers together.

According to researchers, this approach can detect amyloid pathology with more than 90% accuracy, with performance comparable to tests such as spinal fluid analysis or PET brain scans, including in people with mild symptoms.

How Accurate Is the PrecivityAD2 Blood Test?

To find out how reliably PrecivityAD2 identifies Alzheimer’s-related amyloid buildup, researchers tested the blood test in an independent group of 191 people with mild cognitive impairment or dementia. (3^✔ ✔Trusted Source
Independent validation of the PrecivityAD2â„¢ blood test to identify presence or absence of brain amyloid pathology in individuals with cognitive impairment

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They compared the blood test results with amyloid PET scans, which were used as the reference for whether brain amyloid pathology was present.

The results showed that the test performed consistently well:

The two markers pointed in the same direction in 73% of participants, and accuracy reached 94% in this group.

When the markers disagreed, accuracy fell to 81%.

Overall, the findings were consistent with earlier validation results, although the researchers said larger and more diverse studies are still needed.

The test could help doctors identify Alzheimer’s-related amyloid changes through a less invasive blood test, but it is designed to support, not replace, a full clinical evaluation.

Can a Blood Test Help Primary Care Doctors Diagnose Alzheimer’s?

PrecivityAD2 may help bring more accurate Alzheimer’s assessments into primary care, where many patients are first evaluated for memory problems.

A real-world Swedish study involving 1,310 patients and 165 doctors looked at how physicians’ diagnoses changed after they received the blood test results. The results showed a clear improvement:(4^✔ ✔Trusted Source
Alzheimer’s Blood Test Could Bring Highly Accurate Diagnosis into Everyday Clinical Care

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• Specialists: Accuracy increased from 74% to 89%
• Primary care doctors: Accuracy increased from 65% to 93%
• In a direct comparison after seeing the blood test results, primary care doctors and specialists achieved around 90% accuracy

The test was particularly helpful when doctors needed to rule out Alzheimer’s disease. Among primary care doctors, the proportion willing to rule out Alzheimer’s after a negative result increased from 12.9% to 25%.

The blood test also changed clinical decisions. Primary care doctors changed their diagnosis in 30% of patients, while treatment plans, referrals, or decisions about further testing changed in about half of cases.

However, the findings do not mean that a blood test can replace specialist evaluation. A negative Alzheimer’s blood test may help doctors look for other causes of memory problems. while patients with concerning symptoms may still need specialist assessment and additional testing.

This makes the real significance of PrecivityAD2 clearer: it could give primary care doctors a much more reliable tool for deciding whether Alzheimer’s is likely and whether a patient needs further specialist evaluation.

Who Can Get the PrecivityAD2 Blood Test, and How Is Alzheimer’s Disease Diagnosed?

PrecivityAD2 is FDA-cleared for adults aged 40 and older who have signs or symptoms of cognitive impairment. It is not intended as a routine screening test for people who have no symptoms.

The test is designed to help doctors determine whether Alzheimer’s-related changes may be behind a patient’s cognitive symptoms, including in people who develop symptoms at a younger age.

However, PrecivityAD2 cannot diagnose Alzheimer’s disease by itself. Its results are interpreted alongside the patient’s symptoms, medical history, cognitive assessment, and other clinical findings.

In general, diagnosing Alzheimer’s disease may involve several steps:(5^✔ ✔Trusted Source
Is There a Test for Alzheimer’s? Blood Tests & More

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1. Cognitive assessment: Tests such as the MMSE or MoCA evaluate memory, thinking and other cognitive abilities.
2. Blood testing: Blood tests may be used to detect biomarkers associated with Alzheimer’s disease, providing additional evidence about possible underlying disease-related changes.
3. Further testing when needed: Doctors may recommend amyloid PET imaging or cerebrospinal fluid analysis to provide additional or confirmatory evidence, depending on the individual patient and clinical situation.

Thus, blood testing is one part of the broader Alzheimer’s diagnostic process in general, rather than all of these steps being part of the PrecivityAD2 test itself.

A Step Closer to Earlier Alzheimer’s Detection

FDA clearance could help lower barriers to blood-based Alzheimer’s testing, including by potentially improving insurance coverage. More accessible testing may help patients get answers sooner—and, importantly, identify Alzheimer’s earlier when newer treatments may have the greatest chance to slow disease progression.

References:

1. FDA clears blood test to aid evaluation for Alzheimer’s disease – (https://medicine.washu.edu/news/fda-clears-blood-test-to-aid-evaluation-for-alzheimers-disease/)
2. Alzheimer’s Association Statement on FDA Clearance of PrecivityAD2 Blood Test for Alzheimer’s Diagnosis in Adults as Young as 40 – (https://www.alz.org/news/2026/fda-clearance-precivityad2-blood-test-alzheimers)
3. Independent validation of the PrecivityAD2™ blood test to identify presence or absence of brain amyloid pathology in individuals with cognitive impairment – (https://www.nature.com/articles/s44400-025-00026-y)
4. Alzheimer’s Blood Test Could Bring Highly Accurate Diagnosis into Everyday Clinical Care – (https://aaic.alz.org/releases-2026/alzheimers-blood-test-accurate-diagnosis-pcp.asp)
5. Is There a Test for Alzheimer’s? Blood Tests & More – (https://scienceinsights.org/is-there-a-test-for-alzheimers-blood-tests-more/)

Source-Medindia