First Blood Test for Alzheimer Disease Diagnosis Cleared by FDA for Primary Care Use: Daily Dose

Patient Care brings primary care clinicians a lot of medical news every day—it’s easy to miss an important study. The Daily Dose provides a concise summary of one of the website's leading stories you may not have seen.

On October 13, 2025, we reported on the FDA clearance of the first blood-based biomarker specifically indicated to aid the initial assessment for Alzheimer disease (AD) and related causes of cognitive decline within the primary care setting.

The approval

The Elecsys pTau181 test (Roche) measures phosphorylated tau (pTau 181) protein in plasma—a key biomarker for AD, including amyloid plaque and tau aggregate presence—and is intended for adults aged 55 and older presenting with signs or symptoms of cognitive decline.

Clinical performance of the Elecsys pTau181 test was confirmed in a multicenter, noninterventional study involving 312 participants. In an early-disease, low-prevalence population reflective of primary-care settings, the test achieved a 97.9% negative predictive value (NPV) to rule out AD-associated amyloid pathology, according to Roche. The company emphasized that the result should always be interpreted alongside other clinical information.

The Elecsys pTau181 blood test offers primary care clinicians a minimally invasive way to rule out AD-related amyloid pathology, potentially reducing unnecessary PET or CSF testing and guiding referrals so that neurologists can focus on patients most likely to require advanced evaluation and treatment.

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