by Annette Pinder

According to MedPage Today, the U.S. Food and Drug Administration (FDA) has approved the Elecsys pTau181 test, developed by Roche. The test is the first blood-based biomarker intended for use in primary care settings to evaluate indicators of Alzheimer’s disease and other causes of cognitive decline.

The Elecsys pTau181 test measures plasma levels of phosphorylated tau 181 (p-tau181), a key marker linked to amyloid plaque and tau buildup, which are the main signs of Alzheimer’s disease. The test is designed for adults aged 55 and older who show signs of cognitive decline. When used with other clinical assessments, the test helps clinicians rule out signs of Alzheimer’s.

According to Roche, the test could broaden access to early screening and help primary care providers make more accurate referrals, enabling neurologists to focus on patients most likely to need advanced evaluation and treatment.

FDA clearance of the test was supported by a multicenter clinical study involving 312 participants representing typical primary care populations. The results showed a 97.9% negative predictive value, indicating it effectively rules out Alzheimer’s disease in patients without amyloid pathology. This clearance aligns with recent Alzheimer’s Association guidelines recommending blood-based biomarker tests with at least 90% sensitivity and 75% specificity for initial patient assessment. After a positive test, additional testing such as a follow-up PET scan or cerebrospinal fluid analysis is recommended to confirm Alzheimer’s disease.

MedPage Today emphasizes that the test builds on the FDA’s previous approval of Lumipulse G pTau217/β-Amyloid 1-42 Plasma Ratio, designed for use in specialty care. This new development coincides with emerging Alzheimer’s treatments that underscore the vital need for early and precise diagnosis to identify patients who are eligible for therapy.