Primary care may finally have an Alzheimer’s test of its own
Industry Buzz
By bringing Alzheimer’s blood-based biomarker testing into primary care, we can help patients and their clinicians get answers sooner to support them earlier in their journeys.
—Brad Moore, president and CEO of Roche Diagnostics North America
Until now, the pathway to confirming (or excluding) Alzheimer’s has involved a combination of imaging, cerebrospinal fluid (CSF) biomarkers, PET amyloid scans, and neuropsychological profiling.
But on October 13, the FDA cleared a new tool that may shift the early steps of that journey: Roche’s Elecsys pTau181 blood test. []
“By bringing Alzheimer’s blood-based biomarker testing into primary care, we can help patients and their clinicians get answers sooner to support them earlier in their journeys,” said Brad Moore, president and CEO of Roche Diagnostics North America. []
Read Next: Alzheimer’s starts in your 30s, says doc—here are 3 early blood markers that matterWhat the approval means (and doesn’t mean)
What it is: The Elecsys pTau181 test quantifies phosphorylated tau at threonine 181 in plasma. Higher levels of pTau181 are correlated with Alzheimer’s pathology. Compared to other recently cleared assays, this test offers a single-biomarker approach rather than a ratio (e.g. pTau217/amyloid-β). []
Intended use: Importantly, the test is not being marketed as a definitive Alzheimer’s diagnostic. Its role is explicitly as a “rule-out” tool in symptomatic patients 55 and older who are manifesting signs of cognitive decline. In other words: A negative result suggests a very low likelihood of Alzheimer’s pathology, helping clinicians narrow the diagnostic focus elsewhere. []
Performance characteristics: In a clinical study of 312 participants, the Elecsys pTau181 assay demonstrated a negative predictive value (NPV) of 97.9% for excluding Alzheimer’s-associated pathology. In practical terms, this means a negative result offers strong reassurance that Alzheimer’s is unlikely to explain the patient’s symptoms. However, a positive result is not definitive and must prompt further evaluation before concluding a diagnosis. []
That said, experts are urging caution. As preventive neurologist Dr. Richard Isaacson observed, the field is still learning how to interpret these biomarkers, especially in terms of false positives, sensitivity, and longitudinal utility. []
Why this matters
One of the most intriguing promises here is that primary care physicians might integrate a blood-based Alzheimer’s screen into the first evaluation.
The rationale is that if you can confidently exclude Alzheimer’s in many patients, you spare them expensive, invasive, or burdensome testing, while referring those with suggestive results more aggressively.
According to Roche, there are about 4,500 Roche analyzers already installed across US clinical labs—so the infrastructure is at least partially in place for rollout. []
Additionally, neurologists caution that no single biomarker is yet “the answer.” Many clinicians foresee that a panel approach—combining pTau181 with amyloid markers, neurofilament light chain, imaging, and cognitive testing—will offer the best sensitivity and staging insights. []
Also, the temporal sequence is still being probed: amyloid accumulation likely precedes tau pathology, so one marker may “light up” earlier than another. []
Related: A new clue in Alzheimer’s could rewrite what we know about the disease