Blood-Based Biomarker Testing Improves Neurologists' Diagnostic Concordance for Early Alzheimer's
KEY TAKEAWAYS
- Access to a high-performance p-tau217/Aβ1-42 blood test improved neurologists’ diagnostic concordance for mild/early Alzheimer disease in simulated patient encounters.
- The test was associated with reduced PET/CSF ordering, suggesting blood-based biomarkers may help streamline diagnostic workups when used appropriately.
- Findings are promising but limited to virtual cases; prospective real-world studies are needed to determine effects on diagnosis, treatment decisions, and patient outcomes.
Results from a randomized virtual trial presented at the 2026 Alzheimer's Association International Conference (AAIC) suggest that access to a high-performance blood-based p-tau217/Aβ1-42 test significantly improved neurologists' diagnostic concordance for early Alzheimer disease while reducing reliance on confirmatory positron emission tomography (PET) imaging and cerebrospinal fluid (CSF) testing. The findings support the growing role of blood-based biomarkers in the diagnostic workup of suspected Alzheimer disease, particularly as disease-modifying therapies become more widely available.
The prospective study enrolled 142 US board-certified neurologists who completed 852 interactive virtual patient encounters across 2 rounds. Participants were randomized to receive results from a high-performance p-tau217/Aβ1-42 blood biomarker test at the start of the second-round case workup or to standard evaluation without access to the p-tau217/Aβ1-42 ratio test, although control participants could order other commercially available blood-based biomarkers. The simulated cases represented patients with mild/early Alzheimer disease, intermediate/moderate Alzheimer disease, vascular dementia, and hepatic encephalopathy.
The largest statistically significant benefit was observed in mild/early Alzheimer disease, the population most likely to be considered for disease-modifying therapy. Access to the blood biomarker improved diagnostic concordance with expert-defined case diagnoses by 26.2 percentage points compared with controls (P=.007). Investigators also observed a directional reduction in PET/CSF ordering across the intervention arm. Among encounters in which neurologists did not order additional blood-based biomarkers, diagnostic concordance improved by 35.0 percentage points (P=.049), while PET/CSF ordering declined by 23.9 percentage points (P=.046).
What does this mean for practice?
As blood-based biomarkers become integrated into Alzheimer disease diagnostic workflows, neurologists want to know whether they meaningfully influence clinical decision-making. This study suggests that access to a high-performing blood biomarker test may improve diagnostic concordance for patients with suspected early Alzheimer disease while reducing reliance on more invasive and less accessible confirmatory testing. However, the findings reflect physician decision-making in simulated patient encounters rather than patient outcomes in routine clinical practice. Additional prospective studies will be needed to determine whether these improvements translate into more efficient diagnosis, more appropriate use of confirmatory testing, earlier treatment initiation, and ultimately improved patient outcomes.
This study was presented by representatives of Beckman Coulter Diagnostics, Brea, CA.
Source
Das L, Burgon T, Bhatt K, Ferrara KG, Paculdo D, De Belen E, Valdenor C. Impact of a blood-based biomarker on neurologist diagnostic decision-making for Alzheimer's disease: a randomized virtual trial. Presented at: Alzheimer's Association International Conference; July 2026; London, UK.