Blood Test Shows Alzheimer’s Signature: A Step Toward Easier Screening
Ottawa – Detecting Alzheimer’s disease (AD) biomarkers in blood plasma could offer a simpler, less invasive alternative to cerebrospinal fluid (CSF) testing, potentially enabling earlier diagnosis and treatment. However, experts urge caution before widespread adoption in primary care.
From Spinal Fluid to Blood: A Shift in Alzheimer’s Diagnostics
For decades, Alzheimer’s pathology has been confirmed by detecting biomarkers—especially amyloid and tau proteins—in CSF obtained via lumbar puncture. Now, research presented at the Canadian Neurological Sciences Federation Congress 2025 suggests that similar pathological “signatures” are also detectable in blood plasma.
“We’ve always known Alzheimer’s leaves a signature in CSF,” said Dr. Mari DeMarco, clinical chemist at St. Paul’s Hospital and professor at the University of British Columbia. “We now know it leaves a signature in blood too.”
Key Biomarker: Phosphorylated Tau 217
Among the most promising plasma biomarkers is phosphorylated tau 217 (p-tau 217), which shows strong association with AD pathology.
Dr. DeMarco highlighted how advances in mass spectrometry have dramatically improved biomarker assay accuracy—addressing past issues with variability and reliability in CSF-based testing.
“Mass spectrometry is now considered the gold standard,” she noted.
Technical Challenges: Sample Handling Remains Critical
Despite its potential, plasma biomarker testing is not without challenges:
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Sample integrity: Careful collection, handling, and timely processing are essential to ensure reliable results.
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Stability during storage: The long-term stability of plasma biomarkers can affect diagnostic accuracy.
“Getting samples safely to the analyzer for accurate quantification remains a key concern,” DeMarco warned.
Accessibility vs. Caution: Not Ready for Primary Care Yet
A blood-based test could make Alzheimer’s screening more accessible, reducing the need for invasive lumbar punctures. However, Dr. DeMarco cautioned against prematurely rolling out plasma biomarker testing in routine primary care, citing the need for standardized protocols and further validation.
Outlook: A Promising but Cautious Step Forward
While plasma-based biomarker testing marks an exciting development in Alzheimer’s diagnostics, experts agree: Robust clinical validation, careful laboratory handling, and standardized methodologies will be critical before broad clinical implementation.
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