The test has a “higher accuracy” in screening Alzheimer’s.
A recent study suggests that screening for Alzheimer’s disease could be revolutionized by testing an individual’s blood for a protein called phosphorylated tau (p-tau). This method could offer high accuracy even before observable symptoms appear. The research specifically examined the detection of p-tau217, a key biomarker of Alzheimer’s that increases alongside the accumulation of damaging proteins, beta-amyloid and tau, in the brains of those with the disease. The current diagnostic methods, involving brain scans or spinal taps, are often inaccessible and costly. In contrast, the blood test, known as the ALZpath pTau217 assay, demonstrated accuracy rates of up to 96% for elevated beta-amyloid levels and up to 97% for identifying tau.
Lead author Nicholas Ashton, a professor of neurochemistry at the University of Gothenburg in Sweden, emphasized the test’s impressive accuracy, comparable to advanced techniques like cerebrospinal fluid tests and brain scans. The study encompassed 786 participants, averaging 66 years old, who underwent brain scans, spinal taps, and blood sample collection. The results indicate the blood test’s potential as a robust screening tool, with expectations for imminent clinical use.
While the ALZpath pTau217 assay is currently limited to research purposes, it is anticipated to become clinically available soon, with an estimated cost ranging from $200 to $500. The authors underscored the blood test’s potential to enhance early and precise Alzheimer’s diagnosis, leading to improved patient management and timely access to disease-modifying therapies.
The test’s notable accuracy in identifying tau pathology within individuals testing positive for beta-amyloid suggests its practical use in guiding treatment decisions. For instance, it could help determine the effectiveness of therapies targeting beta-amyloid, such as Leqembi and Aduhelm, particularly in cases with advanced tau pathology.
Despite the blood test’s ability to reduce the need for costly and high-demand examinations, the study acknowledges that not all individuals with identified Alzheimer’s characteristics will necessarily develop the condition. Moreover, the specificity of the p-tau test for Alzheimer’s means a negative result does not exclude other potential causes of cognitive impairment.
In summary, the study positions the blood test as a powerful diagnostic tool for Alzheimer’s disease, offering a potential shift toward routine screening similar to cholesterol tests for heart health. The ability to detect Alzheimer’s-related changes in the brain before symptoms manifest holds promise for early intervention and monitoring treatment effectiveness over time.
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