Alzheimer’s Disease Blood Test

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GOTHENBERG, Sweden — An international team of scientists has unveiled a game-changing blood test that could make diagnosing Alzheimer’s disease more accurate than ever. Named p-tau217, the test is based on a specific protein linked to Alzheimer’s and has shown significant promise in early trials.

For years, researchers have been keen on identifying “biomarkers” in blood tests that can detect Alzheimer’s disease (AD). A biomarker is a measurable indicator in the body that can signify the presence or risk of a disease. A variant of tau protein, known as p-tau, has been the focus of many such studies because it’s closely involved in Alzheimer’s pathology.

The newly developed blood-based p-tau biomarkers, particularly p-tau217, are hailed as breakthroughs in screening for Alzheimer’s. This is particularly useful for patients exhibiting early symptoms like memory loss or cognitive decline, making it a clinically valuable tool.

One of the significant challenges of using biomarkers for Alzheimer’s diagnosis has been the rate of false positives and false negatives. Such inaccuracies are not just ethically and psychologically troubling but can also lead to unnecessary medical expenses and treatments. To address these concerns, researchers from the University of Gothenburg, Lund University, and McGill University in Montreal created a novel two-step diagnostic strategy.

Alzheimer's disease symptoms
(Image by Irina Strelnikova on Shutterstock)

How Does the Two-Step Model Work?

The first step involves using the p-tau217 blood test along with the patient’s age and another genetic marker known as APOE e4 to categorize patients with mild cognitive impairment (MCI) based on their risk of developing Alzheimer’s. The second step involves additional confirmatory tests only for those whose results were inconclusive in the first step.

In tests involving 348 MCI participants from Swedish BioFINDER studies and an independent group from McGill University, the two-step model showed impressive results. The model could accurately classify patients with a high or low risk of Alzheimer’s with as little as 6.6% false negatives and only 2.3% false positives.

Game-Changer in Alzheimer’s Diagnosis?

According to the research team, this two-step model can bring significant cost savings to healthcare systems. That’s because it substantially reduces the need for more expensive confirmatory tests, like amyloid PET scans, traditionally used in Alzheimer’s diagnosis. Moreover, for the low-risk group, the new blood test can effectively rule out Alzheimer’s with a high degree of certainty.

“This blood test applied in step 1 shows very high accuracy to identify high-risk patients, who depending on the clinical situation can either be given a diagnosis and be initiated on symptomatic treatments, or in the future be referred to the specialist clinic for possible initiation of disease-modifying treatment,” say the researchers.

The researchers’ findings are published in the scientific journal Nature Aging.

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