New Blood Test Brings Hope for Alzheimer’s Detection
A cutting-edge blood test known as p-tau217 is making waves as a potential marker for Alzheimer’s disease. Researchers at the University of Gothenburg, in collaboration with colleagues at the University of Lund and in Montreal, Canada, have unveiled an innovative method that combines this test with a two-step process, showing incredible accuracy in identifying or ruling out a critical early sign of Alzheimer’s.
Over the years, scientists have been working hard to find markers in blood that could help spot Alzheimer’s disease (AD) earlier. The tau protein, particularly its phosphorylated form (p-tau), which plays a significant role in AD development, has been a key focus of research and advancements.
The latest blood-based p-tau biomarkers, including one called p-tau217, have shown immense potential as practical tools for screening individuals experiencing memory issues or early cognitive symptoms linked to Alzheimer’s.
However, despite the promise, a lingering concern has been the risk of misdiagnosis, leading to both false positives (mistakenly identifying someone with AD) and false negatives (failing to identify someone with AD). These errors could have ethical, psychological, and financial implications, as well as potential risks tied to unnecessary treatments.
To address these concerns, the researchers from the University of Gothenburg devised a new approach to integrating blood biomarkers into clinical practice.
The Two-Step Solution
Their innovative strategy involves a two-step process. In the first step, a diagnostic model combines plasma p-tau217 with age and APOE e4 status to assess the risk of amyloid PET positivity in patients with mild cognitive impairment (MCI). In the second step, confirmatory testing using CSF Ab42/40 ratio (or amyloid PET) is carried out for those with uncertain outcomes from the first step.
The study included 348 participants with MCI from the Swedish BioFINDER studies, and the results were validated in the TRIAD cohort from McGill University in Canada. This validation was done using an independent method to analyze plasma p-tau217.
The researchers evaluated different threshold strategies to categorize participants into low, intermediate, and high-risk groups for “Aβ positivity” (indicating AD-type pathology). At stringent thresholds with 97.5% sensitivity, the model had only 6.6% false negatives. At the same time, the stringent 97.5% specificity resulted in only 2.3% false positives.
For the participants falling into the intermediate risk group, further evaluations using CSF Aβ42/40 showed strong agreement (86%) with amyloid PET results. These findings were confirmed in the independent McGill cohort.
A Promising Future
This study introduces a two-step model that relies on a blood plasma p-tau217 test to assess the risk of brain amyloidosis and early AD pathology in individuals with MCI. The exceptional accuracy of the blood test in step one could lead to timely diagnosis and treatment initiation for high-risk patients, while also providing certainty in excluding AD for those at low risk. Moreover, the reduced need for costly confirmatory testing in the intermediate risk group could lead to significant cost savings.
In the quest to better understand and combat Alzheimer’s, this innovative approach brings us closer to early detection and intervention, offering a ray of hope for those affected by this complex disease.