Lund University Researchers Develop Dual-Marker Blood Test to Drastically Reduce False Positives in Early Alzheimer's Diagnosis

Lund University researchers combine two tau markers to improve Alzheimer's diagnostic accuracy to 80%, reducing false positives in early screening.

By: AXL Media

Published: Mar 24, 2026, 5:17 AM EDT

Source: Information for this report was sourced from Lund University

Addressing the Precision Gap in Early Detection

Alzheimer's disease is characterized by the decades-long accumulation of amyloid-beta and tau proteins, often appearing in the bloodstream up to 20 years before physical symptoms manifest. While modern blood tests are highly effective at detecting early signs of these proteins, they often struggle with clinical specificity. Currently, over 30% of the elderly population shows some biological markers of Alzheimer's without having developed the actual disease. Researchers at Lund University, led by Dr. Niklas Mattsson-Carlgren, identified a critical need for a diagnostic tool that could determine if these measurable changes are the true cause of a patient's cognitive impairment or merely early-stage biological shifts.

The Limitations of Single-Marker Testing

The study analyzed 572 individuals from the BioFinder2 project who sought medical care for cognitive difficulties. Initial tests focused on p-tau217, a protein that undergoes chemical changes as Alzheimer's progresses. While 97% of patients with high p-tau217 levels also had amyloid in the brain, only 199 out of 350 actually met the clinical criteria for established Alzheimer's disease. This resulted in a 43% false-positive rate for those with high protein levels who did not yet exhibit the full disease state. According to Dr. Mattsson-Carlgren, a single blood marker can often produce a positive result in people who do not yet meet the diagnostic thresholds for the condition.

Introducing a Secondary Marker for Clinical Accuracy

To clear the diagnostic picture, the research team introduced a second tau marker known as eMTBR-tau243. This specific marker is linked to a later, more advanced stage of the disease, making it a more useful indicator of clinical progression. When the two markers were analyzed in tandem, the results were far more precise: 55% of the patients who initially tested positive for p-tau217 also showed elevated levels of eMTBR-tau243. This combination allowed the researchers to identify patients with established Alzheimer's with an 80% accuracy rate, effectively filtering out those whose symptoms might be caused by other conditions.