A new study led by Niklas Mattsson-Carlgren at Lund University, published on Mar. 23, reports that combining two blood markers can improve the accuracy of Alzheimer's disease screening and reduce false positives.
The findings are significant for people undergoing cognitive assessments, as current blood tests may indicate Alzheimer’s-related changes even when patients do not yet meet the full criteria for the disease. This can lead to uncertainty and potential misdiagnosis.
Researchers measured levels of the protein p-tau217 in 572 individuals who sought medical care due to cognitive impairment. High levels of p-tau217 were found to be a strong indicator of Alzheimer’s-related brain changes; among those with elevated p-tau217, 97 percent also had amyloid in the brain. However, only about half had developed Alzheimer's disease at the time of testing. "A blood marker can sometimes produce a positive result in people who do not yet meet the criteria for the disease; these are known as false-positive results. This was the case for 43 per cent of those with high p-tau217 levels – they exhibited the changes but did not meet all the criteria for the disease," said Mattsson-Carlgren.
To address this issue, researchers analyzed another tau marker called eMTBR-tau243 alongside p-tau217. When both markers were present at elevated levels, they identified established Alzheimer’s cases with around 80 percent accuracy and reduced false positives from 43 percent to 16 percent. The results were validated in a separate group of American participants experiencing similar cognitive issues.
"By combining blood markers, we can better identify which people have Alzheimer's disease and which of them have such an advanced stage of the disease that it leads to symptoms," said Mattsson-Carlgren.
People who tested positive for both biomarkers experienced faster cognitive decline and greater accumulation of tau protein over time. "The new marker still requires analysis using advanced techniques such as mass spectrometry. The next step is to investigate whether the test can be simplified, and whether it can be used more widely, in primary care, for example," said Mattsson-Carlgren.
The study was conducted through collaboration between Lund University and Washington University.
