In a significant development, Dr. Suzanne Schindler of the Washington University School of Medicine conducted a new study that reveals variable levels of accuracy among commercial blood tests used to diagnose Alzheimer's disease, marking a significant advancement in Alzheimer's research. Dr. Suzanne Schindler presented the findings at the Alzheimer's Association International Conference in Philadelphia on July 30.

Dr. Schindler and her team conducted tests on six commercially available blood tests, four of which are currently in clinical use, to assess their effectiveness in identifying Alzheimer's disease. As part of a project by the Foundation for the National Institutes of Health Biomarkers Consortium, the study looked at these tests to see how well they could find changes in the brain related to Alzheimer's, specifically amyloid plaques.

"Some blood tests are accurate, while others are not, and doctors don't know which tests to use," said Dr. Schindler, an associate professor of neurology at Washington University and the study's lead author. "With this head-to-head comparison, doctors now have more reliable information about which tests will best help them provide an accurate diagnosis to their patients."

The study's findings highlight the importance of appropriately diagnosing Alzheimer's disease early on, especially given the availability of new medicines that may alter the course of the illness. The Food and Drug Administration (FDA) has approved two medications that target amyloid, although both therapies are only appropriate for people who have moderate symptoms.

The study aimed to identify important Alzheimer's indicators in blood samples, such as amyloid plaques and tau tangles, as well as diminished brain sizes. The study evaluated six tests, developed by ALZpath, C2N Diagnostics, Fujirebio Diagnostics, Janssen, Quanterix, and Roche Diagnostics, and deemed C2N Diagnostics and Fujirebio's tests the best. C2N Diagnostics' PrecivityAD2 and Fujirebio's Lumipulse stood out for their precision.

The study discovered that detecting a biomarker called phosphorylated tau 217 (p-tau 217) was especially effective. "P-tau217 alone can do it all," said Kellen Petersen, PhD, a neurology instructor at the School of Medicine who co-led the data analysis. "It correctly predicted amyloid and tau levels in the brain, brain sizes, and cognitive deficits. It was more accurate than any other biomarker or combination altogether."

The findings are consistent with a June study by the Global CEO Initiative on Alzheimer's Disease, which advised that blood tests for Alzheimer's satisfy performance levels comparable to FDA-approved cerebrospinal fluid tests, which are approximately 90% accurate. Dr. Schindler, the paper's primary author, validated that tests measuring p-tau217 satisfied this precision criterion, unlike others.

The study's data, as well as the methods utilized, are available for future research through the Alzheimer's Disease Neuroimaging Initiative (ADNI).