Blood Test Developed for Early Detection of Alzheimer’s Disease

A new blood test developed by researchers at Washington University School of Medicine in St. Louis and Lund University in Sweden can both detect Alzheimer’s disease and determine how far it has progressed. The study, published in Nature Medicine on March 31, offers a more accessible method for staging the disease than current imaging techniques.

Current limitations of Alzheimer’s diagnostics

Several blood tests already help doctors confirm a diagnosis of Alzheimer’s disease in individuals with cognitive symptoms. However, these tests do not indicate the disease's stage or the severity of cognitive impairment. Staging is vital because current Alzheimer’s therapies are most effective in the early stages of the condition.

Until now, positron emission tomography (PET) scans of the brain have been the gold standard for staging Alzheimer’s disease, identifying the presence and spread of amyloid plaques and tau tangles. However, these scans are costly and not widely available, particularly outside major research centers.

New biomarker reflects disease progression

In this study, researchers measured levels of a protein fragment known as MTBR-tau243 in blood samples. This marker is associated with the formation of tau tangles in the brain, a key feature of Alzheimer’s pathology that correlates with cognitive decline. In previous work, the same team found that MTBR-tau243 levels in cerebrospinal fluid closely reflected the extent of tau aggregation. The current study extended these findings to blood samples.

The researchers used data from two study groups: a cohort of 108 individuals at Washington University’s Charles F. and Joanne Knight Alzheimer Disease Research Center and a subset of 55 individuals from the Swedish BioFINDER-2 cohort. They validated their results in a separate group of 739 individuals from the remaining BioFINDER-2 cohort.

Participants represented a range of disease stages, from presymptomatic individuals with elevated brain amyloid but no cognitive symptoms to individuals with late-stage Alzheimer’s dementia. The study also included cognitively healthy individuals and those with cognitive symptoms caused by conditions other than Alzheimer’s.

MTBR-tau243 distinguishes between disease stages

Analysis showed that MTBR-tau243 levels in blood samples were strongly associated with tau tangles in the brain, with an accuracy of 92%. These levels remained normal in asymptomatic individuals, regardless of amyloid status. Among those with Alzheimer’s-related cognitive impairment, levels increased significantly as the disease advanced. In individuals with dementia, MTBR-tau243 levels were up to 200 times higher than in those with mild cognitive impairment.

“In clinical practice right now, we don’t have easy or accessible measures of Alzheimer’s tangles and dementia, and so a tangle blood test like this can provide a much better indication if the symptoms are due to Alzheimer’s and may also help doctors decide which treatments are best for their patients.”

Dr. Randall J. Bateman.

Crucially, MTBR-tau243 levels were normal in individuals with cognitive symptoms due to other causes, making the test highly specific to Alzheimer’s dementia.

Potential clinical applications

The technology has been licensed by Washington University to C2N Diagnostics, a company that has already developed amyloid blood tests. These existing tests measure another tau protein form, p-tau217. The new MTBR-tau243 test is seen as complementary, offering information about disease stage, while p-tau217 helps confirm diagnosis.

 “When both of these biomarkers are positive, the likelihood that Alzheimer’s is the underlying cause of a person’s cognitive symptoms increases significantly, compared to when only p-tau217 is abnormal. This distinction is crucial for selecting the most appropriate treatment for each patient.”

Dr. Oskar Hansson.

The ability to combine both biomarkers could improve diagnostic accuracy and help clinicians choose the most appropriate therapies. While two FDA-approved therapies currently target amyloid in early stages of the disease, other experimental treatments under investigation target tau or different aspects of Alzheimer’s pathology. As more drugs become available, being able to determine the stage of disease using a blood test may support more personalized treatment strategies.

Reference: Horie K, Salvadó G, Koppisetti RK, et al. Plasma MTBR-tau243 biomarker identifies tau tangle pathology in Alzheimer’s disease. Nat Med. 2025. doi: 10.1038/s41591-025-03617-7

This article has been republished from the following materials. Note: material may have been edited for length and content. For further information, please contact the cited source. Our press release publishing policy can be accessed here.

This content includes text that has been generated with the assistance of AI. Technology Networks' AI policy can be found here.