A Novel Biomarker Enhances Distinction Between Alzheimer’s and Primary Tauopathy

A new biomarker makes it easier to distinguish between Alzheimer’s and primary tauopathy.

Patients frequently arrive at university hospitals with rare and specific disorders that many private practice doctors may not be familiar with, such as primary 4-repeat tauopathies. These conditions primarily affect movement but can exhibit symptoms similar to those of Alzheimer’s disease, making accurate diagnosis a challenge. Researchers from LMU University Hospital have discovered new biomarkers that allow doctors to reliably differentiate between these two diseases, albeit using data from a specific imaging method known as positron emission tomography (PET).

Professor Matthias Brendel, the lead researcher and acting director of the Department of Nuclear Medicine, explains, “The new diagnostic algorithm we created enables healthcare providers to more accurately tell apart Alzheimer’s disease from primary tauopathies, which helps in achieving earlier and more accurate diagnoses and supports tailored treatment plans.” The findings have been published in the journal of the Alzheimer’s Association called Alzheimer’s and Dementia.

In both Alzheimer’s disease and primary 4-repeat tauopathies, large accumulations of tau protein are present in the brain. For many years, tau proteins related to Alzheimer’s disease have been detectable through analysis of the patient’s cerebrospinal fluid (CSF).

Recently, scientists have developed radioactive substances (tracers) that gather at tau aggregates after being injected into the body, making them visible on PET scans. “Our recent study demonstrates that tau can be detected with the new tau PET tracer even in cases of 4-repeat tauopathies. This detection occurs not in the cerebrospinal fluid but rather in very specific regions of the brain known as subcortical areas,” says Roxane Dilcher, the study’s lead author.

However, the PET signal represents just one part of a complicated new diagnostic approach. The researchers have also discovered new biomarkers that indicate the presence of 4-repeat tauopathy. “Diagnosis becomes highly effective when we analyze a combination of cerebrospinal fluid tests, innovative biomarkers, and PET signals from the subcortical regions,” Matthias Brendel adds. “This combination allows us to identify a 4-repeat tauopathy with a high level of confidence.”

Currently, primary 4-repeat tauopathies are mostly diagnosed using clinical criteria without specific biomarkers for definitive diagnosis in patients, notes co-senior author Dr. Nicolai Franzmeier, also part of SyNergy. “The development of a biological definition and associated biomarker workflows will significantly advance the research in this area.”