Scientists at Washington University School of Medicine in St Louis in the US have discovered a diagnostic marker that can identify individuals with a primary tauopathy known as corticobasal degeneration (CBD).

The biomarker, which can identify people with this condition with an accuracy of up to 89%, could be developed into a tool for screening potential volunteers for research studies and clinical trials that are specific to CBD.

It can also help find individuals who may benefit from CBD-specific treatments.

Washington University School of Medicine in St. Louis neurology assistant professor Chihiro Sato said: “A patient comes in with stiffness, balance problems, slurred speech and memory issues, and it could be CBD, but it also could be progressive supranuclear palsy (PSP) or Alzheimer’s or other diseases.

“This biomarker can reliably identify people with CBD, which means we can use it to enrol people in clinical trials.”

As part of the study, which is published in Nature Medicine, Sato and Kanta Horie, another neurology associate professor at the university, and colleagues used a highly sensitive technique developed in 2020 to look for different forms of tau that are linked to primary tauopathies.

The research team investigated cerebrospinal fluid and brain tissues obtained from people who had died of movement disorders and dementia.

Specific diseases of these people were also confirmed at autopsy.

For comparison, the researchers also examined samples from people without dementia.

Two particular forms of tau were found to be unusually high in the brains and low in the cerebrospinal fluid of patients with CBD and a subset of FTLD-MAPT.

The tau forms were microtubule-binding region (MTBR)-tau 275 and MTBR-tau 282.

In further investigation, it was observed that these two forms differentiate people with CBD from those with other primary tauopathies with an accuracy of 84% to 89%, depending on the disease.

The new biomarker is also expected to expedite efforts for the development of CBD treatments.