BD-tau blood test tracks brain injury after stroke over time

Stroke is a medical emergency, yet clinicians still have limited options to monitor how brain damage progresses in the hours and days after symptom onset. In ischemic stroke, part of the brain is no longer adequately supplied with blood. Today, clinical decisions for people with sudden paralysis or speech problems rely largely on CT scan or MRI imaging. However, repeated imaging is logistically demanding, not always feasible, and imaging parameters may reflect later recovery only to a limited extent.

For other organs, blood tests can indicate acute injury, but the brain has lacked a comparable marker. “In stroke care, we currently face the problem that we cannot continuously track how brain injury evolves over time – and this limits our treatment decisions,” says Dr. Steffen Tiedt, scientist at the Institute for Stroke and Dementia Research (ISD) and attending physician in the Stroke Unit at LMU University Hospital’s Department of Neurology.

To address this gap, a study initiated at LMU University Hospital in 2013 aimed to develop a reliable blood test that can reflect brain injury continuously and make treatment effects measurable. The team identified brain-derived tau (BD-tau) as a blood biomarker capturing tau protein originating from the central nervous system.

In the LMU study cohort, BD-tau was measured repeatedly from hospital admission through day 7. The findings were validated in two independent multicenter cohorts, including a biomarker-based analysis within a phase 3 clinical trial. Overall, data from more than 1,200 stroke patients were included. The work was co-first authored by Dr. Naomi Vlegels and Nicoló Luca Knuth and published in Science Translational Medicine.

According to the report, BD-tau blood levels reflected the extent of brain injury:

• Early measurements within hours were associated with initial damage and predicted final infarct size.
• Larger increases in the first 24-48 hours were linked to infarct growth.
• Elevated levels were observed in complications such as recurrent events.

BD-tau also predicted recovery, forecasting functional outcome at 90 days and beyond at least as well as, or better than, other blood biomarkers and even imaging-based infarct volumes.

BD-tau also captured therapy-associated differences. After thrombectomy, BD-tau rose less when the vessel was fully reopened. In a randomized study, the rise in BD-tau was markedly smaller with the neuroprotectant nerinetide than with placebo. “We don’t just need a picture from the beginning of a stroke – we need a way to follow the course of brain injury over time. BD-tau could become a kind of ‘troponin for the brain’ – an objective blood marker that makes progression and treatment effects measurable,” says Tiedt.

Further studies are needed to define reference ranges and thresholds and to enable faster measurement, ideally as a point-of-care test.

MEDICA-tradefair.com; Source: LMU Hospital