A new study led by researchers at LMU University Hospital and international collaborators has identified a blood biomarker, brain-derived tau (BD-tau), that reflects the extent of brain injury after ischemic stroke. The research shows that BD-tau can predict patient outcomes months to years after a stroke.
Currently, imaging such as CT or MRI scans provides only limited snapshots of brain damage following a stroke. While blood tests are used to monitor acute injuries in other organs like the heart or kidneys, the brain has lacked a similar marker until now.
The study began at LMU University Hospital in 2013 with the aim of developing a reliable blood test for continuous monitoring of brain injury and treatment effects. Researchers measured BD-tau levels repeatedly from hospital admission through day seven in their initial cohort and validated their findings in two additional multicenter cohorts, including data from a phase 3 clinical trial. More than 1,200 stroke patients participated in these analyses.
Findings indicate that early BD-tau levels, measured within hours of symptom onset, were linked to the degree of initial brain damage and predicted final infarct size. Larger increases in BD-tau during the first 24 to 48 hours were associated with infarct growth and complications such as recurrent events. The biomarker was also found to be a strong predictor of recovery, forecasting functional outcomes at 90 days and beyond as well as or better than other biomarkers or imaging-based measures.
In addition, BD-tau revealed treatment effects: its rise was less pronounced when vessels were fully reopened after thrombectomy, and patients who received the neuroprotectant nerinetide had smaller increases compared to those given placebo in a randomized trial.
"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.
Researchers note that further studies are required to define reference ranges and thresholds for BD-tau measurement and to develop faster testing methods suitable for clinical use. In the long term, this blood test may help clinicians monitor disease progression more closely, detect complications earlier, and assess new therapies more efficiently in clinical trials. It may also have potential applications for assessing brain injury in other neurological diseases.
