A barely bruised brain can send out molecular SOS signals in the blood for days after an injury, researchers report this week in JAMA Neurology.
The finding suggests that new blood tests, already in development to detect those signals, may be able to identify even the mildest concussion, well after a blow to the head.
“It is common in patients with concussion or mild concussion [traumatic brain injury] not to seek immediate medical attention,” the authors write. Children, in particular, can have delayed or mild symptoms and go right away without treatment. Leaving a concussion undiagnosed can mean returning to work or school too quickly, thwarting the brain’s attempts to heal. This can lead to dizziness, memory loss, depression and headaches. And if a patient returns to play or sports too quickly, further blows to the head can lead to more serious or even permanent injury.
“This test could take the guesswork out of making a diagnosis by allowing doctors to easily look for a specific biomarker in the blood,” said lead researcher Linda Papa, an emergency medicine physician and researcher at Orlando Health, in a statement. press release.
Scientists already knew that certain molecules show up in the blood after brain injury, including glial fibrillary acidic protein (GFAP). This protein is normally found in glial cells, which are supporting cells in the brain that surround nerve cells. After an injury, GFAP bursts out of the glial cells and – most importantly – readily crosses the blood-brain barrier.
While scientists are working on commercial tests for GFAP, it wasn’t clear how long this protein stays in the blood. To find out, Papa and her colleagues tracked GFAP in the blood of 584 adult volunteers who came to the emergency room within four hours of a head injury. Based on CT scans, 325 of those patients had mild to moderate concussions. Volunteers whose CT scans revealed no concussion acted as controls in the study.
The volunteers’ GFAP levels were monitored at regular intervals while they were in the hospital. The longest stay was seven days. Patients who had been hit but did not develop a concussion had almost zero GFAP in their blood throughout the duration of the study. For volunteers with mild to moderate concussions, the researchers found that GFAP lingered at a high level for the first 60 hours before tapering off. But even seven days after the injury, researchers were still able to detect slightly elevated levels of GFAP.
JAMA Neurology2015. DOI: 10.1001/jamaneurol.2016.0039 (About DOIs).