Blood Test May Detect Concussions Days Later

Following a concussion, it can take days for symptoms to arise that would lead a patient to seek help; by then, the underlying lesions of the impact may have healed enough to make it difficult to confirm the concussion with a brain scan.

A study published March 28 in JAMA Neurology suggests a blood test may be able to detect evidence of a concussion up to one week after the injury occurred.

“Not only could this simple test greatly expand the window for diagnosing concussions, it could make CT scans unnecessary for many people, which reduces their exposure to radiation,” said Linda Papa, M.D., a physician at the Department of Emergency Medicine at the Orlando Regional Medical Center and lead author of the study. Pediatric patients could especially benefit, she told Psychiatric News, as they are particularly vulnerable to radiation damage. Papa added that minimizing computed tomography (CT) scans would save time and money and keep these machines available for people who really need them.

Previous studies by Papa and her team found that changes in two proteins—glial fibrillary acidic protein (GFAP) and ubiquitin C-terminal hydrolase L1 (UCH-L1)—following head trauma injury can help to differentiate the patients in need of a neurosurgical intervention from others. (Both of these proteins are known to become elevated in the brain after a head injury, and both can also pass the blood-brain barrier.) In the current study, her group set out to better quantify the presence of these proteins over time, while also testing whether their diagnostic value could extend to predicting the presence of a concussion.

They took periodic blood samples from 584 adult patients who had been admitted to the Orlando Health trauma center from 2010 to 2014 (325 of whom were diagnosed with a mild to moderate traumatic brain injury) over a week-long period (the first samples were taken within four hours of the injury). Almost all the patients with mild to moderate TBI had a CT scan to confirm the concussion.

They found that both proteins became elevated in the blood within the first hour, though their time courses differed after that; UCH-L1 peaked at eight hours after injury and then declined rapidly over 48 hours, while GFAP levels peaked at 20 hours post-injury and then declined steadily over 72 hours.

“And we generally saw that the more severe the injury, the higher the levels of these markers, which makes them very objective measures of trauma severity,” Papa said.

In terms of predictive value, GFAP proved better at identifying mild to moderate TBI, with accuracy values ranging from 80 to 97 percent over the seven-day screening period (the test was most accurate 36 to 60 hours after injury). UCH-L1 was not as accurate, ranging from 31 percent to 77 percent over the seven-day period (the test was most accurate in the first eight hours).

These protein signatures may also offer clues about long-term outcomes. “After we diagnose concussion patients and send them home, about 70 percent or so will be fine in the long term, but the rest will have recurring problems like headaches and irritability,” she said. “It would be great if we could anticipate potential problems and those patients could come back more regularly, but at this point, however, we can’t tell which patients are which.”

Her team is continuing to monitor the outcomes of the study patients to see how they recover and if their previous GFAP and/or UCH-L1 readings correlate with how they feel six months after the injury.

This study was funded by a grant from the National Institute of Neurological Disorders and Stroke. ■