Findings published in the Journal of Neurotrauma claim a new blood test can not only quickly identify traumatic brain injury, but also accurately determine the severity of the injury. If validated, these findings could improve emergency room concussion identification methods and help pinpoint patients who may benefit from extra therapy or experimental treatments.
“Compared to other proteins that have been measured in traumatic brain injury, BDNF does a much better job of predicting outcomes,” says Frederick Korley, M.D., Ph.D., an assistant professor of emergency medicine at the Johns Hopkins University School of Medicine and first author of the new paper.
Traumatic brain injuries affect millions of Americans every year and range from so-called “mild” TBI – commonly called concussions – to much more severe injuries. While mild TBI is linked to relatively limited symptoms such as headache, nausea, or blurred vision, more severe forms of TBI are associated with dangerous symptoms like seizures, memory and attention problems, muscle weakness, and even coma or death.
These symptoms are most often caused by damaged brain cells, but most physicians currently rely on CT scans and patient symptoms to determine the severity of brain injury. While CT scans can detect bleeding in the brain, they are incapable of picking up damage to brain cells.
“A typical situation is that someone comes to the emergency department with a suspected TBI, we get a CT scan, and if the scan shows no bleeding, we send the patient home,” says Korley. “However, these patients go home and continue having headaches, difficulty concentrating and memory problems, and they can’t figure out why they are having these symptoms after doctors told them everything was fine.”
In their effort to improve diagnostic methods for concussion, Korley and collaborators measured the levels of three specific proteins they believed were involved in brain cell activity in more than 300 patients with TBI and 150 patients without brain injuries. The team then followed the participants with TBI over the following six months.
The team found one protein in particular, called brain-derived neurotrophic factor (BDNF), could predict the severity of a TBI and long-term outcome if measured within 24 hours of a head injury. In healthy individuals, BDNF levels averaged around 60 nanograms per milliliter in the bloodstream. In comparison, individuals with brain injury were less than one-third that amount, averaging less than 20 nanograms per milliliter, with even lower numbers found in individuals with the most severe TBIs.
The results also showed those with the highest levels of BDNF in their bloodstream had largely recovered from their injuries six months later, but those with the lowest levels of BDNF still experienced significant symptoms.
“The advantage of being able to predict prognosis early on is that you can advise patients on what to do, recommend whether they need to take time off work or school and decide whether they need to follow up with a rehab doctor or neurologist,” Korley says. In addition, it could help decide which patients to enroll in clinical trials for new drugs or therapies targeting severe TBIs.
Korley believes the findings call for more research on the link between brain injury severity and BDNF in the blood, as well as whether items known to increase BDNF levels – including exercise and omega-3 fatty acids – may help treat TBI. He said he also would like to know if changes in BDNF levels over time can be a proxy for recovery and used to assess the effectiveness of medical intervention.
“We looked at that very first blood sample obtained within 24 hours of an injury,” he says. “But for BDNF to be used as a surrogate outcome, we’ll have to see what happens to BDNF blood levels down the line, at one, three or six months after the injury.” He and his collaborators have already started collecting data for those prospective studies, he adds.