A new quick blood test may be able to diagnose traumatic brain injury (TBI) and even determine its severity, according to a new study published in the Journal of Neurotrauma. The test could help determine the best type of treatment for each TBI patient.
Millions of Americans develop TBIs each year. These can range from mild concussions, causing only a headache or temporary blurred vision, to much more severe injuries leading to seizures, confusion, memory and attention problems, muscle weakness, or coma for many months. These symptoms, whether mild or more severe, are generally caused by damaged brain cells.
Until now, most doctors have relied on CT scans and patients’ symptoms to determine whether to send them home and have them resume their usual activities or take extra precautions. However, CT scans can only detect bleeding in the brain, not damage to brain cells, which can occur without bleeding.
“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,” said first author Frederick Korley, M.D., Ph.D., an assistant professor of emergency medicine at the Johns Hopkins University School of Medicine.
“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.”
The researchers wanted to know if a blood test could better predict which patients would have ongoing brain injury-related problems. So they measured the levels of three proteins that they suspected play a role in brain cell activity in more than 300 patients with a TBI and 150 patients without brain injuries. Then, they followed those with a TBI for the next six months.
The found that levels of one particular protein, called brain-derived neurotrophic factor (BDNF), taken within 24 hours of someone’s head injury, could predict the severity of a TBI and how a patient would fare.
While healthy people averaged 60 nanograms per milliliter (ml) of BDNF in their blood, patients with brain injuries had less than one-third of that amount, averaging less than 20 nanograms per ml. Those with the most severe TBIs had even lower levels, around 4 nanograms per ml.
Furthermore, patients with high levels of BDNF had mostly recovered from their injuries six months later. But in patients with the lowest levels of BDNF, symptoms still lingered at follow-up. The findings strongly suggest that a test for BDNF levels, administered in the emergency room, could help stratify patients.
“Compared to other proteins that have been measured in traumatic brain injury, BDNF does a much better job of predicting outcomes,” said Korley.
“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 said.
In addition, it could help decide which patients to enroll in clinical trials for new drugs or therapies targeting severe TBIs.
More research is needed to determine why, at a molecular level, brain injuries decrease levels of BDNF in the blood and whether things known to increase BDNF levels — including exercise and omega-3 fatty acids— could help treat TBIs. Korley also wants to know whether changes in BDNF levels over time can be a proxy for recovery and if they could be used to gauge the effectiveness of a particular treatment.
“We looked at that very first blood sample obtained within 24 hours of an injury,” he said. “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.”
Source: Johns Hopkins Medicine