Scientists are on the verge of pinpointing specific biomarkers in the blood associated with varying degrees of brain injury (TBI) in emergency room patients. By 2021, technological advances could result in a simple blood test capable of detecting gradients of brain injury ranging from a full-blown concussion to subconcussive or non-concussive head trauma.

Source: Orlando Health

This week, Linda Papa and colleagues at Orlando Health reported potentially groundbreaking discoveries from one of the most extensive studies of blood biomarkers associated with brain injury. The cohort for this study included more than 700 children and adults who visited the emergency room within four hours of potential head trauma. The results of this prospective cohort study (Papa et al., 2019) were published on August 25 in the journal BMJ Paediatrics Open.

This blood test measured two proteins (GFAP and UCH-L1) found in the human brain that are released into the bloodstream after an injury. Higher levels of these blood biomarkers appear to indicate a concussion or subconcussive injury. Papa has been investigating the GFAP and UCH-L1 blood biomarkers for over a decade.

Her most recent study (2019) focused on three groups of patients: (1) those with overt symptoms of a concussion, (2) emergency room patients with head trauma but without any apparent signs of concussion; (3) patients with a body injury that did not involve head trauma or a concussion.

Oftentimes, immediately after experiencing head impact exposure (HIE), people with mild traumatic brain injury do not display any concussion symptoms or visible impairments. Additionally, CT scans frequently miss the subtle signs of subconcussive brain injury. Subsequently, those who have suffered head trauma without concussion symptoms are classified as having "no injury."

However, this "clean bill of health" can be misleading; experiencing lots of "no injury" head impact exposures adds up. Most experts agree that repeated head impacts (that are subconcussive or non-concussive) can cause wear and tear on the brain that accumulates over time.

Last year, a study (Stemper et al., 2018) led by Brian Stemper of Marquette University and the Medical College of Wisconsin reported that repeated head impact exposure on the playing field may push an 's brain to a tipping point where he or she is more likely to suffer a concussion. As Stemper and coauthors explained, "This unique analysis provided further evidence for the role of repetitive head impact exposure as a predisposing factor for the onset of concussion."

What makes the new blood test by Linda Papa and associates potentially revolutionary is that it can take the guesswork out of gauging the severity of head impact exposure for athletes and non-athletes.

In previous concussion-related studies, Linda Papa focused on professional and recreational athletes. Papa's current research was expanded to include subconcussive brain injury in a large cohort of children and adults from all walks of life. According to a news release from Orlando Health, "There are very few studies addressing the impact of subconcussive injuries following head trauma in the civilian population, as opposed to military members or athletes."

"It is estimated that up to 3.8 million concussions occur in the U.S. annually from organized and recreational sports—and there are more than 2 million ER visits for and concussions," Papa said in a statement. "It is a significant health problem in both athletes and non-athletes."

Of note, Papa et al. (2019) found elevated levels of the GFAP and UCH-L1 blood biomarkers in patients with non-concussive head trauma; the researchers speculate that these biomarkers are indicative of a subconcussive brain injury. On a quantitative spectrum, it appears that higher levels of these blood biomarkers and the severity of TBI may go hand in hand.

One of the most exciting aspects of pinpointing blood biomarkers associated with gradients of brain injury in concussive, subconcussive, and non-concussive trauma is that someday soon these tests could be administered on the sidelines of professional sporting events or at the site of an accident involving the general population.

A few different companies are currently developing handheld devices capable of administering point-of-care tests that measure blood biomarkers associated with brain injury. Hopefully, in the near future, these devices will be able to detect concussive and subconcussive injuries at the scene of car or bike crashes, in a military setting, recreational sports environments, or anywhere an EMT wants to gauge the severity of head impact exposure. According to Linda Papa, "The technology is only a year or two away."