The big hits are not the only ones that matter.
University of Rochester researchers have discovered that traumatic brain injury is not limited to those who sustain concussions, but also extend to individuals who suffer repetitive hits to the head that don’t manifest into a clinical outcome.
The study, part of the recently launched Open Brain Project, shows that these sub-concussive hits in football and other contact sports have been increasingly recognized as a potential threat to long-term brain health and as a possible cause of chronic traumatic encephalopathy, UR says. The research was funded by the Clinical and Translational Science Awards Program, part of the National Center for Advancing Translational Sciences at the National Institutes of Health, as well as other branches of NIH and the National Football League Charities.
“This study is important because we found that no matter where the head gets hit, the force is translated into a single region of the brain known as the midbrain. Midbrain imaging might be a way in the future to diagnose injury from a single concussive head hit, as well as from repetitive sub-concussive head hits,” says Jeffrey Bazarian, professor of emergency medicine, neurology, neurosurgery and public health sciences at UR’s Medical Center and a co-author of the study.
Adnan Hirad, a fourth-year medical student at the university and a study co-author, notes that the midbrain may serve as a “canary in a coal mine” when it comes to identifying damage. Given that the location of a brain injury can vary, it often is tough for doctors trying to diagnose brain injury using imaging techniques.
“From this study we know that the midbrain region, which is linked to brain functions often affected by a concussion, is the place to look to identify the impact of clinically defined concussions with visible symptoms and silent brain injuries that can’t be observed simply by looking at or behaviorally testing a player, on or off the field,” Hirad says.
The research team studied 38 UR football players before and after three consecutive football seasons through MRI scans. Players wore helmets equipped with impact sensors that captured all hits above 10 g force sustained during practices and games. Researchers found a decrease in midbrain white matter after one season when compared with the preseason. While only a couple of players suffered a clinical concussion during the course of the study, more than two-thirds experienced a decrease in the structural integrity of the brain, URMC says. The number of blows to the head sustained and the rotational acceleration or movement of the head from side to side or front to back were linked more consistently to changes in white matter integrity.
These findings mean that noninvasive structural MRI of the midbrain serves as a clear index of both clinically silent white matter injury as well as frank concussion, the study states, demonstrating that the midbrain is one place to find evidence of long-term damage. Also, the midbrain controls various brain functions such as balance and auditory and visual processing. It is also a region where previous research has found the highest strains related to concussive impact.
“The big hits are definitely bad, but the public is likely missing what’s causing the long-term damage in players’ brains,” says Brad Mahon, an associate professor of psychology at Carnegie Mellon University and scientific director of UR’s Program for Translational Brain Mapping. “It’s not just the concussions. It’s everyday hits, too. And the place to look for the effect of such hits, our study suggests, is the midbrain.”
It has been widely reported that the list of college and professional football players suffering from symptoms of chronic traumatic encephalopathy continues to grow. As researchers like those in Rochester continue to find better ways to diagnose the extent of damage and study the brain as a whole, it is evident that there is work to be done.
The Open Brain Project, established with resources from Mahon’s lab and UR’s Department of Neurosurgery, is one way for patients, clinicians, scientists and students to facilitate research into brain injury and its impact on the body. The digital hub expects to apply for 501(c)(3) status next year.
Smriti Jacob is Rochester Beacon managing editor.