Study: Sub-concussive Hits Cause Serious Damage To Brain

A new study conducted by researchers from Carnegie Mellon University in Pennsylvania and the University of Rochester in New York shows that concussions aren’t the sole cause of damage to the brain in contact sports like football. The new research indicates typical hits sustained from playing just one season of college football can harm a player’s brain, even if they are not diagnosed with a concussion. The team says its findings show that all blows to the head need to be closely monitored by doctors and coaching staff.

Injuries that fall short of concussions, known as sub-concussions, are often overlooked by clinicians because they don’t present any signs or symptoms like concussions do. However, previous research has shown that repeated hits to the head could be just as damaging to the brain as concussions. A January 2018 study from Boston University found head impacts may be behind chronic traumatic encephalopathy (CTE), even if they do not reach the level of a concussion.

In the new study, the researchers recruited 38 University of Rochester football players to wear helmets outfitted with accelerometers to track the number and force of hits during practices and games. The researchers also measured the direction, location and magnitude of the helmet hits. Each player in the study received an MRI scan within two weeks of the start of each season and within one week at the end. All contact that produced forces of 10 gs or greater were logged during the experiment.

Nearly 20,000 hits were logged for the players across all practices and games. Of those hits, the median force was around 25 gs. The researchers looked specifically at the midbrain, located in the center of the head and just beneath the cerebral cortex. The midbrain supports functions like eye movements, hearing, and temperature regulation. The researchers hypothesized that this structure would be a good indicator of the impact of sub-concussive hits.

Results showed that even though only two of the 38 players received a concussion, more than two-thirds of them showed that the structural integrity of the white matter of their midbrains was greatly reduced after the season was over. The amount of the white matter reduction was associated with the number of impacts that caused the brain to rotate inside the skull. First author Dr. Adnan Hirad, an MD candidate at the School of Medicine and Dentistry at the University of Rochester, said, “Just because you don’t develop a concussion doesn’t mean you don’t have changes and damage to the brain. It doesn’t mean you’re not sustaining an injury.”