Football is a game of hard hits, including blows to the head. For decades, players were encouraged to use their helmeted heads to plow down opposing team members. Even with a helmet, though, a major blow to the head can shake the brain inside the skull. This can cause a concussion, or bruise on the brain.
Ever since it was discovered that repeated concussions can cause a long-term brain injury called chronic traumatic encephalopathy (CTE), teams and coaches have been trying to limit play-related concussions. Now, a new study suggests that players may suffer a form of traumatic brain injury simply from taking repeated hits. The hits may not need to be serious enough to cause concussions to be dangerous.
Not CTE, but still worrying changes in the midbrain
The study, which was published in the journal Science Advances, involved testing the brains of 38 college football players from the University of Rochester. During the single season studied, the players received a total of 19,128 blows to the head during play, practices, scrimmages and other encounters. These ranged from "small dings to hard slams," but only two were serious enough to cause concussions.
Nevertheless, the players showed signs of harm. By the end of the season, over two-thirds of the players were found to have a measurable decrease in the structural integrity in the white matter tissue in the players' midbrains. The midbrain is known to be responsible for motor control of the eyes and ears.
Furthermore, the players who sustained the largest number of hits also suffered the greatest damage to the midbrain. Also, rotational hits, where the head is twisted to the side, front or back, damaged the midbrain more than linear (head-on) hits.
The midbrain also acts like a "canary in the coal mine" when it comes to brain injuries, according to one researcher with Carnegie Mellon University and the University of Rochester's Program for Translational Brain Mapping. In other words, if the midbrain has been damaged, it's likely that other sections of the brain have also been affected.
It's interesting to note that brain scans of athletes who had been diagnosed with concussions showed the same issue -- a slight disintegration of the white matter in the midbrain -- as those who received repeated blows to the head but were not diagnosed with concussions.
It's unclear whether the damage is permanent
One weakness in the study is that the researchers didn't have a chance to re-scan the players' brains after the post-season or to make an assessment of the players' motor skills and thinking. Therefore, no information is available about how seriously these brain changes might affect the athlete's daily life.
Moreover, previous research on veteran athletes involved pre-season scans that did not show ongoing white matter disintegration. That may imply that this type of damage heals over time.
However, the damage could also be cumulative, like concussions appear to be.
"Public perception is that the big hits are the only ones that matter," says the Carnegie Mellon/University of Rochester researcher. "The big hits are definitely bad, but the public is likely missing what's causing the long-term damage in players' brains. It's not just the concussions. It's everyday hits, too.