A new study[1] published in Nature Communications this summer brings new insight into the root causes of chronic traumatic encephalopathy (CTE). Symptoms of CTE include cognitive impairment, behavioral changes, mood disorders, and motor control issues.[2] While commonly associated with pro football players, CTE has also been documented to affect other contact sports athletes, military veterans, and survivors of domestic violence.
Though CTE has a known association with repeated blows to the head, understanding what type of exposures, and how much, have remained unanswered questions. This new study examined football helmet data that measured the type and force of impact and combined it with brain studies from deceased pro football players.
Repeated Blows over a Long Period of Time a Better Predictor than Number of Concussions
The data strongly linked the number of years a person is involved with a contact sport and the cumulative number of hits to the head with an increased risk of CTE. The study authors found that, “each additional year of play was associated with 15% increased odds of being diagnosed with CTE.” Furthermore, “Every additional estimated 1,000 head impacts were associated with 21% increased odds of being diagnosed with CTE.” Stronger linear and rotational impacts were also associated with higher risk of developing CTE.
While concussions are often at the forefront of the discussion around football safety, the number of concussions an athlete was diagnosed with was not predictive of CTE. The study suggests that repeated hits over an extended period, even when those hits are at a “subconcussive” level, are the main driver of CTE symptoms. However, as noted by the study authors, it is difficult to quantify the number of concussions any athlete may have had, as the diagnostic criteria for concussion has changed since the deceased football players involved in the study were actively playing.
What Does this Mean for Student Athletes and CTE?
The more hits an athlete takes, and the more years they experience these hits, the greater their risk of developing CTE. The risk is more pronounced for football positions likely to experience more blunt force. The study analysis estimates that a college athlete playing defensive linebacker will experience roughly 841 hits per season, while a college athlete playing wide receiver will experience roughly 314 hits per season.
The study authors caution that much more data is needed before scientists can fully determine at what threshold a person is likely to develop CTE. It is important that student athletes, coaches, and parents stay informed about the risks associated with repeated blows to athletes’ heads.
[1] https://www.nature.com/articles/s41467-023-39183-0
[2] https://www.mayoclinic.org/diseases-conditions/chronic-traumatic-encephalopathy/symptoms-causes/syc-20370921
