JACKSONVILLE, Fla. – The thought has always been the more concussions an athlete suffered, the more likely they would be diagnosed with Chronic Traumatic Encephalopathy, better known as CTE. Now, a new study published this year — the largest study of CTE to date — has found a more accurate predictor.
Athletics are entwined in society. Millions of people watch and attend sporting events each year. It is a multibillion dollar industry. There is an understanding that any sport has a level of risk, especially contact sports like football. Over the past few decades, scientists and doctors have researched the risks associated with sports and the impact sports have on the lives of athletes who are well past their final game.
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According to the Mayo Clinic, “Chronic traumatic encephalopathy (CTE) is a brain disorder likely caused by repeated head injuries. It causes the death of nerve cells in the brain, known as degeneration. CTE gets worse over time. The only way to definitively diagnosis CTE is after death during an autopsy of the brain.”
Chris Nowinski, co-founder and CEO of The Concussion Legacy Foundation and the Unite Brain Bank Boston University CTE Center, says there is no cure for CTE. Most people can live until they’re old and have successful lives, but have some quality-of-life implications at the end of their life. Others will have a shorter life because of their own implications linked to CTE.
“We went from a world where I as an athlete and most everyone else were pretty reckless with how we treated our brain in sports, to one where we now are starting to take care of it,” Nowinski said.
It is no secret that contact sports like football are not the safest. Collisions at full speed and being shoved to the ground is not for the weak. The resounding thought was that the more concussions an athlete had from being tackled aggressively correlated to the higher likelihood an athlete would be diagnosed with CTE.
In fact, the largest study to date of CTE, which was published in the scientific journal, Nature Communications, found cumulative force to the head — not diagnosed concussions — is the best predictor of future brain disease like CTE. The study continues to state that focusing on concussions misses the point of how harmful an accumulation of subconcussive impacts can be to an athlete.
Dr. Dan Daneshvar, assistant professor at Harvard Medical School and Chief of Brain Injury Rehabilitation at Mass General Brigham was the lead author of the study. He said the study shows “beyond any doubt” the number of hits to the head is a better indicator of CTE than the number of concussions.
“We had information on is that it is not just one or two bad hits or just one or two concussions that can cause CTE,” Dr. Daneshvar said. “What appears now to be the case is that it’s the total force to the head that increases someone’s risk of CTE.”
The study used data from football helmet sensors that compiled millions of hits over a 20-year span to estimate the cumulative impact of hits on 631 former football players who donated their brains to Boston University for research. Researchers studied:
- How many head impacts each player sustained based on when they played
- The position they played
- How many head impacts each player had
- How hard the head impacts would be at each stage of the player’s career
The findings from researching the helmet sensors and each athlete’s brain showed disparities between each position. For example, linemen sustain less forceful hits compared to other positions, but linemen experience the most G-force of impact each season due to the volume of hits. This is why linemen are more likely to develop CTE than other players.
“You know when we’re talking about concussions those are symptomatic hits to the head,” Dr. Daneshvar said. “That’s a hit in the head that results in symptoms like dizziness or changes in vision or in some cases getting knocked out, loss of consciousness. But what we know from the helmet sensory data now is that for each hit to the head that results in symptoms that result in a concussion, for an average football player they might get around 341 hits to the head that are of equal or greater force than the hit that gave them the concussion.”
The findings clearly showed a relationship between getting hit in the head hard and developing CTE, but did not find a relationship between the number of concussions either diagnosed or a player thought he had and risk of developing CTE.
“The average helmet might attenuate the forces associated with a head impact by 5 or 10% compared to a bad helmet and that’s theoretical,” Dr. Daneshvar said. “The best way to eliminate the total force to the head that an athlete experiences is by eliminating the hits all together.”
Another study conducted by Boston University CTE Center further demonstrates repeated head hits are more harmful for an athlete. The study examined 152 brains that were donated to the center for research. The findings diagnosed CTE in more than 40% of youth, high school and college athletes who died before the age of 30. The athletes — who were mostly football players — were exposed to repetitive head impacts from contact sports.
“As a football player for every one concussion I had, I took 300 hits that were harder than that concussion, but they didn’t cause acute symptoms enough for me to come to the sideline and say ‘I’m messed up’ or for me to be knocked out on the field. But we now know those hits cause brain damage, it’s just microscopic and you have billions of neurons. If you kill a few you’re not going to feel it,” Nowinski said.
Nowinski was a WWE wrestler, but his career ended because of a concussion. He started CTE research in 2006. Throughout his tenure, Nowinski created the first CTE Prevention Protocol which reduces tackles and hits in practice.
“We created the world’s first CTE Prevention Protocol using this data that we think should exist next to every football team’s concussion protocol,” Nowinski said. “Basically the idea is that if you knocked out half of the hits in practice for linemen in football over a high school and college career, you would reduce their risk of CTE by half.”
Nowinski says in order for meaningful change, the football community needs a general acceptance that the sport can cause CTE.
“If we can get the football community to finally accept that the game of football causes CTE and especially the choices that coaches make in practice will directly influence whether or not their players will get CTE,” Nowinski said. “We have the opportunity to prevent it.”
There are ways to limit the amount of hits athletes sustain. In fact, two-thirds of head impacts in football happen in practice. Changing the way teams practice, without changing any in-game operations, will decrease the odds of developing CTE, according to Dr. Daneshvar.
“There really isn’t a one-size solution to these issues, but what this study provides us is a framework within which we can help make games safer for everybody,” Dr. Daneshvar said.
NFL players wear Q-Collar, which restricts blood flow from the head to provide extra cushioning around the brain. The NFL recommends the expanded use of Guardian Caps to increase protection during practice and offseason training, limiting the amount of tackling and head-to-head contact. Also, the league has position-specific helmets for linemen and quarterbacks. The NFL also funds research in helmet innovation and CTE research.
“If you think about the future of football, we have zero concerns about the pro game,” Nowinski said. “It’s more popular than ever. It’s making more money than ever because adults can do dangerous jobs if they want to, and they can expose themselves to a disease if they want to. The question is what do we do with the younger people? College football needs a real shot in the arm because there is no oversight and the players don’t have any rights. High school football can be made much safer and I’m hopeful it will. Especially with the oversight of educators in that. I don’t think tackle football should exist at all.”
While football players were at the forefront of most of the two studies discussed — and while it is one of the more prominent sports with CTE diagnoses — soccer has the most concussions of any sport. Furthermore, while football players are researched a lot, every contact sport has a level of risk associated and has a possibility of sustaining a head hit that can cause CTE.
“Ultimately your brain doesn’t care what hits it,” Dr. Daneshvar said. “If you’re getting hit in the head, whether it be through football or whether it be through hockey or another sport or whether it be as part of military service or as a victim of domestic violence, these principals that we learned from this study likely hold true for all of those cases.”