In the summer of 2017, a major story about chronic traumatic encephalopathy, or CTE, broke in Boston. CTE is a degenerating brain disease that occurs commonly in football players. Dr. Ann McKee, a neuropathologist affiliated with Boston University, studied the brains of 202 deceased football players. Out of 111 former NFL players, 110 of their brains showed signs of severe CTE. The study did have a strong selection basis, as the brains were donated by families who suspected their loved one might have been suffering from CTE. Nonetheless, the numbers were striking. Of the 91 people who weren’t NFL players, 87% had CTE. These included Canadian Football League players, along with semi-professional athletes and some college and high school players. Sadly, 3/14 high school football players (who quit football after high school) had evidence of mild CTE, and 48/53 of the college players had more severe CTE.
CTE affects portions of the brain that control memory, cognition, executive functioning, and emotional control. Those with the disease frequently demonstrate poor cognitive functioning, confusion, aggressive behavior, dementia, depression, and suicidal ideation. Zac Easter is one example of a young man who suffered from CTE at an early age. Zac played football in Iowa from age eight until his high school graduation. At age 24, after suffering from chronic headaches, slurred speech, and depression, he committed suicide by shooting himself in the chest. An autopsy demonstrated that Zac had severe CTE. Zac’s parents are now advocating for better awareness of CTE amongst parents whose children play football.
The number of children playing football in the US isn’t trivial. More than three million kids between the ages of six and 18 play organized football yearly in this country. Regarding the risk of brain injury from football, a few points are worth noting. Even if a child never sustains a full concussion, repeated “sub-concussive” blows received during football practices and/or games are a major risk factor for CTE. In a typical game, linebackers can receive more than 50 such blows to the head. The Boston researchers also point out that there appears to be a dose dependent effect of head trauma and CTE; the longer a person plays football, the higher the risk of developing severe CTE. This helps to explain why many college football players already have significant CTE. If you start playing football in early grammar school, then you’ve been playing for more than a decade by the time college graduation rolls around.
A stunning experiment conducted out of the Wake Forest Baptist Medical Center in 2016 further supports these conclusions. Bahrami and colleagues measured the effects of head injuries sustained during a single football season on a group of 25 children, ages eight-13. In this IRB-approved study, the researchers distributed helmets with sensors to the children, measured the acceleration forces applied to the helmets over one season of football, and compared head MRIs utilizing diffusion tensor imaging (DTI) before and after the season. DTI is a relatively new imaging modality that evaluates white matter changes on a cellular level. In previous studies, DTI has been used to evaluate white matter integrity in people who have suffered traumatic brain injuries, such as war veterans. Microstructural white matter changes are important because they correlate clinically with neurologic problems, like memory loss and cognitive decline. Why bother mentioning that this study was approved by an IRB, or interval review board? Because off the football field, no one would ever agree to purposefully cause head trauma in children and measure brain changes over time.
The results of the Wake Forest study were shocking. The helmet data demonstrated that the children sustained about 10 significant head blows during every practice, and the force applied was about 45 G’s, similar to the impact sustained in moderate car crashes. Two children sustained concussions and were excluded from the analysis. The kids with concussions were excluded because the researchers wanted to specifically evaluate the brain effects of subclinical head injuries—the types of lower-impact blows that occur repeatedly on the football field that don’t result in any symptoms. The brain MRIs showed a dose-dependent relationship between head trauma and white matter changes in these young children. In other words, the harder and more often the kids were hit, the greater the white matter changes. These results are particularly surprising because the children were asymptomatic. Importantly, other studies have shown that axonal injury is sometimes reversible, but repeated damage over time leads to the formation of permanent white matter changes.
Dr. Bennet Omalu, the neuropathologist who originally discovered CTE, has equated full-contact football with child abuse. As a general pediatrician reviewing the stories and statistics presented above, I’m inclined to agree with him. As Americans, we have plenty of other sports to choose from. Why not pick the ones that don’t cause brain damage, or at least cause it less frequently?
This raises another important point: football isn’t the only sport associated with concussions. One study in the British Journal of Sports Medicine noted high concussion rates for rugby (18 times the average for all sports combined) and hockey (5 times the average), along with American football. Other studies have found high rates of concussion for rugby, hockey, soccer, basketball, and wrestling. Interestingly, a 2017 study published in the American Academy of Orthopaedic Surgeons found that female athletes were 12% more likely to sustain concussions than boys, and the highest rate of concussions was among female soccer players. The authors concluded that heading the ball, coupled with a lack of protective equipment and an “emphasis on physical play” contributed to the risk of concussion in these female athletes.
What should we take away from this data? Although I’m not suggesting that we enclose young athletes in bubble wrap or ban all sports, parents should think about these numbers when choosing athletic activities for their children.
In the near future, a blood test for CTE in living humans may become available, which will help to shed light on this daunting condition. Currently, there is still much we don’t know about the long-term effects of sport-related concussions, but one thing is clear: even if my children get angry with me for limiting their choices, I’ll do whatever it takes to prevent them from getting CTE.