by Mark Halstead, MD (Director, Sports Concussion Clinic & Medical Director, Young Athlete Center)
A recent study that was published in the medical journal JAMA entitled "Clinicopathological Evaluation of Chronic Traumatic Encephalopathy in Players of American Football" by Dr. Jesse Mez and colleagues at Boston University once again elevated the attention of the nation to ever growing concerns about the sport of American football. I witnessed report after report published online and featured on news and sports networks about this article and I felt it was necessary to talk the readers of this blog through it a bit to give you a hopefully balanced perspective about what this study tells us, what it doesn't tell us, some take away points and hopefully where we all need to go from here.
First, this study is a case series. What that means is a group of individuals with a known condition, in this case patients who were exposed to the sport of American football, had their brains evaluated after they died and were evaluated for a condition known as chronic traumatic encephalopathy, also commonly referred to as CTE. This is not a type of study that is often referred to as the gold standard study called a randomized controlled trial, where a group of patients are chosen randomly so that one person would play football, the other does not and then follow them to address who ends up with CTE down the road. Obviously this type of study is not practical for this type of condition as it would take an extremely long time to do as we'd have to wait until all the players died and hopefully keep any other variables that could account for CTE to a minimum. Another type of study that would be preferred and more practical is a case controlled study where we compare the brains of individuals(ideally with similar age/sex/race, etc) who had exposure to football and others that did not and see how many of each group have CTE. That also was not how this study was done. Because of that, it limits some of the conclusions we can draw about the findings in the study.
So what is CTE? CTE is a condition where there is an abnormal accumulation of tau protein in specific areas in the brain. It actually took until 2015 for a consensus group sponsored by the National Institute of Health to come up with an agreed upon definition of what actually defines CTE from trauma itself. Why is this important? Well, there are several other medical conditions out there that can build up tau in the brain including the commonly known problem called Alzheimer's disease. Interestingly a recent study in 2016 also found abnormal tau in the brains of patients with epilepsy, which is a condition where the patient suffers from seizures, in individuals as young as 4 months! If we don't have a way of distinguishing these conditions from each other, then it is much harder to determine potential cause and effect.
The modern day definition of CTE has been referred to by other names in the past, such as dementia pugilistica and the punch-drunk syndrome, and was first described and studied in boxers. It has only been in the last decade or so that attention has been raised about this condition existing in other athletes. I bring this up as this problem has been known for close to 100 years and I certainly do not deny it's existence. The problem we currently have is that we can only diagnose CTE after someone has died. This means we also currently don't have a way to determine that if someone who is suffering from a particular problem or symptom while they are alive, whether or not that is related to potential CTE findings in their brain, or something else and I will come back to this a bit later.
So what about the findings of the study itself? First, 81% of the brains examined in this study were obtained through the next of kin approaching the Brain Bank around the time of death. I will come back to this when we talk about the results affecting those who only played high school football. Second, the group obtained information about concussion history primarily through information provided by the next of kin through questionnaires. This may limit some of the accuracy of the data information from the history that was obtained. Certainly I've been involved with many patients who provide one story of the events and a family member may provide a very different interpretation. Third, the study talks about discrepancies in the interpretation of the brain findings were solved by discussion and consensus of the group. We don't actually know how many cases there were that resulted in discussions. If it is high, that could be concerning, and would lend itself to the consideration of an outside independent evaluator.
So the focus in the media was the fact that CTE was found in 110 of 111 (99%) of former NFL players, 48 of 53 (91%) of college players, 7 of 8 (88%) of former CFL players, and 9 of 14 (64%) of semiprofessional players. These were all players who played at a minimum of one game in that level of sport and that was the highest level of sport attained. Obviously those are some eye-popping statistics.
However, in the age group I deal with the most, high school aged athletes and under, CTE was found in only 3 of 14 (21%) of individuals who did not play beyond high school. In these former players, the 3 that were found to have CTE all had the mildest form. In those that stopped play prior to high school, none (0 of 2) were found to have CTE.
Why is this important? First, this would imply that 4 out of 5 players who play football through the high school level are unlikely to develop CTE, and if so, it is the mildest form possible. Granted, these are small numbers when looking at these statistics (only 14 total patients) but likely that 21% they found with mild CTE is likely lower since this was a self selected sample.
The frightening thing to me about this finding is not the high number who did NOT have findings of CTE. The concern to me is that 11 of 14 of individuals in this study likely had their brains donated because the family had concerns the person had CTE, yet they didn't. Why is that important? It means that the vast majority of these individuals likely had some other condition, very likely a common mental health issue such as depression or anxiety, that was likely not recognized, not evaluated, not treated, or attributed to being CTE. We have created great fear in this country about the prospects of getting CTE by playing football or having had concussions. I routinely hear former athletes saying they have CTE, including young athletes. My concern is we have created a problem where former athletes who had concussions now are thinking all of their problems are because of possible CTE or their concussions, and in reality they may have depression or anxiety or some other mental health issue and are avoiding evaluation or treatment. We already have a problem with mental health issues being a large stigma to patients and especially athletes seeing it as a sign of weakness and denying it. We also have a huge discrepancy in health care coverage and access to mental health professionals to patients in this country.
So I don't want this to be something that people feel I am endorsing football or the NFL. I am not. I am also NOT saying that you cannot get mental health issues or problems from repetitive head trauma. It is possible. But perspective is needed by all. I also am NOT endorsing tackle football in young athletes. I am of the belief tackle football is not the best option for kids under 12.
I would let my boys play if they wanted to (currently they don't). Football is a violent sport and many kids do get hurt, as they do in other sports. Some sustain serious orthopedic injuries, some sustain concussions. But I also have young patients doing extreme sports, riding bulls, participating in motocross (before they can legally get a drivers license), and there are high risks there as well. I could easily pick on those sports as much as is done with football. But those sports aren't on TV multiple days a week in the fall garnering billions of dollars in revenue. So I get the attention to football.
Some other concerning/interesting parts of the study....
1.The patients with mild CTE were 5 times more likely to die from suicide than those with the most severe form of CTE. Why? That doesn't make sense with what is talked about with this condition.
2. The most severe form of CTE was found in those that started football at an older age (10-14) than those with the mildest form (8-14). Raises doubt to the studies that have argued that younger starts of football are more concerning. This finding doesn't make a lot of sense unless those with mild CTE stopped football earlier and just didn't have the continued exposure. Clearly this study implies a significant dose response to developing CTE.
3. There were a much higher number of former military veterans in the severe CTE group (30%) compared to only 11% in the mild CTE group. Probably some coexisting contribution from military exposure such as blast injuries. The military has been investigating traumatic brain injury as much as is done in the sports world.
4. Those with the mildest CTE died at an average age of 44, those with severe CTE died at and average age 71. Wait...what? We know that tau deposition can increase with age. That may account for some of that. But why are patients with mild CTE dying, on average 3 decades sooner than those with severe CTE. In fact, the study broke the CTE into stages and those found to have CTE stage 1 (the mildest form) died, on average, at age 36....stage 2 at age 49, stage 3 at age 67 and stage 4, the most severe, at age 76! Compelling and interesting data.
5. The study found behavioral or mood symptoms at a slightly higher rate (96%) in the mild CTE group than the severe CTE group (89%).
6. Substance abuse disorders were present in 67% of patients with findings of mild CTE.
So what to take away from this. Your likelihood of developing CTE if you only play football through high school is low, and if you develop CTE it is mild. We still don't know what the CTE findings actually mean for that person while they are alive. If mild CTE patients are 5 times more likely to commit suicide, is it because of the CTE, or because of fear of the having the problem, or from something else. We don't know. We still have a lot more research to do about this condition. We still have a culture to change of getting kids to stop playing through possible concussions and coaches/parents/athletes recognizing that their own health is more important in the long run than the game in which they are participating. Thanks for reading.
Note: The above post is the opinion and interpretation by Dr. Mark Halstead of this recent study and does not reflect the opinion of all physicians at St Louis Children's Hospital or the Young Athlete Center.