David Epstein and Moheb Costandi Talk Causality, and Head Injuries in Sports

Information on head injuries continue to inundate the sports world. A couple of weeks ago, sincere questions began to surround the link between brain trauma and addiction. And weeks before that, sincere questions have surrounded the link between brain trauma and Parkinson's.

The sport's world has responded slowly, but pieces are being moved. In a study involving three Division 1 college teams, it was revealed that college players suffer more hits to the head during practice than during the games, leading the Ivy League to reduce the amount of full contact practices to 2 per week (the limit is five per N.C.A.A guidelines). As Purdue University notes, the changes are being written into law as well.

A new Indiana law requires student-athletes to be removed immediately from athletic activities if it is suspected they have suffered a head injury. In order to return to play, injured athletes must be evaluated and cleared by a health-care provider trained in head injury assessment.

In addition to Indiana, several states have passed laws governing the management of suspected head injury to school-aged athletes ranging from classes for coaches and referees to removal from play and evaluation by a physician trained in head injury assessment.

In addition, new studies are looking to catch concussions early. Researchers at the University of Pennsylvania think that a two minute reading test where numbers are arranged in zigzagging patterns read from left to right could be crucial for testing purposes. According to Dr. Laura Balcer in a brief piece for Scientific American by Erica Westly (it should be noted that mixed martial artists were involved in this study):

'Typically people can complete the test faster the more times they take it'...But the athletes who had experienced head trauma during their fights read the cards more than 11 seconds slower when they took the test a second time.

Fighters who had lost consciousness fared especially poorly, worsening by 18 seconds on average. Now Balcer and her collaborators are studying the test’s ability to predict concussions in athletes who play football and other contact sports.

What's interesting about Balcer's test is that it sounds eerily familiar to the sensory-motor tests used to measure the age of the brain, and how fast it is shrinking. After 30, the brain loses a quarter of a percent of its mass annually, and any shrinkage is exacerbated by alcohol, and even gender (a man's brain shrinks faster than a woman's). At least in those tests, the average time to complete them for ages 20-29 is 122 seconds. A scary thought is how many might be taking, say, 228 seconds to complete the tests, as that is the average amount of time it takes for a 60 year old to complete them.

Beyond alcohol and gender, and just plain age as factors in brain tissue loss, so are head injuries. But the 'how' and the 'why' are complicated. To what extent are head impact exposure and injury linked? That's the question on Dr. Jospeh J. Crisco's mind, who is currently studying the relationship between head acceleration, and impact location (is one factor more critical than the other?).

However, while the threat is real, how behavior is ultimately affected by brain trauma remains a tricky one. That was the topic raised by Dr. Robert Cantu in suggesting a link between brain trauma and addiction. Rather than articulate my own thoughts about the care required for such suggestions, I decided to ask David Epstein about the nature of causality between the brain and behavior. He was, as always, kind enough to provide more than just a few words (his quote in full after the jump).

"I would just say that we should be careful about assuming the causality from cross-sectional observations, which are momentary snapshots, not longitudinal studies that track an illness over time. We just have to be careful, because it's clear, as with many illnesses, that some people who appear to suffer similar traumas have different results. So what factors go into pushing someone to the drastic and tragic point that some of these athletes have reached? Is it brain trauma alone? Is it brain trauma mostly? I don't really know, and I don't think anybody does with high confidence.

We don't really know quite what those tau proteins do, but it certainly seems to be a bad sign when they show up. Think back to Owen Thomas, the Upenn football player who was found to have CTE after he took his own life and became, in Robert Cantu's words, "the most public exposure of this problem." Cantu also said of Thomas: "The CTE is never supposed to be there, but it was not at all dramatic in Owen ... Not enough was there to affect behavior." That's a pretty responsible statement on his part, if you ask me. I think the concern that some medical professionals have is that they don't went every athlete in a contact sport who has an addiction or depression issue to feel that their brain is damaged such that they're incurable and the only treatment is to end their life.

I think most experts in this field would be quick to say these tragedies are likely multi-factorial. It seems pretty clear now that the vast majority, perhaps nearly all, NFL brains that are examined post-mortem will show CTE. Why are many ex-players apparently leading normal lives? I recall reading that Boogaard's family felt his painkiller addiction began with a 2009 shoulder surgery. It would seem that there is evidence both that brain injury can contribute to addiction and that addiction can contribute to brain injury. And, in many case, like Boogaard's, some persistent cause of physical pain may also be a cause of painkiller addiction.

I had the pleasure of visiting with ex-NFL QB Ray Lucas when he was undergoing treatment for painkiller addiction, with the pro-bono help of a group of doctors called Pain Alternatives, Solutions and Treatments. Last I checked he was off painkillers, very much due to the fact that his pain was treated. He'd had plenty of concussions in his day, playing both special teams and QB, and it's anybody's guess whether some type of brain injury might have contributed to his addiction. But he's doing better now. It just seems like there's a mountain range of individual variation here, so we just need to be careful about assuming causality in any particular case, while at the same time staying really vigilant about covering the issue. It's that trick of medical writing, making sure you hammer home the importance, but not being overly conclusive prematurely."

The Guardian's Moheb Constandi (and neurophilosophy blogger extraordinaire) was kind enough to provide a follow up response to Epstein's opinion via email:

I agree with Epstein that we should be cautious about how to interpret Cantu's remarks. It's always hard establishing causal relationships, and I doubt that every athlete who sustains concussions will go on to develop an addiction or depression. It may well be the case that concussion contributes to, or increases the risk of, addiction and depression, but this remains to proven and it would be premature to reach such a conclusion.  

The more important point in all this, which we musn't overlook, is that concussions sustained on the playing field are a real danger, and can lead to traumatic brain injury in the long-term. From what I understand, the NFL tried to deny these claims. They may even have tried to cover up scientific evidence backing them up, and tarnish the reputations of the researchers involved (this was revealed by Michael Silver for GQ Magazine, if I remember rightly). The NFL and NHL have finally acknowledged that there are real dangers associated with concussions on the playing field, and realize that they have some responsibility toward their players. They really need to provide equipment that minimizes the risks involved, and do what they can to provide the best possible treatment for players who do sustain concussions. We can only hope that they're not being disingenuous, and that they'll do everything they can to address these matters.