Concussions, Back Problems, and Odd Statistics

Jonah Lehrer has a big article at Grantland on concussions in high school football that paints a fairly bleak picture:

The sickness will be rooted in football's tragic flaw, which is that it inflicts concussions on its players with devastating frequency. Although estimates vary, several studies suggest that up to 15 percent of football players suffer a mild traumatic brain injury during the season. (The odds are significantly worse for student athletes -- the Centers for Disease Control and Prevention estimates that nearly 2 million brain injuries are suffered by teenage players every year.) In fact, the chances of getting a concussion while playing high school football are approximately three times higher than the second most dangerous sport, which is girls' soccer. While such head injuries have long been ignored -- until recently, players were resuscitated with smelling salts so they could re-enter the game -- it's now clear that these blows have lasting consequences.

The consequences appear to be particularly severe for the adolescent brain. According to a study published last year in Neurosurgery, high school football players who suffered two or more concussions reported mental problems at much higher rates, including headaches, dizziness, and sleeping issues. The scientists describe these symptoms as "neural precursors," warning signs that something in the head has gone seriously wrong.

It's a pretty good read, as is usually the case with his stuff, but it leaves me wondering about a number of things. The biggest question is just how meaningful this really is, given the other big long Jonah Lehrer article I've read recently, on how it's damnably difficult to make clear determinations in medical science.

In particular, I wonder if the new research on concussions described in the Grantland piece isn't going to turn out a little like the back pain section of the Wired article:

The view afforded by MRI led to a new causal story: Back pain was the result of abnormalities in the spinal discs, those supple buffers between the vertebrae. The MRIs certainly supplied bleak evidence: Back pain was strongly correlated with seriously degenerated discs, which were in turn thought to cause inflammation of the local nerves. Consequently, doctors began administering epidurals to quiet the pain, and if it persisted they would surgically remove the damaged disc tissue.

But the vivid images were misleading. It turns out that disc abnormalities are typically not the cause of chronic back pain. The presence of such abnormalities is just as likely to be correlated with the absence of back problems, as a 1994 study published in The New England Journal of Medicine showed. The researchers imaged the spinal regions of 98 people with no back pain. The results were shocking: Two-thirds of normal patients exhibited "serious problems" like bulging or protruding tissue. In 38 percent of these patients, the MRI revealed multiple damaged discs. Nevertheless, none of these people were in pain. The study concluded that, in most cases, "the discovery of a bulge or protrusion on an MRI scan in a patient with low back pain may frequently be coincidental."

Now, obviously, some of the brain issues they talk about sound pretty serious, but at the same time, this is a new enough area of study that I wonder if they really have a solid enough baseline to draw conclusions. After all, kids have been playing high school football for decades without people particularly noticing lingering ill effects from that, but these brain and concussion studies are fairly new.

I suppose you could argue that advances in athletic training have made high school football players of today significantly stronger and faster than years ago, making concussions a bigger problem. I'm not sure this wouldn't be countered by a general improvement in overall safety, though-- football coaches twenty or thirty years ago used to do some crazy shit that they would never get away with these days.

I worry a little that this is part of the same general trend of panicking about the safety of things that aren't really that serious a threat. Kids are awfully resilient, often more resilient than they're given credit for. It might be that this sort of brain injury is less serious than the words "brain injury" make it seem. I think that before you talk about ending high school football, you really need the sort of baseline study you got with the back pain business: look closely at the brains of a lot of high school athletes who didn't get concussions, and a bunch of non-athletes as well.

I say not so much because of any deep attachment to high school football, but because I'm not sure it would stop there. I mean, you could probably make a case that there are lots of other problems associated with the culture of high school football, so that losing it wouldn't be that big a deal, but number two on the concussion list is girls' soccer, which isn't exactly renowned for its pernicious effect on society. And yeah, the difference between the two is pretty big, but it's not hard to imagine overprotective parents deciding that there's no level of concussion risk that is acceptable, at which point the only acceptable sports become chess and videogames (G-rated non-violent games, of course).

(This is a little like when car accidents or whatever are cited the "second leading cause of death among 18-21 year olds." Which sounds really scary, but you also have to recognize that something is going to be the second leading cause of death for any demographic group you choose, and there just aren't that many natural causes that kill 18-21 year olds. What matters is less the ordinal rank than the absolute rate. Unless, of course, you're deliberately trying to scare people in order to achieve some policy goal.)

I also end up wondering about those statistics, specifically why girls' soccer ranks so highly. The source of those numbers is probably one of the studies used for this compendium, which doesn't really clear anything up. Yeah, football is a clear (and unsurprising) outlier, but girls' soccer seems oddly high. What's particularly odd is that the concussion rate for girls' soccer is almost twice that of boys' soccer, which really makes no sense at all. Especially since the rates for basketball (the only other really clean sport pair) are comparable for both genders.

So, in the end, my impression of all this, as always, is that I'm really glad I don't work in medicine, where everything always looks like a hopeless muddle.

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I am not a physician or trainer, and my comments are based on my readings and my observations of my two kids experiences in sports over two decades: youth sports often have coaches with poor knowledge concerning the teaching of safe and effective techniques (let alone medical training of any type). When you need coaches and they are volunteers, you take what you can get.

That said, could the relatively high instance of concussions in girls soccer be related to poor heading techniques, plus necks that are smaller in proportion to their head size then their male contemporaries? Heading a passing hard kick into a goal can impart a lot of force to the head. The girls leg strength isnât an issue: they can really move the ball.

I am unaware of any studies on this but would be surprised if there were none.

I think this one is a little different from the back pain one since the players are essentially being used as their own control, via the imPACT (I forget the actual weird capitalization) test comparisons. The players are measurably worse cognitively post concussion vs. pre-concussion and the effect lasts about a week. It's possible that there isn't a lasting significant (in the nonstatistical use of the word) problem. If the brain lesions were the only diagnostic criteria or were what was being treated, then it would be more like the back pain thing, I think.

Re: girls soccer, might average height differences or style of play explain the difference with boys soccer? I could hand wave a just so story around how the boys are typically 6' vs 5'5" for the girls and this changes the angle of incidence for a headed ball, etc. I don't know what I'm talking about, obviously.

By brian ledford (not verified) on 11 Jan 2012 #permalink

I should also note that Google helpfully turned up this recent study of concussion rates, which gives very different numbers than Lehrer quotes or are at that link above. According to this study of 19,000 athletes in North Carolina, football is much less of an outlier compared to other sports, and boys' soccer is higher than girls'(33 per 100,000 for football, 23 for boys, 13 for girls). I haven't read it closely enough to see what they say about their numbers in comparison to other studies.

Regarding the self-referencing, do they test each individual athlete before the season, or are they comparing them to some expected baseline? I thought it was the latter, because the former seems impractical, but it's buried a couple of citations deep in the stuff I've looked at, and I don't have time to ferret it out.

from the grantland article:
"The concussed subject is set in front a computer and, for the next twenty minutes, run through a battery of cognitive tests. Because every player is also assessed before the start of the season â this is the baseline metric â the medical staff is able to measure the decline in performance triggered by the injury."

this might only apply to Mater Dei, though. Of course, this still has the sampling problem, since they are only retesting concussed athletes. We don't know how a nonconcussed but stressed or distracted teenager will perform.

By brian ledford (not verified) on 11 Jan 2012 #permalink

Well, we do look at brains every day in the MRI section, and most of them don't have any kind of damage (despite the symptoms the patient in question suffer from that leads their doctor to request a brain MRI scan). I haven't read the original research, because I don't care much about sports, but concussions sometimes do have lasting aftereffects.

I recently read of another confounding complication with the pre-season cognitive tests. Some students are now deliberately playing dumb while taking these tests, willfully under-performing to lower their score. So, if they DO get a concussion later in the season, they can try hard on the post-injury test and get roughly the same score, thus allowing them to keep playing.

Sheesh. If there's a protocol on this Earth that cannot somehow be gamed, I haven't heard of it yet.

By Emory Kimbrough (not verified) on 12 Jan 2012 #permalink

I once heard an argument that the problem with American football is that the equipment has gotten too good. Basically, yes the equipment does protect players but it also becomes a weapon and gives players a false sense of confidence. Basically, playing rugby is rough and can be brutal but statistically doesn't normally involve as severe injuries. I maybe wrong, but I do remember reading that was the case. On a personal note I played high school ball and a lot of back yard tackle football regularly until I was 19. My own observation was that the really frightening injuries, happened coached and with pads. Lesser injuries did occur with out pads...but they just weren't on the same level. Again, I realize one is an undocumented report and the other is anecdotal....

By Mike Olson (not verified) on 12 Jan 2012 #permalink

My brother-in-law is a HS baseball coach and his take on the higher injury rates are that kids are playing one sport intensely throughout their childhood, in hopes of catching the eye of college recruiters/scholarships. Young athletes used to do multiple sports, perhaps even taking up a sport in high school. Now, competitive high school teams are filled with kids who've been on travelling teams since elementary school.