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Dangerous games: brain injuries in sports

You don’t need to be a boxer or a football player to end up with a brain injury.

When did I realise I was never going to be an All Black? When Josh Kronfeld retired (he and I are the same age). The fact that I didn’t really play rugby is irrelevant.

The closest I have been to an All Black was at Eden Park a few years ago, when I found myself standing next to Steve Devine at a urinal. He will have no reason to remember this. Devine represented both Auckland and New Zealand, and retired from rugby because of the well-publicised effects of several serious head injuries.


Such knocks can happen in most sports, and not just obvious contact sports such as skiing, equestrian, wrestling and boxing. All these knocks have the potential to cause brain injuries, ranging from “asymptomatic subconcussive blows” (you’re not knocked out and no one can tell if you’ve been hurt) to traumatic brain injury.

Look at boxing. For more than half a century there have been calls to mitigate the effects of being repeatedly whacked in the head, and even to ban the sport entirely. After all, dementia pugilistica has been around for the best part of a century. Originally identified as a set of symptoms referred to as “punch-drunk”, it is typically found among boxers, particularly the Rocky Balboa-type sluggers whose style involves taking a beating to the head. Symptoms include motor deficits (problems with normal movement), confusion and mood disturbance.

It wasn’t until the 1970s that these deficits, though superficially similar to a range of other neurological problems, were identified as distinctly different – not just something we already knew about, but caused by repetitive head banging.

So, what’s going on? The inside of your skull is not as smooth or as padded as you might hope, and when your head moves fast in any direction, your brain can bounce around, causing stretching of the doohickeys (okay, axons) that are important for thinking. Repeated axonal stretching and squidging of things that shouldn’t be squidged, particularly if you’ve not recovered from a previous knock, have been suggested as the mechanism leading to chronic traumatic encephalopathy (CTE).

Rugby can be a tough game, but not as tough as, say, boxing, right? Boxers get knocked out all the time (it’s kind of a key performance indicator), but it’s less common in rugby. Contrary to what a lot of people think, you don’t need to be knocked unconscious to suffer a concussion. And when you’re concussed, you may not know it.

This is a hot topic in the world of American football. Following a series of high-profile tragedies, a lot of attention has been paid to investigating the possibility that the neurodegeneration that goes with CTE isn’t just a product of the rapid repetitive blows we see in boxing, but can also grow from less-obvious repeated trauma.

Until recently, the problem had been that identifying CTE involved looking at the brains of dead people. These days, Boston University is the place to go for this kind of stuff, and researchers have a battery of tests they can use on “live” specimens to check for evidence of CTE as well as the things that might be involved in helping it develop.

Genetics can play a part; CTE appears to be disproportionately common in people with the apolipoprotein E gene, so maybe that’s a risk factor. It also seems more common in some player positions than others and that may be related to the type and direction of blows. For example, boxers experience more rotational force, but American footballers get more straight-line knocks, and linemen (the “big” guys), among whom these problems are more common, take more blows to the front of the head. Time to strap an accelerometer to Richie McCaw.

Oh, for the record, Wellington beat Auckland that night … Just saying.