[Nelson69]

It's sort of silly but it's sort of not. The evidence suggests that a few really big hits doesn't do it, it's repeated medium sized head traumas that does. (ie: it happens to line men more frequently out of footballers) Quantifying the size of that head trauma is really key. Does it have to be a "hit?" I mean repeatedly hitting mogul runs put shock on your whole body, you may not hit your head but you're absorbing that up and down shock and moving side to side fairly abruptly; more so that you do just running around and your brain absolutely experiences some amount of that. Age might have a factor too, age when this trauma or shock happen.

I ski and snowboard and I'm not planning on stopping, I think the benefits outweigh the risks. I'd say that about most sports but I'm not about to let either of my kids play football or box.

We need to study this stuff a lot more.