Again, it's a faulty figure because the you're looking at a population of data where the family is giving the brains to the scientists because they suspected the player had CTE. So there's a sampling bias involved with that figure. However, it is surprising that many players have CTE out of a population that were suspected to have it.
The other issue here is that we still don't know what exactly causes CTE. For instance, female college soccer players are supposedly far more likely to suffer concussions than male NFL football players. And to my knowledge there has not been a CTE issue with former female college soccer players. There would still be some correlation between CTE and football, but it would be interesting to see exactly what in football is causing this while that is not going on with soccer.
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