We've seen a rise in problems related to head injuries with football. It's no real surprise that some of the same problems may be seen in action sports athletes who have suffered head trauma over the years.
It's great that we are finally seeing some dialogue on the subject. Even movies like "headgames" from a few years ago addressing the subject. Unfortunately it's something we still know little about and likely something we will be seeing more of as time goes on.
Several new outlets including the New York Times reported on the CTE findings today.
http://www.nytimes.com/2016/05/25/sports/dave-mirra-cte-bmx.html?smid=fb-nytimes&smtyp=cur&_r=0