Research performed on high school athletes over seven years by scientists at Purdue University studying football and women's soccer players noted that for both sports, "about half the team is experiencing these kinds of things, these kinds of changes [in brain activity]. Some of them heal, some of them don't by the time the begin playing their next season."
The researchers are working towards creating better equipment to protect the head from high force impacts. "You're not going to change the game. You're not going to get rid of the game at least, so how can you make changes and so how can you make changes that keep the spirit of the game there, keep players enjoying, keep fans enjoying the game; but at the same time be safe."
Great to see researchers working towards making sports safer. I was surprised to hear that the percentage of football and women's soccer players with recorded changes (many temporary) in brain activity was the same. Would be interesting to know what percentage of non athletes would have registered changes in brain activity over the same time period as well.