Klaus,

It's hard to definitely make any statements regarding brain injuries. I know a guy who had one concussion and his brain is super sensitive to jostling and bumping. On the other hand, John Elway has had 21 concussions and his brain seems just fine. For those of you who don't follow football, he was a hall of fame QB for the Denver Broncos, a very successful business man and now he is the Executive VP for the Broncos.

Mark is right though in that your chances of developing a sensitive brain greatly increase with the number of concussions you get.