'Brain changes' seen in American football players
Some teenagers appear to show changes in their brains after one season of playing American football, a small study suggests.
You don't have to be a seasoned professional player to suffer from the effects of repeated bouts of concussion.
John Frechette's career in sport was a short one, but his family believes he suffered the effects for the rest of his life.
Alex South reports from Boston.
02 Dec 2014
- From the section US & Canada