One young man I met several years ago sustained a concussion while he was participating in football practice. His coaches and parents didn't think much about the "knock on the head," that is, until he sustained another concussion four months later. The second concussion wiped out his memory, and today, the former athlete is permanently disabled as a result. Had his parents and coach been aware of the destructive aspects of post-concussive syndrome, they would've taken all the appropriate preventions.
If you're a coach, or you're involved athletics, then you need to be aware of a free kit offered by the Center for Disease Control. Concussions are an all too common injury on the field, and repeat concussions are responsible for some of the most problematic brain injuries.
The Coaches Toolkit contains tons of information regarding mild TBIs and concussion, and includes a video featuring a young athlete disabled by concussion. You can either download it from the CDC website, or you can contact the CDC at 1-800-CDC-INFO to request your kit. .