"In fact, the risk of post-concussion syndrome doesn't appear to be associated with the severity of the initial injury. In most people, symptoms occur within the first seven to 10 days and go away within three months. Sometimes, they can persist for a year or more." I've had two sports-related, one of which was during a basketball game. Once you start coming out of the fog (nausea, headaches, light sensitivity, vision issues, etc..) these symptoms come and go intermittently at least for me. The other adjustment is similar to coming back from an ACL injury; I was not as aggressive from fear of getting another one.
In hindsight, I think we've been baited into an argument just for fun. He probably knows the truth unless he's had multiple concussions himself. Has he posted here that the earth is flat, yet ?