How many people get concussions and never harm anyone because of it.
Actually, there is a (for lack of a better word) disease (maybe condition?) that has been tied to NFL players with concussions and the inability to rationalize their actions. Junior Seau, before he committed suicide, wrote a letter saying he wanted doctors to examine his brain because he knew something was not right. From what I understand, they found something along the lines of chronic concussions damaging the part of the brain that allows a person to rationalize. Seau knew what he was doing was wrong but could not rationalize himself out of his actions. That's why he shot himself in the chest so that doctors could examine his pain.
I think there are a number of factors to this other than the use of a handgun.
1. He played the most physical position in the most physical game in sports
2. He was known to be using (addicted?) pain killers for his injuries.
3. He was a heavy (addicted?) drinker
4. He grew up in not the greatest part of Long Island.
The gun was only the means, not the reason. He wasn't some alter boy who found a handgun under his parents bed and shot up a school because he had a gun in his hands.
I guess the guns Charles Whitman used were to blame and not his mental state... Charles Whitman Autopsy