Anti depressants
^^ This. If you're over 35, ask yourself: how many kids you grew up with were on Prozac, luvox, or paxil? There's way more now, I swear, even in the most liberal of schools you will probably find more kids on prescription meds instead of weed (and despite coming from a right-wing conservative family, I'd rather deal with the pot heads).
For those of you who don't know, my part-time job is with AMR as a paramedic. We do mostly inter-facility transfers, including taking psychiatric patients to Kahi Mohala. I have seen kids as young as 9 on meds and being transported with a diagnosis of "suicidal ideation", but early teens and young adults are far more common. When I was in high school, Ritalin was just starting to show up. Parents and teachers were mostly against it, questioning the need for a prescription to regulate behavior. Nowadays, it seems that these meds are over-prescribed. Granted, there are those out there with a valid need for it, but I think a lot of parents are turning to meds before thoroughly exhausting other options.
The drug lobby is arguably the toughest to fight. TV commercials now advertise how you can get your first prescription for free or how they will get meds to you even if you can't afford them. This should be raising some serious red flags, especially considering that Obama is looking at having more and more doctors render people mentally unfit to own a firearm. Those teenagers who have been put on meds as a knee-jerk reaction will have a record that will follow them and bar them from gun-ownership. If anything, there needs to be a way for us to get politicians to acknowledge the link between anti-depressants and violent behavior. They are the common denominator, not semi-auto rifles.