The point is that you cannot tell which way the arrow of causation is pointing.
Let me try to be a little clearer. Nearly all troubled individuals will be prescribed "big pharma drugs". A very small percentage of those troubled individuals will become mass murderers.
So, why should we believe that they became mass murderers because they took the drugs instead of because they were very troubled individuals?
It could be equally possible that a number of troubled individuals took the drugs and did not become mass murderers because the drugs worked.
I think that the indiscriminate drugging of large numbers of pubescent males has created these monsters. We are not only treating the troubled we are creating zombies... zombies that see the “fame” in doing something like this.