A lot of people may be "medicating" away their consciences...
The Ego and Super Ego are there for a purpose...to control the ID....TO MAKE YOU DEPRESSED....
Removing the depression with meds...could release the ID... And that is exactly what these shooters seem to be...Pure ID gone wild...unleashed... (In Freudian Terms)
New drugs could play a big part in this phenomenon...
Although...in the South Seas Islands among the Bugis People...there was a phenomenon called "Running Amok"... (Yes that is where the phrase comes from)....
People who were "disappointed in life"...or greatly offended would "Run Amok" ...until killed by others in their village...
It was often a form of suicide...which seems to play a part in these recent shooting cases...strong suicidal tendencies...after some "disappointment" and unfortunately some people...usually younger... don't have the coping mechanisms to deal with these issues..
http://en.wikipedia.org/wiki/Running_amok