While I am told that Aspergers is NOT a mental illness, it certainly is a mental condition/syndrome that may be treated off-label with powerful drugs that "may improve specific symptoms — such as anxiety, depression or hyperactivity — that can occur in many children with Asperger's syndrome" (Mayo Clinic).
It seems that many other young men who go on a sudden killing rampage have also suffered from mental conditions/syndromes and may have been under some kind of medical care. But we hear very little about how that care (not the syndrome or condition) could have been a factor in causing the rampage.
A quick search of the Internet on "Aspergers drugs side effects" can inform you that kids with Aspergers are "often treated with antidepressant drugs such as fluoxetine (Prozac®, Sarafem®)." According to "My Aspergers Child" blog:
"It is important for parents to work closely with the youngster's health care provider and to fully understand how to monitor the youngster for side effects of antidepressant medication. In some kids and teenagers, these medications may increase suicidal thoughts and actions.
"Other side effects that should be reported to the youngster's health care provider immediately include the following:
- Aggressive or impulsive behavior
- Agitation or restlessness
- Increased activity level
- Increased chattiness
- Increased depression or anxiety
- Increased irritability
- Panic attacks
- Sleep difficulties
- Strange moods or behavior changes"
There is ample evidence and warnings from the FDA that certain antidepressants can increase suicidal behavior in teenagers. So medication -- or lack of medication -- may have been a factor in this and other similar cases. Especially if the medication is prescribed off-label by GPs with little or no experience with mental illness. Pharma companies have pushed these inexperienced physicians to prescribe drugs that should only be prescribed by mental health experts, IMHO.
There is a connection between this line of inquiry and pharma marketing. I just alluded to drug companies marketing anti-psychotic and antidepressants to GPs. Direct-to-Consumer (DTC) advertising also is a factor in the increased use of these medications, but also helps explain why we don't hear more debate about the role of Rx drugs in murderous/suicidal ramages. Most of the news we have access to -- such as the nightly news programs -- are funded to a large extent by drug company ads. While these news sources go on and on speculating about increasing the regulation of gun ownership, none that I know of speaks of closer regulation of anti-psychotic and anti-depressant drugs. There is, however, more focus on mental health in general, but most of the focus is on mental health practitioners, not the drugs they may prescribe.
Neither mental conditions, prescription drugs, nor guns alone causes these tragedies, but the combination of the three greatly increases the odds of their occurrence.