Another in our series of discussions about the Newtown massacre, the focus this time on the link between mental illness, particularly among young men, and violence. In the wake of the nation's latest mass killing, there have been calls for more access to mental health services and more intervention. But are such incomprehensible tragedies predictable and preventable? And what disorders are at their root? Our guests: Midday contributors Dr. John Cmar, of Johns Hopkins University and Sinai Hospital, and Dr.