According to research, those with mental illness — about 18 percent of adults, according to the Kaiser Family Foundation — are no more likely to commit violent acts. But the fact remains that when you look at the modern era of mass shootings — including but not limited to the recent horrific events in Las Vegas and Orlando, Florida — there are certain common mental health factors and motives that define the mind of a mass shooter, according to Alan J. Lipman, Ph.D., J.D., professor at the George Washington Medical Center and founder and director of the Center for the Study of Violence in Washington, D.C.