Not Every Mass Murderer Is Insane, Study Says

Read: We Spoke to a Psychologist About Hollywood's Depictions of Mental Illness

A study released Monday coins a new term to explain how some people commit extremely violent crimes despite not being mentally ill.

Researchers at the University of Missouri School of Medicine presented the concept of "extreme overvalued belief" in their new work, which looked closely at the case of Anders Breivik, the Norwegian terrorist who killed 77 people, many of them young, in 2011. The authors argue Breivik fell victim to extreme overvalued beliefs in his attempt to "save Europe from multiculturalism" while claiming to be a "savior of Christianity."

Lead author Tahir Rahman told the MU Department of Psychiatry he hopes the "new term will help forensic psychiatrists properly identify the motive for the defendant's criminal behavior when sanity is questioned." He added that these extreme ideas are usually shared by people with similar cultural or religious beliefs.

While Rahman maintains that people with mental illnesses may be more vulnerable to developing extreme beliefs, "amplification of beliefs about issues such as immigration, religion, abortion, or politics also may occur through the internet, group dynamics, or obedience to charismatic authority figures."

Basically, just because someone is in decent shape mentally doesn't mean his or her extreme ideas about the world can't inspire senseless acts of barbarism.