Researchers at the University of Missouri say mental illness may not always lead a person to kill innocent people.
In fact, they say labeling mass shooters as "psychotic" may give us a poor understanding of why a person would commit a horrific act of violence.
Instead, they say mass shooters might suffer from "extreme overvalued belief" which causes them to take extreme actions.
Researchers suggest a person with an extreme overvalued belief has an intense emotional commitment to it, which is why they may feel the need to act it out.
This study, “Anders Breivik: Extreme Beliefs Mistaken for Psychosis,” was published in The Journal of the American Academy of Psychiatry and the Law.
In some cases, extreme beliefs are radicalized by using the Internet. Investigators say that appears to be the case with Omar Mateen, who killed 49 people and injured many more in a shooting early Sunday morning at a gay night club called Pulse in Orlando, FL.
President Obama said in a news conference earlier this week that is was increasingly clear the killer "took in extremist information and propaganda over the internet. He appears to have been an angry, disturbed, unstable young man who became radicalized."
While this study has not been related to the Orlando shooting, Tahir Rahman, an assistant professor of psychiatry at MU and the study's lead researcher, said the internet can play a role.
“Certain psychological factors may make people more vulnerable to developing dominating and amplified beliefs,” Rahman said. “However, 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."
Rahman's study was focused on Anders Breivik, a Norwegian terrorist, who killed 77 people in a 2011 car bombing in Oslo and a mass shooting at a youth camp on the island of Utøya in Norway.
Breivik stated that the purpose of the attacks was to save Europe from multiculturalism.
A court-appointed team of forensic psychiatrists first diagnosed Breivik with paranoid schizophrenia.
However, a second team concluded that Breivik was not psychotic and diagnosed him with narcissistic personality disorder.
Breivik was sentenced to 21 years in prison.
“Breivik believed that killing innocent people was justifiable, which seems irrational and psychotic,” Rahman said. “However, some people without psychotic mental illness feel so strongly about their beliefs that they take extreme actions."
Rahman argues current clinical guides offer vague descriptions of alternative reasons a person may commit such crimes.
That is why he is suggesting the term ‘extreme overvalued belief' when psychosis can be ruled out.
“In courts of law, there are not clearly defined, standard methods of diagnosing insanity for legal purposes,” Rahman said. “This new term will help forensic psychiatrists properly identify the motive for the defendant’s criminal behavior when sanity is questioned.”
Going forward, Rahman said he hopes more research can be done to understand how these overvalued beliefs develop.
He hopes this research will help identify those at risk so mental health professionals can intervene before violent behavior occurs.
"We already warn our youth about the dangers of alcohol, drugs, teen pregnancy and smoking," Rahman said. "We need to add the risk of developing extreme overvalued beliefs to that list as we work toward reducing the violence often associated with them.”
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