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Mental Illness and Violence

Why a psychiatric diagnosis tells us little about who will hurt others

At age 22, Nina's future looked bright. Fresh out of college with a stellar G.P.A., she was one of the lucky few to land a job at a fast-growing computer company located in the center of Silicon Valley. While she missed her friends and family still living on the east coast, she keeps in regular touch with them via email and Skype. While the pressures of a fast-paced, first job and cross country move are stressful, she at first seems to be handling it well. When the long distance takes a fatal toll on her relationship with her boyfriend, things gradually change., used with permission
Source:, used with permission

It’s Nina’s sister who first notices something is amiss. Nina’s voice on the phone loses its characteristic expressiveness and becomes flat and distant. She complains that her food tastes funny; her friends chalk it up to west coast versus east coast taste buds – at least until she shares with them that jealous coworkers at her new company are poisoning her in order to sabotage her work performance.

To concerned friends and family, the evidence Nina offers to support her conspiracy theory seems vague and doesn’t add up; for example, she attributes the fact that she doesn’t feel well (has trouble concentrating, feels “strange,” and doesn’t have much energy) as evidence that poison has entered into her body. A missing yogurt placed in the office refrigerator is offered as evidence of food tampering. She claims mysterious clicks on her office phone are due to secret monitoring of her coming and going so scheming coworkers can sneak into her office and spray a toxic substance that will cloud her brain.

Nina is constantly afraid. She loses thirty pounds, refusing to eat anything while on company property (which is often 12 or more hours a day). She worries that “they” will find out where she lives and begin tormenting her there. After the night crew discovers her wandering the halls, crying and pleading with “the company people who are whispering and threatening to kill me” to stop, she is hospitalized and diagnosed with schizophrenia.

The Suffering in Psychosis

In her mind, Nina is living in a war zone where she is constantly plagued by hidden enemies. They track her. They torment her. They sabotage her work. They have even threatened her life. And, yet, like the vast majority of psychotic individuals, she has never harmed another human being. Research continues to demonstrate that mental illness is low on the totem pole when it comes to violence risk factors; a study published in the American Journal of Public Health found that fewer than 5 percent of the 120,000 gun-related killings in the U.S. between 2001 and 2010 were committed by people diagnosed with mental illness.

But, you may be thinking, what about the people who are really sick? You know, the homeless woman you see arguing with an invisible tormentor on the street corner, or the glazed-eyed street preacher proclaiming himself to be the third coming of Christ.

First of all, these “poster children” for untreated mental illness are likely suffering from psychosis. Psychosis is not a mental illness; it is a symptom. It can occur in schizophrenia, bipolar disorder, severe depression, heavy or long term cocaine or amphetamine use, Alzheimer’s disease, brain tumors, and various endocrine disorders. Essentially, it is defined as a loss of contact with reality and is most commonly associated with hallucinations, delusions, and/or disorganized speech and behavior.

Nina’s belief that coworkers are out to get her in an example of a persecutory delusion, the most common type of delusion. Individuals experiencing persecutory delusions believe that they are deliberately being targeted for some kind of harm. For example, s/he may believe s/he is being cheated, spied upon, attacked, harassed, conspired against, or otherwise sabotaged in his or her daily life. When you consider how terrifying that experience must be, it’s a wonder more psychotic individuals don’t commit hurt someone. However, new research suggests that even when a violent act is committed by a mentally ill individual, the odds are it wasn’t preceded by either delusions or hallucinations.

The Bottom Line

Contrary to popular belief, the link between mental illness and violence is exaggerated and, in the majority of homicides, nonexistent. In the next article, we’ll take a look at those factors that are most likely to lead to a “perfect storm” where a mentally ill person does hurt someone else, often in a misguided attempt to protect himself or others.