Aggression, Violence, and Mental Illness: Is There a Connection?

One persistent myth about people with complex mental illness is that they’re prone to violence and are a menace to society.

People who have disorders such as schizophrenia, schizoaffective disorder, bipolar disorder, and certain personality disorders face harassment, ostracization, and otherwise poor treatment due to the misguided belief that they pose a threat to the health, safety, and well-being of others.

Unfounded fears of people with mental illness can make it more difficult for these individuals to find and keep a job, participate in healthy relationships, and otherwise fully engage in a productive and satisfying life. Even after receiving psychiatric care, people continue to experience discrimination based on the fact have serious mental health problem.

Considerable research indicates that people with mental health disorders are victims more often than assailants. Unfortunately, scientific data cannot always overcome centuries of ingrained distrust.

A Brief History of Mental Health Stigma

Humanity has a long history of discriminating against – or actively persecuting – people with mental illness.

Wolf Rossler, a professor of clinical psychiatry at the University of Zurich (Switzerland) addressed “a millennia-long history of social exclusion and prejudices” a July 2016 article in the journal EMBO Reports.

Noting that the word “stigma” originates in the ancient Greek practice of physically branding criminals and slaves, Rossler traced a history of violence and oppression against people with mental illnesses that included a litany of horrific practices.

“For millennia, society did not treat persons suffering from depression, autism, schizophrenia and other mental illnesses much better than slaves or criminals: they were imprisoned, tortured or killed,” Rossler wrote. “During the Middle Ages, mental illness was regarded as a punishment from God: sufferers were thought to be possessed by the devil and were burned at the stake, or thrown in penitentiaries and madhouses where they were chained to the walls or their beds.”

The widespread persecution of individuals with mental illnesses continued into the 20^th century. Perhaps the most shocking display occurring during the Nazi years in Germany. In that period, Nazis sterilized, murdered, and/or sent hundreds of thousands of people with mental health challenges to concentration camps.

The Pervasive Impact of Mental Health Discrimination

In recent years, ongoing awareness campaigns and widespread educational efforts have hopefully improved public opinion of people who have mental health disorders – though research indicates that considerable work remains.

For example, a January 2009 study in the journal Lancet found that people with schizophrenia experience discrimination in nearly all areas of life. That study, which involved face-to-face interviews with 732 people with schizophrenia from 27 countries, reported the following:

• 47% of study participants reported discrimination when attempting to establish or maintain friendships.
• 43% of participants reported discrimination from family members.
• 29% reported discrimination when trying to find and/or keep a job.
• 27% reported discrimination in their intimate relationships.
• 72% said they concealed their mental health diagnosis from other people.
• 64% said anticipation of discrimination negatively impacted their efforts to apply for training, education, or employment.
• 55% said they ceased or reduced pursuing close relationships with others due to fear of judgment of their mental illness.

“There is no country, society or culture where people with mental illness have the same societal value as people without a mental illness,” Rossler wrote. “Structural discrimination of the mentally ill is still pervasive, whether in legislation or in rehabilitation efforts.”

An Overstated Risk, an Oversimplified Threat

Perhaps one of the most pervasive fears about people who have mental illness is that they are likely to be violent. Marie E. Rueve, MD, and Randon S. Welton, MD, addressed this concern in a May 2008 article in the peer-reviewed journal Psychiatry.

“Most patients with stable mental illness do not present an increased risk of violence,” Rueve and Welton wrote. “Mental illness may increase the likelihood of committing violence in some individuals, but only a small part of the violence in society can be ascribed to mental health patients.”

To support this statement, Rueve and Welton noted that substance abuse is a much stronger predictor of violence than mental illness is:

• One study found that the prevalence of aggressiveness is 73% higher among people who have mental illness and co-occurring addiction than among people who do not engage in substance abuse (regardless of mental health status).
• Another study reported that people who had primary diagnoses of a substance use disorder (addiction) and a personality disorder were 240% more likely to engage in acts of violence than were people who had a mental illness but did not abuse alcohol or other drugs.

Rueve and Welton also reported that a direct association between mental illness and violence ignores myriad other factors that can raise a person’s risk for aggressive behaviors. These factors, they noted, include:

Environmental Influences

Studies that looked into a history of violence within a family and the placement of twins in either stable or disturbed adoptive homes found that environmental influences can increase the likelihood that a person with a mental illness will act violently.

Perceived Threats

Multiple studies indicate that impulsive aggression among people who have certain mental illnesses is not random, but a result of perceived injustice as well as related emotions such as fear and frustration.

Adverse Childhood Experiences (ACEs)

Studies show that disruptive experiences during childhood, such as abuse, problems in school, parental hostility, absence of maternal affection, and poor parental modeling are linked with elevated rates of violence or aggressiveness among people with mental illness.

These and other studies, Reueve and Welton reported, imply that a cause-effect relationship between mental illness and violence is an oversimplification of a highly complex matter. The continued influence of thousands of years of hostile responses toward people affected by various mental health concerns likely also contributes to discrimination today.

“The overall impact of mental illness as a factor in the violence that occurs in society as a whole appears to be overemphasized, possibly intensifying the stigma already surrounding psychiatric disorders,” Rueve and Welton wrote.”

An Elevated Risk of Victimization

There is one area where the link between violence and complex mental illnesses such as schizophrenia seems to be indisputable. But it’s not the area that what passes for conventional wisdom would have you believe.

Multiple studies across several years from communities throughout the United States demonstrate that people who have serious mental illnesses are much more likely than members of the general public to be attacked, assaulted, and otherwise abused.

A June 2016 background paper from the Treatment Advocacy Center included the following statistics about victimization among people who have schizophrenia and other complex mental health concerns.

Violence and Mental Health: Important Facts

• A National Crime Victimization Survey of more than 900 people who had severe mental illnesses found that the rate of victimization among this group was 11 times higher than among the general public.
• A study in Pittsburgh found that, in the 10 weeks following discharge from a psychiatric institution, people with serious mental illnesses were victimized nearly twice as often as others in their neighborhoods.
• A research effort that followed 172 people with schizophrenia in the Los Angeles area for three years revealed that 34% reported assault, robbery, or rape, which is significantly higher than the rates of these types of victimization among the general public. The researchers also found that the likelihood of victimization increased with the severity of the individual’s symptoms.
• In Baltimore, a one-year review of data about women who engaged in substance abuse found that those who also had schizophrenia had a significantly higher likelihood of being a victim of violent physical or sexual abuse.
• In 2002, a New York Times reporter found that staff at a board-and-care home in the borough of Queens coerced over 50 patients into unnecessary surgeries, allowing physicians to collect payments from Medicare.

This elevated risk of victimization – and the likelihood of misplaced blame – extend to one of the greatest public health threats in the United States today: the national epidemic of gun violence.

Guns, Violence, and Mental Illness

In a January 2023 article on the website of the American Association of Medical Colleges (AAMC), John Rozel, MD, Jeffrey Swanson, PhD, countered the oft-repeated statement that the problem isn’t easy access to firearms, but the prevalence of mental illness.

“Given that so many individuals have a mental health diagnosis and the large majority of those individuals are never violent, psychiatric illness is too blunt an instrument to serve as a useful indicator of violence risk.” Rozel and Swanson wrote.

Violence and Mental Illness: Additional Facts

• If serious mental illnesses “suddenly disappeared,” the rate of violence in the United States would decrease by only about 4%.
• The FBI has determined that only 25% of mass shooters in the U.S. had a diagnosed mental illness.
• Fewer than 5% of mass shooters had a history of involuntarily intake to a mental health facility or another mental health-related adjudication, which would disqualify them from legally purchasing a gun.

Rozel and Swanson also highlighted a May 2015 study in the Annals of Epidemiology, which found that the data does not support a causal link between mental illness and most acts of lethal or near-lethal violence.

“Associating mental illness with violence reinforces stigma and unwarranted fear of people with mental illnesses — people who need support to recover from serious brain-based conditions,” they wrote. “[M]aking such a case can lead to misaligned priorities, misdirected resources, and misapplied coercive interventions against people with mental illnesses.”