Why Mass Shootings Can’t Be Reduced To A Mental Illness Diagnosis

In the aftermath of violent tragedies like the recent mass shooting in Tumbler Ridge, B.C., a common panic-fueled and grief-stricken reaction is to rush to simple, tidy explanations. Mental illness, for example, is often used to make sense of what appears to be senseless.

The explanation is appealing because mass shootings feel shocking and sudden, and mental illness offers a way to wrestle with them and try to understand. But the reality is that although mental illness sometimes plays a role in violence, it’s rarely the most important factor.

Regardless, politicians proceed to call for improvements to the mental health-care system, sidestepping more difficult conversations about violence prevention. As a researcher at Simon Fraser University within the Crime and Violence Risk Lab who focuses on gun violence and violence risk assessment, I argue that framing mass shootings as a mental illness problem misrepresents the evidence, and redirects our attention away from the other psychological, social and structural conditions that increase the risk of violence.

Why mental illness is a poor predictor of violence

Most people living with a mental illness are never violent, and most people who are violent are not living with a mental illness. One estimate suggests that even if all mental illnesses were somehow eliminated, about 95 per cent of violent acts would still need to be explained.

In fact, people living with mental illness are themselves more likely to be victims of violence. And mental illness is much more strongly associated with suicide than violence, especially when guns are involved.

It shouldn’t be treated as a single explanation — it’s a broad label covering hundreds of conditions. Some symptoms of mental illness, like psychosis, are associated with a slightly higher risk of violence. But the vast majority of people experiencing these symptoms will never be violent.

The appeal of mental illness as an explanation is driven in part by stigma. It resonates with people because there’s a commonly held belief that those with mental illness are dangerous, despite evidence to the contrary.

In most cases, other risk factors play a much larger role in explaining violent acts.

Violence risk is about probability, not prediction

Research on violence shows that it rarely emerges from a single cause, but from the interaction and accumulation of multiple risk factors over time in particular contexts and situations.

Professionals who assess the potential for violence focus on specific risk factors — personal, situational and contextual characteristics identified through research — that help to understand someone’s likelihood for future violence.

Even those risk factors simply point to the probability of violence, not certainty.

Substance misuse and intoxication, antisocial traits and attitudes that support violence, experiencing victimization or past trauma, negative peer influence and access to lethal means like firearms are examples of risk factors other than mental health problems that are statistically associated with violence.

These factors often interact with each other and build up over time, potentially shaping motivation, lowering inhibitions and destabilizing decision-making.

Psychiatrists and psychologists involved in the investigation of the 1999 Columbine High School massacre in Colorado described perpetrators Eric Harris as a psychopath and Dylan Klebold as an “angry depressive.” They noted that Klebold likely would not have carried out the attack on his own. What proved important for attempting to explain his involvement was not depression, but the interaction between anger, grievance, negative peer influence and access to firearms.

This case illustrates how diagnosis alone explains little without paying attention to other factors like social dynamics and access to weapons.

The common pathways behind mass shootings

Mass shootings only make up about one per cent of gun deaths in the U.S., yet they tend to shape the overall discussion about gun violence. The risk factors and motivations involved in mass shootings vary by context (workplace, school) and differ somewhat from those involved in more typical violence.

The definitive role of mental illness in mass shootings isn’t clear, given how complex, unique and statistically rare these tragedies are.

Part of the challenge is that mental illness is defined differently across studies. Overall, severe mental illness appears overrepresented among mass shooters, and having a history of mental health problems, more broadly, is also common. However, rejection, despair, grudges and rage appear to be far more important in explaining why these attacks occur.

Mass shooters tend to be young white men who are socially isolated, struggling at work or in school, and experiencing a sense of alienation. Many report histories of childhood trauma, bullying and social rejection, or at least perceive themselves to have been repeatedly wronged.

Perpetrators may fixate on and ruminate about negative experiences, which can harden into grievances directed at groups or institutions that they feel wronged by. Violence, in this context, then seems justified and can offer a sense of power, revenge or recognition.

Some mass shootings are also tied to extremist ideologies and are intended to garner attention, communicate a message or assert identity within a movement. This may increase a perpetrator’s sense of belonging or purpose. Online environments can act as echo chambers that promote and accelerate radicalization, particularly when someone feels they have been rejected elsewhere.

Many mass shooters also develop an intense interest in weapons and “leak” their plans or grievances to others before an attack.

Recognizing these warning signs can help create opportunities for intervention. At the same time, many people who fit these descriptions will never be violent, highlighting the uncertainty involved in risk assessment.

The future of violence risk assessment

The uncomfortable truth is that we just don’t know for sure what leads to a mass shooting. But focusing on a single risk factor distracts from the many others that research shows are important to pay attention to before they lead to violence.

Preventing future tragedies requires a clearer understanding of how risk develops along a pathway to violence and early intervention to handle warning behaviours.

Viewing violence as a complex process is essential. Reducing it to cursory labels like “mentally ill” makes it harder to address.

Samuel Freeze does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.