Violence, Mental Illness and Substance Use

  English PDF | More Fact Sheets

Many people fear violence, particularly violence that seems random or unpredictable. We often deal with this fear by avoiding people or situations that we believe might lead to violence. We see mental illness, substance use and violence connected often—in the news, on TV shows, and in movies.

This connection can fuel fear and this fear of violence can be a driving force for negative attitudes toward people with mental illnesses and substance use problems. But is the fear founded? The relationship between violence, mental illnesses and substance use is more complex than we see in the media, and it’s as reflective of our communities as it’s reflective of our individual experiences.

Many different factors increase the risk of violence. These risk factors may be found in our communities, such as exposure to violence (for example, seeing people commit an act of violence or knowing people who have experienced violence). Community factors (like safe and affordable housing), economic factors (like your income), and personal experiences (such as a history of violence and physical abuse) also play a role. Finally, violence may be influenced by individual characteristics like age or gender. These factors are the most important in predicting violence.


Violence and mental illnesses

While we often use the umbrella term of ‘mental illness,’ it’s important to recognize that individual mental illnesses are different. They each have different symptoms and affect people’s lives in different ways. Mental illnesses are also on a continuum. Not all mental illnesses are serious or severe. Two people with the same diagnosis can have two very different experiences.

We do know that mental illnesses on their own are not a good way to predict violence. The relationship between the two is complicated and affected by many different factors—in fact, other factors may be more important than mental illnesses. Some studies have found little evidence of a relationship between mental illnesses and violence. In a large US study, the risk of violence among people who experienced a serious mental illness without a co-existing substance use problem was about the same as the general population over the next three years.

Other studies do show a small relationship between some features of mental illnesses and violence. There may be an increase in risk of violence related to specific symptoms of schizophrenia or psychosis—symptoms like believing someone is out to harm you (a kind of delusion) or sensing something or someone is telling you to do something harmful (a kind of hallucination). The risk of violence decreases with proper treatment and management.

There are two important points to remember when we talk about this research. First, this increased risk represents only a small percentage of violence in our communities. Schizophrenia affects about 1% of Canadians. Risk of violence is only linked to two of many symptoms—not all people living with schizophrenia will experience these specific symptoms—and is related to poor treatment. So the risk of violence is a smaller portion of that 1%. Second, other factors like past experiences and communities still have a greater impact on risk of violence than mental illness. It’s estimated that 3% of violent crime in Canada is related to mental illnesses, so it’s clear that mental illnesses on their own don’t have a large impact on violence in our communities.


Violence and substance use

Substances include alcohol and other drugs. Evidence shows that the risk of violence may be higher among people who experience co-existing mental health and substance use problems. There may be a link between intoxication or use and violence. In Canada, it’s estimated that 7% of violent crime is related to substance use problems.

However, the substance itself may not always be the problem. Substance use can affect personal relationships, and conflict may lead to an act of violence. Substance use can also increase the likelihood of exposure to violence or victimization. But even though the combination of serious mental illness and substance use is a greater risk factor than either on their own, they are still affected by many other social factors, community factors, and past experiences. To learn more about substance use and why people might use substances, see the Understanding Substance Use info sheet at


Violence and our communities

Community factors play a significant role in violence. For example, poor housing and income disparities increase the likelihood of exposure to violence, and increased exposure to violence increases the likelihood of committing violence. People who experience a mental illness or substance use problem are more likely to be affected by inadequate housing and inadequate income, so they may be more likely to be exposed to violence. This complicated relationship needs to be addressed at the community level.

Victimization or exposure to violence may also be important risk factors in committing an act of violence. People who experience a mental illness are more likely to be victims of violence than the general population. Research shows that risk of victimization may actually increase the risk of committing an act of violence. Also, exposure to violence and trauma increases the risk of developing mental health or substance use problems in the first place, which increases the risk of more exposure to violence, creating a vicious cycle.

Health and community conditions are strongly linked. You can’t take one away from the other. If you want to understand why a health condition may affect risk of violence, you also have to understand how community factors affect risk of violence and how these different health and community factors might interact with each other.


What does this mean for me?

Many of us have questions around the risk of violence because we want to be safe. But the risk of violence stemming from mental illnesses or co-existing mental illnesses and substance use problems is low and involves factors that stem from our communities rather than a single individual. If 3% of violence can be attributed to mental illnesses and 7% of violence can be attributed to substance use problems, we’ve only accounted for 10% of violence in our communities. That means 90% of violence isn’t tied to mental illnesses or substance use problems. Most violence in society would still exist if we found a way to eliminate mental illnesses or substance use.


What does this mean for people who experience mental illness or substance use problems?

Fear can strongly influence how we think and act. For people who experience a mental illness or substance use problem, the public’s fear of violence can have a huge impact on their well-being. Here are a few examples:

  • People may avoid or discriminate against someone with a mental health or substance use problem. This not only affects opportunities to fully participate in society like all of us deserve, but also impedes recovery. It’s difficult to get better when people treat you like you’re dangerous

  • There may be more support by the public for forced legal action or coercive (against your will) treatment strategies. Forced legal action or coercive treatment can be very traumatic and can make people feel powerless

  • Patients in the forensic mental health system (a part of the mental health system that deals with both mental health and the legal system) may be automatically considered ‘high risk,’ which may reduce their access to recovery supports

  • We may fail to recognize the significantly high rates of violence committed against people who experience a mental illness or substance use problem and the complicated community factors that may contribute to increased violence against this group of people


Where do we go from here?

Work towards healthy communities—The well-being of our communities influences violence. When we address factors like unequal access to income and housing, inclusion, discrimination, and violence in our communities, we’re reducing the risk factors associated with violence. This may be more effective in the long-term than trying to identify and prevent violence after people experience multiple risk factors. As neighbours, we can be inclusive and say ‘yes in my back yard.’ As community members, we can share different perspectives and speak up when we see exclusion or discrimination. As voters and policy-makers, we can support policies and initiatives that improve living conditions for people who experience mental illness or substance use problems.

Improve treatments for concurrent disorders—When we look at risk of violence as an issue of treatment, we can see that it’s really a health problem. People who experience co-existing mental illnesses and substance use problems often find gaps between the mental health system and the addictions system. For example, mental health programs may require sobriety, even though substance use may be tied to a mental health problem. It’s difficult to think about recovery when the system may not consider all of your needs holistically.

Look at the role of the media—The media influences the way we understand the world. Some do challenge stereotypes, but news reports, TV shows and movies still use violent or ‘psycho’ stereotypes far too often. Media reports also tend to sensationalize any psychiatric history when they report on a crime, whether the two are related or not. They also depict the uncommon case more often than the common case of violence. Sensational stories are memorable and people consume more news when something is presented as a threat, but they don’t reflect our evolving understanding of mental health and substance use.

Any violence, for any reason, can be difficult to deal with. However, we have to consider the evidence. Avoiding or discriminating against people based on assumptions or stereotypes doesn’t protect us from violence. It may actually perpetuate violence—a community that excludes is an unhealthy community, and an unhealthy community may have a greater influence on violence than any diagnosis. The good news is that healthy communities do much more than address factors of violence. Theyimprove every community member’s well-being. Healthy communities come down to respect, inclusion, and equality. They give everyone a voice.