Are people with mental health problems at increased risk of violent offending?

Are people with mental health problems at increased risk of violent offending?

Are people with mental health problems at increased risk of violent offending?


The Australian Government’s Australian Institute of Health and Welfare report (AIHW, 2015) includes data from over 1,000 prison entrants from all states and territories across the country. It states 49% of the prisoners surveyed reported that they have or have been told by a qualified medical professional that they are suffering from a mental health disorder. This leads one to question, are people with mental health problems at an increased risk of violent offending? This essay will begin by looking at what constitutes a mental health problem and how these problems are categorized by different regions. It will then explore the relationship between violent offending and certain types of mental health problems from biological, behavioural, and psychological disorders. Within the examination and discussion of the question ‘Are people with mental health problems at increased risk of violent offending?’ empirical research will be used to explore what links exist between these specific mental health problem areas and violent offences being carried out. It is intended that this essay will support and clarify the link between certain types of mental health problems and the increased risk the sufferers of the problems pose to the community through heightened rates of violent offending.

Mental Health Problems and the Law

The term ‘mental health problems’ is not a legal term, so this essay will begin by examining the different definitions available. This term can refer to behavioural disorders which include things like Oppositional Defiant Disorder (ODD), Attention Deficit Hyperactivity Disorder (ADHD); mental or neurotic disorders such as Hypochondria, Depression, Anxiety, and Obsessive Compulsive Disorder (OCD); or even biological disorders, which range from Dementia and Alzheimer’s disease to Schizophrenia and Bipolar disorders. There is not one set of definitions and guidelines used globally to classify these disorders, and this can cause confusion where different countries recognize some but not others. When discussing classification of mental health problems, Beth Wilson said it best with “Definitions of mental illness are notoriously difficult to draft. If they are framed too narrowly they deny services to people. If they are too broad they may result in unnecessary intervention.” (Wilson, 1995). There are two main classification standards used in the international community. First is the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), which is used predominantly in the USA and the UK, and defines a mental disorder as the exhibition in an individual of biological, emotional and behavioural, or psychological disorders or dysfunctions (American Psychiatric Association, 2000). Secondly, there is the World Health Organisation’s International Classification of Diseases (ICD-10), which is used throughout Europe and defines the term mental disorder as a generic term to explain obstruction of normal actions from a set of medically diagnosable behaviours of symptoms (World Health Organisation, 1992). In each section below where empirical research and data is used, this essay will make note of what classification system for mental health issues is being used, and will explain how these types of problems and disorders can increase the risk of violent offending occurring.

Mental Health Problems Linked With Significant Risk

The interest of this essay is not to look at whether there exist violent offenders with mental health issues, but instead the purpose is to determine if suffering from a mental health issue will increase your risk of offending violently. We can start to understand what links exist by looking at a recent 2015 study (Stevens, Laursen, Mortensen, Agerbo, & Dean, 2015) which set out to compare the violent offending rates of the Danish population after mental health issues had set in. In this study the research team began by taking a random sampling (25%) of the population, and after allowing for population controls and other statistical modelling, followed the participants from their 15th birthdays, the age of criminal responsibility in Denmark, until they started committing offences, if any. What their study resulted in showing was that males with any mental health issues were at a significant increased risk of offending with an incidence rate of 2.91, and are almost double as likely to offend violently – with an incident rate of 4.18. Whereas females had an incidence rate of up to 8.94 for violent offending. From these results, they concluded that the risk of committing violent offences was significantly higher when compared to the general population throughout a range of differing mental health issues which included Schizophrenia and delusional disorders, neurotic and stress related disorders and other mental health problems as classified by the ICD-10. They went on to discover that an even higher risk was present for subjects of the study who were suffering from two or more diagnosed conditions. This study shows that there is a clear heightened risk for violent offending once one or more mental health problems have begun to manifest (Stevens et al,. 2015).

Prior Convictions Indicators of Mental Health Problems

This conclusion, that there is a heightened risk of violent offending when one is predisposed to a mental health problem, is further supported with empirical evidence from a study in the UK which aimed to see if people with a high severity of mental health problems were at an increased risk of violently offending (Hodgins, et al., 2011). This study is a rare instance where both classification systems for mental health problems are followed. The problems they recruited for were major depression, broad schizophrenia, and bipolar disorder. The study examined the offending rate of 301 people who were experiencing these mental health problems, as classified by the ICD-10, in a particularly severe form for the first time. In their study, they captured sociodemographic information and other variables via self-reporting from the study participants, as well as asking the participants to undergo psychological and neurological testing for a diagnosis to be made per the DSM-IV. They also gathered further information from the participant’s criminal record if these happened to be available (Hodgins, et al., 2011). Their results showed that significantly more participants in the study had prior convictions for violent crimes, including robbery, sexual offences, and ordinary violent offences, when compared to their peers in the general population. At times these rates were double or triple those of their general population peers. For instance, the volume of men committing sexual offences in the study was 2.4% compared to just 0.8% of the general population and rates of women committing violent acts against other persons where 3% in the study and only 1.1% when compared to the general population. Hodgins et al. concluded that people who are susceptible to mental health problems can be at a much higher risk to commit violent offences than those who are not (Hodgins, et al., 2011).

The Dangers of Comorbidity

Now that we have discussed some evidence for heightened rates of violence from people exposed to delusional disorders like Schizophrenia, or neurotic disorders like bipolar disorder, we can look at what happens when someone is suffering from multiple problems at the same time. A longitudinal study from Sweden which looked at 422 hospitalized individuals with Asperger Syndrome or Autism Spectrum Disorder (ASD) from 1988 – 2000 found that 7% of those looked at in the study were convicted of either sexual offenses or violent nonsexual crimes (Långström, Grann, Ruchkin, Sjöstedt, & Fazel, 2008). The team of researchers used the ICD-10 and the Swedish national hospital register to find participants for their study. They looked at individuals discharged from the hospital network who met any diagnosis for ASD. While they concluded that their study does not specifically link ASD with a heightened risk of violent offending, Långström, et al. went on to find that when paired with two or more mental health issues, the study’s subjects’ rates of violently offending began to increase rapidly. 19% of subjects who suffered from any comorbidity offended violently. Those rates rose to a drastic 33% when ASD was paired with a personality disorder, and an incredible 71% when paired with substance abuse or misuse. While the study from Hodgins et al. showed that susceptibility to mental health issues compared to insusceptibility can raise the risk of violently offending (Hodgins, et al., 2011), this study shows that the pairing of mental health issues can drastically increase these rates even further (Långström, et al., 2008). This increases the danger of people with multiple mental health problems to commit violent offences.

Substance Abuse Skyrockets Risk Levels

To further explore the idea of increased risk when comorbidity is present, we can look at the work of researchers ran a longitudinal study from New Zealand (Arseneault, Moffit, Caspi, Taylor, & Silva, 2000). They followed a group of 961 people from age 5 through to 21 with check-ups every two to three years. The participants were followed regardless of their association with the criminal justice system or health network. They set out to test three theories, (1) that a violent offence might first be preceded by substance abuse, (2) that people with mental disorders might have excessive perceptions of threats and (3) if they had a pre-existing condition of conduct disorder as a child, that might explain their violent offences regardless of current mental health problems. Using the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders (DSM-III-R), the classification available at the time, they measured rates of mental health problems and compared these against official criminal conviction records and self-reported violent criminal activity. Their study concluded that participants who met the selected criteria for mental health problems were at risk of violently offending (Arseneault, et al., 2000). They noted that disorders such as anxiety rated quite low with violence as a single diagnosis, but rose again to heightened levels when another disorder was also present. Their study goes on to note that schizophrenia and substance abuse disorders rated considerably high for violent offences. These participants made up only 18.3% of the total sample, but went on to contribute 57.9% of the study’s court convictions for violent offences. The study found that individuals who exhibited schizophrenia or substance abuse were more likely to confirm all 3 of their theories (Arseneault, et al., 2000). Overall they concluded that a person suffering two or more of these disorders is 8 to 18 times more likely to commit a violent offence when compared to an individual without mental health problems. The results of the (Arseneault, et al., 2000) study are strikingly similar to the results of two previous studies (Tiihonen, Isohanni, Räsänen, Koiranen, & Moring, 1997; Hodgins, Mednick, Brennan, Schulsinger, & Engberg, 1996). These studies came to similar conclusions that, when compared to their peers in the general population, psychiatric ward dischargee’s are at a higher risk to commit violent offences. With so many similar results from different regions, it’s clear that there isn’t any regional bias applicable.


The studies presented above show that some types of mental health problems, including Schizophrenia and delusional disorders, substance abuse disorders, and bipolar disorder can significantly increase the risk of violent offending by themselves (Stevens, Laursen, Mortensen, Agerbo, & Dean, 2015Hodgins, et al., 2011). Similarly, there are some less intensive disorders such as ASD that might not have a significant increase in the risk of violence by themselves, but when paired with a secondary mental health problem the risk of violence can rise rapidly (Långström, Grann, Ruchkin, Sjöstedt, & Fazel, 2008). The general consensus regardless of the type of disorder is that once comorbidity or concurrent diagnosises are present, the risk of a person violently offending starts to increase (Långström, et al., 2008; Arseneault, Moffit, Caspi, Taylor, & Silva, 2000). Specifically the study results showed that people suffering two or more mental health problems have an increased risk of violence that can be 8 to 18 times higher than people without mental health problems (Arseneault, et al., 2000). This essay has clearly shown that severe mental health problems raise the risk of violently offending and even non severe disorders such as ASD can become volatile when paired with a secondary disorder. The evidence presented shows that people with mental health problems are at an increased risk for violently offending.