The Link Between crime and Violence

Mental illness and violence

Public opinion surveys suggest that many people think mental illness and violence go hand in hand. A 2006 national survey found, for example, that 60% of Americans thought that people with schizophrenia were likely to act violently toward someone else, while 32% thought that people with major depression were likely to do so.

Mental disorders are neither necessary nor sufficient causes of violence. Major determinants of violence continue to be socio-demographic and economic factors. Substance abuse is a major determinant of violence and this is true whether it occurs in the context of a concurrent mental illness or not. Therefore, early identification and treatment of substance abuse problems, and greater attention to the diagnosis and management of concurrent substance abuse disorders among seriously mentally ill, may be potential violence prevention strategies. Members of the public exaggerate both the strength of the association between mental illness and violence and their own personal risk. Finally, too little is known about the social contextual determinants of violence, but research supports the view the mentally ill are more often victims than perpetrators of violence.

In fact, research suggests that this public perception does not reflect reality. Most individuals with psychiatric disorders are not violent. Although a subset of people with psychiatric disorders commit assaults and violent crimes, findings have been inconsistent about how much mental illness contributes to this behavior and how much substance abuse and other factors do.

An ongoing problem in the scientific literature is that studies have used different methods to assess rates of violence both in people with mental illness and in control groups used for comparison. Some studies rely on "self-reporting," or participants' own recollection of whether they have acted violently toward others. Such studies may underestimate rates of violence for several reasons. Participants may forget what they did in the past, or may be embarrassed about or unwilling to admit to violent behavior. Other studies have compared data from the criminal justice system, such as arrest rates among people with mental illness and those without. But these studies, by definition involving a subset of people, may also misstate rates of violence in the community. Finally, some studies have not controlled for the multiple variables beyond substance abuse that contribute to violent behavior (whether an individual is mentally ill or not), such as poverty, family history, personal adversity or stress, and so on.

ARE THE MENTALLY ILL VIOLENT ?

Over time, there seems to have been a progressive convergence of mental illness and violence in day to day clinical practice. From early declarations disavowing the competence of mental health professionals to predict violence, there has been a growing willingness on the part of many mental health professionals to predict and manage violent behaviour. With the advent of actuarial risk assessment tools, violence risk assessments are increasingly promoted as core mental health skills: expected of mental health practitioners, prized in courts of law and correctional settings, and key aspects of socially responsible clinical management.

Many psychiatrists, particularly those working in emergency or acute care settings, report direct experiences with violent behaviour among the mentally ill. In Canada, for example, where violence in the population is low relative to most other countries, the majority of psychiatrists are involved in the management and treatment of violent behaviour, and 50% report having been assaulted by a patient at least once. However, clinical experiences with violence are not representative of the behaviours of the majority of mentally ill. Social changes in the practice of psychiatry, particularly the widespread adoption of the dangerousness standard for civil commitment legislation, means that only those with the highest risk of violence receive treatment in acute care settings.

Public perceptions of the link between mental illness and violence are central to stigma and discrimination as people are more likely to condone forced legal action and coerced treatment when violence is at issue. Further, the presumption of violence may also provide a justification for bullying and otherwise victimizing the mentally ill. High rates of victimization among the mentally ill have been noted, although this often goes unnoticed by clinicians and undocumented in the clinical record. In a study of current victimization among inpatients, for example, 63% of those with a dating partner reported physical victimization in the previous year. For a quarter, the violence was serious, involving hitting, punching, choking, being beaten up, or being threatened with a knife or gun. Forty-six percent of those who lived with family members reported being physically victimized in the previous year and 39% seriously so. Three quarters of those reporting violence from a dating partner retaliated, as did 59% of those reporting violence from a family member. In addition, many people with serious mental illnesses are poor and live in dangerous and impoverished neighbourhoods where they are at higher risk of being victimized. A recent study of criminal victimization of persons with severe mental illness showed that 8.2% were criminally victimized over a four month period, much higher than the annual rate of violent victimization of 3.1 for the general population. A history of victimization and bullying may predispose the mentally ill to react violently when provoked.

Assessing risk of violence

Highly publicized acts of violence by people with mental illness affect more than public perception. Clinicians are under pressure to assess their patients for potential to act in a violent way. Although it is possible to make a general assessment of relative risk, it is impossible to predict an individual, specific act of violence, given that such acts tend to occur when the perpetrator is highly emotional. During a clinical session, the same person may be guarded, less emotional, and even thoughtful, thereby masking any signs of violent intent. And even when the patient explicitly expresses intent to harm someone else, the relative risk for acting on that plan is still significantly influenced by the following life circumstances and clinical factors.

History of violence

Individuals who have been arrested or acted violently in the past are more likely than others to become violent again. Much of the research suggests that this factor may be the largest single predictor of future violence. What these studies cannot reveal, however, is whether past violence was due to mental illness or some of the other factors explored below.

Substance use

Patients with a dual diagnosis are more likely than patients with a psychiatric disorder alone to become violent, so a comprehensive assessment includes questions about substance use in addition to asking about symptoms of a psychiatric disorder.

Another theory, however, is that substance abuse may be masking, or entwined with, other risk factors for violence. A survey of 1,410 patients with schizophrenia participating in the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) study, for example, found that substance abuse and dependence increased risk of self-reported violent behavior fourfold. But when the researchers adjusted for other factors, such as psychotic symptoms and conduct disorder during childhood, the impact of substance use was no longer significant.

Personality disorders

Borderline personality disorder, antisocial personality disorder, conduct disorder, and other personality disorders often manifest in aggression or violence. When a personality disorder occurs in conjunction with another psychiatric disorder, the combination may also increase risk of violent behavior (as suggested by the CATIE study, above).

Nature of symptoms.

 Patients with paranoid delusions, command hallucinations, and florid psychotic thoughts may be more likely to become violent than other patients. For clinicians, it is important to understand the patient's own perception of psychotic thoughts, because this may reveal when a patient may feel compelled to fight back.

Age and gender 

Young people are more likely than older adults to act violently. In addition, men are more likely than women to act violently.

Social stress

 People who are poor or homeless, or otherwise have a low socioeconomic status, are more likely than others to become violent.

Personal stress, crisis, or loss

Unemployment, divorce, or separation in the past year increases a patient's risk of violence. People who were victims of violent crime in the past year are also more likely to assault someone.

Early exposure

 The risk of violence rises with exposure to aggressive family fights during childhood, physical abuse by a parent, or having a parent with a criminal record.