Professionals in psychiatric settings are accustomed to questions about violence. It is not an uncommon perception in the general population that individuals with psychiatric disorders are dangerous, i.e., that violence is more common among them than among others. Clinicians working in psychiatric emergency services are not unfamiliar with acute assessments brought about by acts of violence.
Lethal violence can be described as an ultimately violent act. Statistics on lethal violence are usually more robust than statistics on general violence since the concept is well-defined and acts of lethal violence will engage the public and the criminal justice system. The global homicide rate is about 6 per 100.000 (1). Rates vary widely across the globe, as seen in the figure from the United Nations 4th Edition of the global study on homicide (Figure 1). Methods-wise, firearms are more often used in North and South America, while sharp objects or other mechanisms are more common in Europe and Asia. (1) Globally, 90% of perpetrators and 80% of all victims of lethal violence are men.
Even though lethal violence has often been treated as a homogenous category in criminal research, previous researchers have recommended further subtyping into separate groups. Acts of lethal violence are multifaceted, and subgrouping is necessary to better understand these phenomena (2).
The United Nations utilizes three broad categories:
Homicide related to criminal activities (organized or unorganized crime) – accounts for approximately 25% of all homicides.
Interpersonal homicide (intimate partner homicide or homicide outside the context of family) - approximately 30% of all homicides.
Sociopolitical homicide (related to social prejudice or sociopolitical agendas) – approximately 9% of all homicides.
For about one-third of all homicides worldwide, categorization cannot be made due to insufficient information.
Trying to establish associations between mental illness and lethal violence is challenging in several aspects. Individuals with psychiatric diagnoses are not a distinct entity, seeing as psychiatric diagnoses range from anxiety and substance use disorders to bipolar and psychotic disorders. Operationalizing mental illness is a well-known obstacle since the concept covers everything from normal reactions to grief to severe psychiatric disorders. Taking these impediments into consideration, aggregated data from research on mental disorders and lethal violence can be summarized in the following.
The typical offender of lethal violence does not suffer from severe mental disorders that would presumably render the offender not guilty by reason of insanity (NGRI) (3, 4). The majority of offenders of lethal violence do not have a history of mental disorders (4-7). Mental illness does, however, increase the risk of committing homicide, especially among women (3, 8, 9).
Intimate partner homicide shows different characteristics than homicide related to criminal activities or sociopolitical agendas. Women represent two-thirds of all victims of intimate partner homicide, and the rate of intimate partner homicide tends to be more stable across countries than other forms of homicide (1). Perpetrators of intimate partner homicide where the victim is female (femicide) rarely have been diagnosed with mental disorders (10, 11) but show psychopathic traits to a higher extent than offenders of non-lethal intimate partner violence (12). However, perpetrators of femicide where the offender and the victim have mutual children might consist of a subgroup with higher prevalences of mental disorders (13).
Substance use disorders and personality disorders are the most common psychiatric disorders that appear among offenders of lethal violence (3, 4, 14-16). There is an association between psychotic disorders and homicide (3, 4, 15-19). The impact of the psychotic disorder itself on the risk of homicide is debated, and excess risk has been suggested to be mediated by co-existing factors such as substance use disorders (16-18, 20, 21). The risk of offending with lethal violence for an individual with a psychotic disorder is highest during the first episode of psychosis (22, 23).
Clinical implications based on the current knowledge of psychiatric disorders and violence:
Focus on prevention instead of prediction. Predicting future behavior is a population-level activity. However, clinicians are asked to make risk assessments at the individual level, which is difficult, close to impossible. Risk assessment instruments, albeit useful, have, at best, moderate predictive ability (24-27). The task and responsibility of the clinician is to provide adequate preventive measures, including evidence-based health care with continuity and social support. Prevention, not prediction, is the key to violence reduction.
Active identification and adequate treatment of substance use disorders. Previous studies have shown that treating substance use disorders can reduce the risk of criminal recidivism (28-30). Harm reduction is crucial.
Early identification and treatment of first episode psychosis, as well as adequate continued treatment for individuals with psychotic disorders. The treatment option of clozapine should not be neglected as it has anti-aggressive and risk-reducing effects (31, 32).
As several researchers have pointed out, even though associations between some mental disorders and violent or even lethal crime do exist, it is necessary to remember that the vast majority of individuals with psychiatric diagnoses will never carry out any violent acts, much less lethal violence (14, 33). If anything, they are themselves at risk of being victims of crime or unjust actions (34). In-depth knowledge on the matter is imperative to communicate adequate information to patients, their relatives, and the public to prevent stigmatization of individuals with psychiatric disorders. □
References by request:
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