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Criminal offending and violence

How is criminal offending and violence related to schizophrenia? 

Criminal offending covers a wide range of behaviours from destructive acts, stealing, sexual assaults, to physical assaults causing injury or death. The majority of people with schizophrenia will never commit a crime, however the few who do may help perpetuate a negative public stereotype that schizophrenia is associated with violent behaviour. It is difficult to determine whether any criminal acts committed by people with schizophrenia are a consequence of the illness or are traits of the particular individual. This is confounded by the fact that people with schizophrenia may be at high risk of exposure to the social factors that contribute to criminal offending, such as social disadvantage and substance abuse.

What is the evidence for criminal offending and violence in people with schizophrenia?

Moderate to low quality evidence suggests arrest rates in people with schizophrenia or bipolar disorder are around 40%, which is similar to arrest rates in people with other mental disorders, although the risk of violence is higher in people with personality disorders. Factors associated with a large increased risk of violence in people with schizophrenia are; previous violent victimisation, high verbal aggression, multi-substance misuse, non-adherence to therapies, and previous hospital admissions. Factors associated with a medium-sized increased risk of violence are; homelessness, aggression or hostility, substance misuse, poor impulse control, psychopathy, antisocial personality disorder, a history of conviction, imprisonment, assault, childhood maltreatment, or involuntary hospital admission, and a lack of insight into their disorder. Factors associated with a small increased risk of violence are; parental criminal involvement, parental alcohol misuse, previous suicide attempts, more severe symptoms of schizophrenia, excitement and angry affect, non-white ethnicity, low socio-economic status, non-adherence to antipsychotic medication, and a history of self-destructive behaviour. Moderate quality evidence suggests a small, decreased risk of aggression with better cognitive functioning.

Moderate to high quality evidence suggests the rate of homicide in people with first-episode psychosis is approximately 0.16% prior to treatment and 0.01% after treatment. The rate of any aggression in people during a first episode of psychosis is approximately 31%, and the rate of serious aggression is approximately 16%. Factors associated with violence in people with first-episode psychosis are; involuntary treatment, hostility, having a forensic history, manic symptoms, illegal drug use, being male, being younger, or having a longer duration of untreated psychosis.

Moderate to low quality evidence suggests a small increased risk of repeat offending in people with schizophrenia compared to the general population and compared to people with depression. People with schizophrenia have similar rates of repeat offending as people with substance use disorders, mental retardation or learning disabilities.

Also see the topic on treatments for aggression.


June 2017

Page last updated: 1:01  14 November 2017

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