Schizophrenia, substance abuse, and violent crime

Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford OX3 7JX, England.
JAMA The Journal of the American Medical Association (Impact Factor: 35.29). 06/2009; 301(19):2016-23. DOI: 10.1001/jama.2009.675
Source: PubMed


Persons with schizophrenia are thought to be at increased risk of committing violent crime 4 to 6 times the level of general population individuals without this disorder. However, risk estimates vary substantially across studies, and considerable uncertainty exists as to what mediates this elevated risk. Despite this uncertainty, current guidelines recommend that violence risk assessment should be conducted for all patients with schizophrenia.
To determine the risk of violent crime among patients diagnosed as having schizophrenia and the role of substance abuse in mediating this risk.
Longitudinal designs were used to link data from nationwide Swedish registers of hospital admissions and criminal convictions in 1973-2006. Risk of violent crime in patients after diagnosis of schizophrenia (n = 8003) was compared with that among general population controls (n = 80 025). Potential confounders (age, sex, income, and marital and immigrant status) and mediators (substance abuse comorbidity) were measured at baseline. To study familial confounding, we also investigated risk of violence among unaffected siblings (n = 8123) of patients with schizophrenia. Information on treatment was not available.
Violent crime (any criminal conviction for homicide, assault, robbery, arson, any sexual offense, illegal threats, or intimidation).
In patients with schizophrenia, 1054 (13.2%) had at least 1 violent offense compared with 4276 (5.3%) of general population controls (adjusted odds ratio [OR], 2.0; 95% confidence interval [CI], 1.8-2.2). The risk was mostly confined to patients with substance abuse comorbidity (of whom 27.6% committed an offense), yielding an increased risk of violent crime among such patients (adjusted OR, 4.4; 95% CI, 3.9-5.0), whereas the risk increase was small in schizophrenia patients without substance abuse comorbidity (8.5% of whom had at least 1 violent offense; adjusted OR, 1.2; 95% CI, 1.1-1.4; P<.001 for interaction). The risk increase among those with substance abuse comorbidity was significantly less pronounced when unaffected siblings were used as controls (28.3% of those with schizophrenia had a violent offense compared with 17.9% of their unaffected siblings; adjusted OR, 1.8; 95% CI, 1.4-2.4; P<.001 for interaction), suggesting significant familial (genetic or early environmental) confounding of the association between schizophrenia and violence.
Schizophrenia was associated with an increased risk of violent crime in this longitudinal study. This association was attenuated by adjustment for substance abuse, suggesting a mediating effect. The role of risk assessment, management, and treatment in individuals with comorbidity needs further examination.

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Available from: Niklas Långström, Sep 29, 2015
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    • "Indeed, the strongest predictors of violent recidivism for mentally ill offenders are the same as those for non-mentally ill violent offenders, and the presence of a criminal history (including one that antedates the onset of psychosis) is a stronger predictor of violence than psychotic symptoms (Bonta, Law, & Hanson, 1998). However, even when these factors are taken into account, the rate of schizophrenia-associated violence is higher than in the general population (Fazel et al., 2009a, 2009b; Hodgins et al., 2007a; Steadman et al., 1998; Swanson et al., 1990; Volavka, 2013; see above). Much of this increased risk may be due to antisocial personality features and related traits (e.g., impulsivity), as discussed above. "
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    ABSTRACT: Published findings on the relationship between schizophrenia and violence have been mixed, due to differences in study design and quality. In this review, we address the issue with an emphasis on characterizing who is most likely to be violent and when. We conclude that: (1) individuals with schizophrenia are at an increased risk for violence due to specific psychotic symptoms; (2) this risk is increased by brain abnormalities, psychiatric comorbidities, and demographic factors that are not specific to schizophrenia; (3) the majority of violent offenses committed by people with schizophrenia are indistinguishable from offenses committed by others; and (4) despite our knowledge of factors related to increased violence risk and the existence of effective treatments to mitigate this risk, valid risk assessment instruments for this population are lacking, and treatment strategies are rarely employed at any level of psychiatric care. In short, while most people with schizophrenia are not violent and violence committed by people with this condition accounts for only a small percentage of overall violent crime, there is nevertheless a significantly increased risk for violence among subgroups in this population. This has implications for people living with people with schizophrenia, mental health professionals, administrators of psychiatric care facilities, law enforcement personnel, the court system, and policymakers.
    05/2015; 1(1):21-42. DOI:10.1080/23744006.2015.1033154
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    • "[27] [33] [34] [76] "
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    ABSTRACT: Une forte proportion de patients souffrant de schizophrénie, comme l’essentiel des maladies chroniques, a une observance partielle au traitement médicamenteux, potentiellement source de rechute. Les études portant sur cette thématique sont hétérogènes, et une estimation du poids de facteurs clés faisant varier l’observance, et le risque de rechute, n’a pas encore été proposée. Une méta-analyse évaluant le poids de la comorbidité addictive dans l’observance médicamenteuse (et dans le risque de rechute avec hospitalisation) est donc ici proposée.
    L Encéphale 03/2015; 41(2). DOI:10.1016/j.encep.2015.02.002 · 0.70 Impact Factor
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    • "On the other hand, the advantage of the TMC definition is reduced heterogeneity among cases and a more homogeneous sample suited for e.g. biological studies (Fazel et al., 2009; Ripke et al., 2013; Ruderfer et al., 2014; Purcell et al., 2014; Rees et al., 2014; Szatkiewicz et al., 2014). Conversely , the potential disadvantage of the OCO (one case only) definition used in Denmark is a higher risk of false-positive diagnoses. "
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    ABSTRACT: Different case definitions of schizophrenia have been used in register based research. However, no previous study has externally validated two different case definitions of schizophrenia against a wide range of risk factors for schizophrenia. We investigated hazard ratios (HRs) for a wide range of risk factors for ICD-10 DCR schizophrenia using a nationwide Danish sample of 2,772,144 residents born in 1955-1997. We compared one contact only (OCO) (the case definition of schizophrenia used in Danish register based studies) with two or more contacts (TMC) (a case definition of at least 2 inpatient contacts with schizophrenia). During the follow-up, the OCO definition included 15,074 and the TMC 7562 cases; i.e. half as many. The TMC case definition appeared to select for a worse illness course. A wide range of risk factors were uniformly associated with both case definitions and only slightly higher risk estimates were found for the TMC definition. Choosing at least 2 inpatient contacts with schizophrenia (TMC) instead of the currently used case definition would result in almost similar risk estimates for many well-established risk factors. However, this would also introduce selection and include considerably fewer cases and reduce power of e.g. genetic studies based on register-diagnosed cases only. Copyright © 2015 Elsevier B.V. All rights reserved.
    Schizophrenia Research 01/2015; 162(1-3). DOI:10.1016/j.schres.2015.01.018 · 3.92 Impact Factor
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