Violence in psychosis: conceptualizing its causal relationship with risk factors

Background: While statistically robust, the association between psychosis and violence remains causally unexplained. Objective: To provide an overview of possible causal pathways between risk factors and violence in psychosis. Methods: A structured narrative review of relevant studies published between 1990 and 2013, found via online databases and bibliographies. Both reviews and empirical studies were included. No restrictions were applied to language, study design, sample characteristics and measurement of psychosis and violence. Case reports and studies about self-harm were excluded. A final sample of 69 studies was used. Findings: The lack of knowledge regarding the causal relationship between psychosis and violence is partially due to methodological aspects of research. These aspects include study design, sampling, operationalization and confounding variables. Moreover, violence is the potential outcome of several interrelated risk factors: demographics, social factors, persecutory delusions, command hallucinations, comorbid antisocial personality pathology, substance use, inadequate insight, treatment non-adherence and physiological factors. Forty-one possible causal pathways between these risk factors and violence are presented. Conclusions: This study stimulates research by providing a theoretical framework, avenues for future investigation and methodological recommendations. Understanding violence in psychosis enhances its prevention and treatment, decreases stigma associated with psychosis and improves the patient’s legal position

Cognition and violent behavior in psychotic disorders: a nationwide case-control study

Background: The excess risk of violence in psychotic disorders may partly be explained by impairments in executive functions (EFs) and theory of mind (ToM). However, previous studies have been limited by composite measures of EFs and small samples of inpatients. Methods: Data were collected for the research project Genetic Risk and Outcome of Psychosis (GROUP). Patients with psychotic disorders (N=891) were recruited from various care settings in the Netherlands. The following neuropsychological tests were administered (targeted cognitive function in parentheses): (i) Continuous Performance Test-HQ (inhibition); (ii) Response Shifting Task (cognitive flexibility); (iii) Wechsler Adult Intelligence Scale, Third Edition (WAIS-III) Block Design subtest (fluid intelligence); (iv) Neuropsychological Assessment Battery (NAB) Mazes Test (planning); (v) Degraded Facial Affect Recognition Task (affective ToM); and (vi) Hinting Task (cognitive ToM). Lifetime violence was ascertained from medical records and patient interviews. We used analysis of covariance to compare the mean scores of violent and nonviolent patients on each test, adjusting for age and sex. Results: Violent patients performed significantly worse than nonviolent patients on the WAIS-III Block Design subtest (F [1, 847]=5.12, p=.024), NAB Mazes Test (F [1, 499]=5.32, p=.022) and Hinting Task (F [1, 839]=9.38, p=.002). For the other tests, the between-group differences were nonsignificant. Violent behavior explained no more than 1% of the variance in performance on each test. Conclusion: Impairments in EFs and ToM are unlikely to provide useful targets for risk assessment and interventions

Structural brain correlates of interpersonal violence: systematic review and voxel-based meta-analysis of neuroimaging studies

Owing to inconsistent nomenclature and results, we have undertaken a label-based review and anatomical likelihood estimation (ALE) meta-analysis of studies measuring the quantitative association between regional grey matter (GM) volume and interpersonal violence. Following PRISMA guidelines, we identified studies by searching 3 online databases (Embase, Medline, PsycInfo) and reference lists. Thirty-five studies were included in the label-based review, providing information for 1288 participants and 86 brain regions. Per region, 0–57% of the results indicated significant reductions in GM volume, while 0–23% indicated significant increases. The only region for which more than half of all results indicated significant reductions was the parietal lobe. However, these results were dispersed across subregions. The ALE meta-analysis, which included 6 whole-brain voxel-based morphometry studies totaling 278 participants and reporting 144 foci, showed no significant clusters of reduced GM volume. No material differences were observed when excluding experiments using reactive violence as outcome or subjects diagnosed with psychopathy. Possible explanations for these findings are phenomenological and etiological heterogeneity, and insufficient power in the label-based review and ALE metaanalysis to detect small effects. We recommend that future studies distinguish between subtypes of interpersonal violence, and investigate mediation by underlying emotional and cognitive processes

Use of illicit substances and violent behaviour in psychotic disorders: two nationwide case-control studies and meta-analyses

Background. Substance use disorder explains much of the excess risk of violent behaviour in psychotic disorders. However, it is unclear to what extent the pharmacological properties and subthreshold use of illicit substances are associated with violence. Methods. Individuals with psychotic disorders were recruited for two nationwide projects: GROUP (N = 871) in the Netherlands and NEDEN (N = 921) in the United Kingdom. Substance use and violent behaviour were assessed with standardized instruments and multiple sources of information. First, we used logistic regression models to estimate the associations of daily and nondaily use with violence for cannabis, stimulants, depressants and hallucinogens in the GROUP and NEDEN samples separately. Adjustments were made for age, sex and educational level. We then combined the results in random-effects meta-analyses. Results. Daily use, compared with nondaily or no use, and nondaily use, compared with no use, increased the pooled odds of violence in people with psychotic disorders for all substance categories. The increases were significant for daily use of cannabis [pooled odds ratio (pOR) 1.6, 95% confidence interval (CI) 1.2–2.0), stimulants (pOR 2.8, 95% CI 1.7–4.5) and depressants (pOR 2.2, 95% CI 1.1–4.5), and nondaily use of stimulants (pOR 1.6, 95% CI 1.2–2.0) and hallucinogens (pOR 1.5, 95% CI 1.1–2.1). Daily use of hallucinogens, which could only be analysed in the NEDEN sample, significantly increased the risk of violence (adjusted odds ratio 3.3, 95% CI 1.2–9.3). Conclusions. Strategies to prevent violent behaviour in psychotic disorders should target any substance use

Validation and recalibration of OxMIV in predicting violent behaviour in patients with schizophrenia spectrum disorders

Oxford Mental Illness and Violence (OxMIV) addresses the need in mental health services for a scalable, transparent and valid tool to predict violent behaviour in patients with severe mental illness. However, external validations are lacking. Therefore, we have used a Dutch sample of general psychiatric patients with schizophrenia spectrum disorders (N = 637) to evaluate the performance of OxMIV in predicting interpersonal violence over 3 years. The predictors and outcome were measured with standardized instruments and multiple sources of information. Patients were mostly male (n = 493, 77%) and, on average, 27 (SD = 7) years old. The outcome rate was 9% (n = 59). Discrimination, as measured by the area under the curve, was moderate at 0.67 (95% confidence interval 0.61–0.73). Calibration-in-the-large was adequate, with a ratio between predicted and observed events of 1.2 and a Brier score of 0.09. At the individual level, risks were systematically underestimated in the original model, which was remedied by recalibrating the intercept and slope of the model. Probability scores generated by the recalibrated model can be used as an adjunct to clinical decision-making in Dutch mental health services

Preventing crime in cooperation with the mental health care profession

Although major mental disorders do not have a central position in many criminological theories, there seems to be an evident relationship between these disorders and criminal behavior. In daily practice police officers and mental health care workers work jointly to prevent nuisance and crime and to keep the city livable. Examining the situations where the criminal justice system and mental health institutes are jointly involved to prevent crime, some pitfalls emerge that seem to threaten successful cooperation. There appear to be unrealistic expectations of the possibility to reduce the risk of reoffending by means of treatment and of the possibility to predict which offender poses a risk to society. Another complexity is the fact that both parties work from different backgrounds and pursue different goals. The way society and the criminal justice system deal with persons who are assumed to be a risk to the community because of a mental disorder demands a further investigation from a criminological perspective

Risk factors for violent behaviour in psychotic disorders: substance use and cognition

Background People with psychotic disorders are at increased risk of violent behaviour. One of the most robust risk factors is problematic substance use. However, the effects of pharmacologically different categories of illicit substances (e.g. stimulants, hallucinogens) and nonproblematic use on violence risk remain unclear. Impairments in executive functions and mentalizing abilities – a key feature of psychotic disorders – are hypothesized to underly violent behaviour. However, the few studies investigating this hypothesis have produced conflicting results and used composite measures of executive functions. Additionally, previous studies have been limited by reliance on selective samples of male inpatients or prisoners and criminal records for the measurement of violence. Methods Data came from Genetic Risk and Outcome of Psychosis, a multi-centre project in the Netherlands. Patients with psychotic disorders (N = 891) were recruited at various care settings (e.g. psychiatric hospitals, outpatient clinics) in geographically representative areas of the country. Problematic and nonproblematic use of alcohol, cannabis, stimulants, depressants and hallucinogens at any point in life were ascertained using the Composite International Diagnostic Interview-Substance Abuse Module. Neuropsychological tests were used to measure inhibition (Continuous Performance Test-HQ), cognitive flexibility (Response Shifting Task), fluid intelligence (Wechsler Adult Intelligence Scale-Third Edition [WAIS-III] Block Design subtest), planning (Neuropsychological Assessment Battery Mazes Test) and cognitive (Hinting Task) and affective (Degraded Facial Affect Recognition Task) mentalization. Lifetime violent behaviour was recorded with the Life Chart Schedule based on patient and parent interviews and case notes. In two studies, I investigated the associations of violence with: (i) problematic and nonproblematic use of each substance category using logistic regression; and (ii) performance on each neuropsychological test using analysis of covariance. All analyses were adjusted for age and gender. Results Problematic and nonproblematic use increased the odds of violent behaviour between 20% and 100% across substance categories. The increases were significant for problematic use of alcohol (adjusted odds ratio [aOR] 1.7, 95% confidence interval [CI] [1.0, 1.3]), stimulants (aOR 2.0, 95% CI [1.3, 3.0]) and depressants (aOR 2.0, 95% CI [1.0, 3.9]), and nonproblematic use of hallucinogens (aOR 2.0, 95% CI [1.3, 3.1]). Violence accounted for 1% or less of the variance in performance across neuropsychological tests. Violent patients performed significantly worse than non-violent patients on the WAIS-III Block Design subtest (F [1, 847] = 5.1, p = .024) and Hinting Task (F [1, 839] = 9.4, p = .002). Conclusions Problematic and nonproblematic use of all substance categories increase violence risk, which needs consideration in risk assessment and prevention. The small effect sizes suggest that deficits in fluid intelligence and cognitive mentalizing ability mainly have theoretical relevance. Future studies may improve our understanding of causal mechanisms with prospective designs and tests of additional possible confounders (e.g. genetics, childhood maltreatment) and mediators (e.g. treatment nonadherence, unemployment).</p

Use of illicit substances and violent behaviour in psychotic disorders: two nationwide case-control studies and meta-analyses.

Background: Substance use disorder explains much of the excess risk of violent behaviour in psychotic disorders. However, it is unclear to what extent the pharmacological properties and subthreshold use of illicit substances are associated with violence.Methods: Individuals with psychotic disorders were recruited for two nationwide projects: GROUP (N = 871) in the Netherlands and NEDEN (N = 921) in the United Kingdom. Substance use and violent behaviour were assessed with standardized instruments and multiple sources of information. First, we used logistic regression models to estimate the associations of daily and nondaily use with violence for cannabis, stimulants, depressants and hallucinogens in the GROUP and NEDEN samples separately. Adjustments were made for age, sex and educational level. We then combined the results in random-effects meta-analyses.Results: Daily use, compared with nondaily or no use, and nondaily use, compared with no use, increased the pooled odds of violence in people with psychotic disorders for all substance categories. The increases were significant for daily use of cannabis [pooled odds ratio (pOR) 1.6, 95% confidence interval (CI) 1.2–2.0), stimulants (pOR 2.8, 95% CI 1.7–4.5) and depressants (pOR 2.2, 95% CI 1.1–4.5), and nondaily use of stimulants (pOR 1.6, 95% CI 1.2–2.0) and hallucinogens (pOR 1.5, 95% CI 1.1–2.1). Daily use of hallucinogens, which could only be analysed in the NEDEN sample, significantly increased the risk of violence (adjusted odds ratio 3.3, 95% CI 1.2–9.3).Conclusions: Strategies to prevent violent behaviour in psychotic disorders should target any substance use

Validation and recalibration of OxMIV in predicting violent behaviour in patients with schizophrenia spectrum disorders

Oxford Mental Illness and Violence (OxMIV) addresses the need in mental health services for a scalable, transparent and valid tool to predict violent behaviour in patients with severe mental illness. However, external validations are lacking. Therefore, we have used a Dutch sample of general psychiatric patients with schizophrenia spectrum disorders (N = 637) to evaluate the performance of OxMIV in predicting interpersonal violence over 3 years. The predictors and outcome were measured with standardized instruments and multiple sources of information. Patients were mostly male (n = 493, 77%) and, on average, 27 (SD = 7) years old. The outcome rate was 9% (n = 59). Discrimination, as measured by the area under the curve, was moderate at 0.67 (95% confidence interval 0.61–0.73). Calibration-in-the-large was adequate, with a ratio between predicted and observed events of 1.2 and a Brier score of 0.09. At the individual level, risks were systematically underestimated in the original model, which was remedied by recalibrating the intercept and slope of the model. Probability scores generated by the recalibrated model can be used as an adjunct to clinical decision-making in Dutch mental health services