The role of alcohol and drugs in triggering criminal violence: a case-crossover study*

Individual-level interventions for alcohol-related violence: a rapid evidence assessment

BACKGROUND

Alcohol-related violence is of major concern to society. Around half of all violent crimes are alcohol related, and yet interventions for alcohol-related violence are under-developed. Often, offenders receive treatment for substance use or violence, but not the two in nexus.

AIM

My aim was to conduct a Rapid Evidence Assessment of interventions with a focus on treating established nonsexual violence in the context of alcohol use, to describe the content of these interventions, where they take place and their effectiveness in reducing alcohol problems and/or violence.

METHODS

The electronic databases Embase, Medline, National Criminal Justice Reference Service, Cumulative Index to Nursing and Allied Health Literature were searched together with the Campbell Collaboration; Cochrane Reviews and selected government websites using terms for alcohol, violence and treatment/interventions. The search excluded sexual and intimate partner violence. The focus was on psychosocial interventions with people already in difficulties, not prevention. All empirical study types with people of any age and in any setting (criminal justice, health, social services or education) were included. The principal outcomes of interest were change in alcohol use, violence and alcohol-related violence.

RESULTS

Only four studies of two different interventions were identified. Control of Violence for Angry Impulsive Drinkers has been evaluated with small samples using a nonequivalent comparison group and a single case methodology. Changes were evident on measures of alcohol-related aggression. In a randomised controlled trial, SafERteens participants showed greater improvements in attitudes to alcohol and violence compared with a leaflet only condition.

DISCUSSION

Directions for developing interventions based on alcohol and aggression research are discussed. Interventions targeting primarily alcohol consumption, primarily violence and alcohol-related violence in nexus should be compared. In evaluating these interventions, robust outcome measures should be used across studies to allow comparisons to be made.

CLINICAL IMPLICATIONS

Skills for coping with perceived provocation may be taught, so that nonviolent options are available and so that they become more accessible when people are under the influence of alcohol. Alcohol's effect on reducing self-awareness may be counteracted by teaching mindfulness techniques and the ability to 'act sober' in provocative situations. Setting individual implementation intentions may facilitate harm avoidance in high-risk social situations through preplanning of specific sensible behavioural strategies.

Forensic aspects of drug-induced violence

Violence is unfortunately a part of society. The causes of violence are not completely understood, but it involves sociological, genetic, financial, biological, and environmental factors. Drugs can cause aggression by altering the neurotransmitters dopamine, norepinephrine, gamma-aminobutyric acid (GABA), and serotonin. Specific drugs associated with aggression include alcohol, anabolic steroids, cocaine, amphetamines, sedatives, opiates, and hallucinogens. Aggression can be categorized into impulsive and predatory aggression. Drugs under certain conditions cause impulsive aggression. Sometimes a defense in criminal cases is that the drug caused the violence, that is drug-induced insanity. A case of insanity is more likely to be accepted if the event was unplanned and had no apparent motive. An acceptance of insanity by voluntary intoxication is rarely accepted by the criminal justice system. A more common legal strategy is to seek diminished capacity which aims to obtain a reduction in the severity of the criminal charges. We will discuss some, but not all of the pharmacological and physiological issues relating to drug-induced violence. Then some of the "big picture" forensic issues will be presented. Our goal is to present a primer on the pharmacological and forensic issues relating to drug-induced violence. No attempt was made to provide a comprehensive review of all the literature related to drug-induced violence.

Correlates of serious violent crime for recently released parolees with a history of homelessness

This study used baseline data on recently released paroled men who are homeless (N=157), residing in a residential drug treatment program, and enrolled in a longitudinal study to examine personal, developmental, and social correlates of parolees who are homeless and who have committed serious violent offenses. Having experienced childhood sexual abuse, poor parental relationships, and early-onset incarceration (prior to 21 years of age) were important correlates of serious violent crimes. These findings highlight the need for interventions that address offenders' prior adult and childhood victimization and suggest that policies for reentering violent offenders should encompass an understanding of the broader family contexts in which these patterns of maltreatment often occur.

Understanding early-onset drug and alcohol outcomes among youth: the role of family structure, social factors, and interpersonal perceptions of use

Research on adolescents focuses increasingly on features of the family in predicting and preventing illicit substance use. Multivariate analyses of data from the National Survey of Parents and Youth (N=4173) revealed numerous significant differences on risk variables associated with family structure on adolescent drug-related perceptions and substance use. Youth from dual-parent households were least likely to use drugs and were monitored more closely than single-parent youth (p<0.001). A path analytic model estimated to illuminate linkages among theoretically implicated variables revealed that family income and child's gender (p<0.001), along with family structure (p<0.05), affected parental monitoring, but not parental warmth. Monitoring and warmth, in turn, predicted adolescents' social and interpersonal perceptions of drug use (p<0.001), and both variables anticipated adolescents' actual drug use one year later (p<0.001). Results reconfirm the importance of parental monitoring and warmth and demonstrate the link between these variables, adolescents' social and intrapersonal beliefs, and their use of illicit substances.

Alcohol as a risk factor for sudden infant death syndrome (SIDS)

AIM

To test whether alcohol is a risk factor for sudden infant death syndrome (SIDS).

DESIGN AND SETTING

US epidemiological study using computerized death certificates, linked birth and infant death dataset, and Fatality Analysis Reporting System.

PARTICIPANTS

All SIDS cases (n = 129,090) and other infant deaths (n = 295,151) from 1973-2006; all persons involved in late-night alcohol-related crashes (n = 135,946) from 1994-2008.

MEASUREMENTS

Three measures were used: the expected number of deaths on New Year versus the observed number (expected values were determined using a locally weighted scatterplot smoothing polynomial), the average number of weekend deaths versus the average number of weekday deaths, and the SIDS death rate for children of alcohol-consuming versus non-alcohol-consuming mothers.

FINDINGS

These measures indicate that the largest spikes in alcohol consumption and in SIDS (33%) occur on New Year, alcohol consumption and SIDS increase significantly on weekends, and children of alcohol-consuming mothers are much more likely to die from SIDS than are children of non-alcohol-consuming mothers.

CONCLUSIONS

Alcohol consumption appears to be a risk factor for sudden infant death syndrome, although it is unclear whether alcohol is an independent risk factor, a risk factor only in conjunction with other known risk factors (like co-sleeping), or a proxy for other risk factors associated with occasions when alcohol consumption increases (like smoking). Our findings suggest that caretakers and authorities should be informed that alcohol impairs parental capacity and might be a risk factor for sudden infant death syndrome; in addition, future research should further explore possible connections between sudden infant death syndrome and alcohol.

Does marijuana use lead to aggression and violent behavior?

Marijuana use and violent behavior are causing widespread public concern. This article reviews theory and research on the relation between marijuana use and aggressive/violent behavior. It is evident from the inconsistent findings in the literature that the exact nature of the relation remains unclear. This article identifies several possible reasons for these contradictory findings and provides suggestions for future research. In particular, more research is needed on the different subtypes of aggressive behavior. Further research is also needed to elucidate the associations between gender, marijuana use, and violent behavior. Likewise, an important task for future research is to continue to tease apart the complex relations between gang involvement, marijuana use, and violent behavior. Longitudinal studies also warrant further investigation. Moreover, future research should control for several potentially confounding variables.

Gender differences in re-offending among psychiatrically examined Swedish offenders

BACKGROUND

The gender gap for violent offending is narrowing in the general population. Substance abuse and mental health problems are known risk factors for criminality. While substance abuse treatment has been associated with reduced risk of re-offending, women seem less likely to engage than men. People misusing substances tend to be high users of emergency room (ER) services. Such use may be an indicator both of treatment failure for substance misuse and offending. Little is known about gender differences in this respect.

AIMS

This study aims to test for gender differences in re-offending, use of substance abuse treatment, and hospital ER visits among offenders referred for forensic psychiatric assessment in Sweden.

METHOD

The study used a longitudinal retrospective design. Data on all 31 women from a 2-year (2000-2001) cohort of serious offenders referred for forensic psychiatric assessment in Stockholm county, and 31 men from the same cohort, were extracted from forensic service and national records. Selection of the men was by initial random sampling followed by matching on age and substance misuse. The two resulting samples were compared on health service use and re-offending data between release and the census date (30 April 2004).

RESULTS

There were no gender differences for violent re-offending or for engagement in planned substance abuse treatment, in spite of longer time at risk for the men. Re-offending was reduced for women but not men who did not present in the ER with physical health problems.

CONCLUSIONS

Our study is limited by sample size, although it included all women referred to the specialist forensic psychiatric service over 2 years, but it does indicate that differences between men and women in this situation are likely, and worthy of further study. The only way of achieving adequate sample sizes is likely to be through multi-centre collaboration.

Effects of self-esteem and academic performance on adolescent decision-making: an examination of early sexual intercourse and illegal substance use

PURPOSE

To determine whether higher self-esteem and higher academic performance among youth reduce the likelihood of early sexual intercourse and illegal substance use.

METHODS

Using data from waves I-III of the National Longitudinal Study of Adolescent Health, this study used multivariate logistic regression, stratified by gender and controlling for known covariates, to examine relationships between self-esteem and academic performance and youth decision-making, specifically self-reported initiation of sexual intercourse and use of illegal substances. Self-esteem was constructed as an ascending scale of 10 Likert-scaled survey items. Academic performance was assessed using the most recent grades from English, Math, Science, and History.

RESULTS

Among virginal adolescents, higher self-esteem at baseline had no effect on sexual debut 1 year later. However, higher self-esteem at baseline among females corresponded with a significantly lower likelihood of illegal substance use 1 year later (OR, .96; p = .003). In terms of academic performance at baseline, girls averaging "A" grades as compared with girls averaging "C" grades or lower were significantly less likely to initiate sexual intercourse 1 year later (OR, .52; p = .004). Additionally among girls, being an "A" student or a "B" student was associated with lower odds of illegal substance use, compared with students who averaged "C" grades or lower (p < .01). Among young boys, self-esteem and academic performance were not significantly predictive of illegal substance use.

CONCLUSIONS

This study suggests that bolstering self-esteem and improving academic performance among young girls may have specific benefits in sexual decision-making and substance-related risk-taking.

Design and development of a Telephone-Linked Care (TLC) system to reduce impulsivity among violent forensic outpatients and probationers

Forensic services face the challenge of reducing relapse among clients with a history of violent crime. An automated interactive voice response (IVR) service of the complex Telephone-Linked Care (TLC) type, with a focus on reducing impulsivity, could improve the adequacy of service responses to client needs. Theoretically based in Dialectical Behavior Therapy (DBT), Cognitive Behavior Therapy (CBT) and Motivational Interviewing (MI), the forensic TLC system offers interactive conversations on coping with the emotions of anger, shame and loneliness; activities of daily life such as getting out of bed, asking for help, visiting social services and taking medication; and other areas such as hearing voices, drinking alcohol and self-critical thoughts. We describe the user's flow through the system, with an in-depth synopsis of the hearing voices intervention. Issues regarding voluntary versus mandatory use of the system are addressed in connection with prospective introduction of the system in forensic settings.

The toxicology of homicide offenders and victims: A review

ISSUES

The toxicology of homicide offenders and victims, and homicide as a cause of death among psychoactive substance users.

APPROACH

Review of the toxicology of homicide, and homicide as a cause of death among psychoactive substance users.

KEY FINDINGS

A half or more of offenders are intoxicated by a psychoactive substance at the time of the homicide, with alcohol the most commonly reported substance. Levels of substances among victims are comparable with those seen among perpetrators. Among both offenders and victims, levels of substances far exceed population use. Among substance users, homicide specific mortality rates of substance users far exceed population rates. Reducing rates of alcohol and other drug consumption, at national and individual levels, can be expected to substantially reduce rates of, and risk for, homicide.

CONCLUSIONS AND IMPLICATIONS

Psychoactive substances are strongly associated with homicide. One of the major societal benefits that can be derived from active attempts to reduce alcohol and other drug use are reductions in homicide rates.

Substance Use, Criminal Activity, and Mental Health Among Violent and Nonviolent Rural Probationers

Differences between violent and nonviolent probationers were examined in the growing, yet understudied, rural probation population. Violent rural probationers had higher rates of substance use, criminal activity, and mental health symptoms than did nonviolent rural probationers. Implications for practitioners are discussed.

Suspicion of elder abuse in South Eastern Spain: the extent and risk factors

Elder abuse is recognized internationally as a growing problem. Recent years have seen an increase in the number of authors recommending that the MDs systematically question old people concerning possible abuse. The aim of our study was to ascertain the extent of suspicion of elder abuse and the different types of abuse. We design a cross-sectional survey including 460 patients > or = 65 years at different health centers (South East Spain). A face-to-face interview and a physical examination was carried out. Extent of suspected abuse was 44.6%. Female sex, > or = 75 years, widowhood, living alone or with children, accommodation in house of relatives and income < or = 300 euros/month were the associated sociodemographic variables. The risk factors associated are recent worsening of health, living with a mentally ill person, excessive consumption of alcohol or illegal drugs, arguing frequently with relatives or the dependence on someone to carry out a daily activity. The signs in the physical examination associated are dehydration/malnutrition, pressure ulcers and poor body and/or mouth hygiene. There is a high extent of suspicion of elder abuse and the keyword in this respect is prevention.

Intoxication and violent women

Alcohol and drugs have been linked to severe violent offending among women as well as men. The purpose of this study was to make a contribution to the limited knowledge of characteristics related to the state of intoxication in violent female offenders. The putative differences in the characteristics of female offenders and their violent offenses in relation to the state of intoxication at the time of the violent offending were examined. Of a nation-wide sample of 109 female offenders found guilty of homicide and other violent crimes and incarcerated in 1999-2000 in Finland, 60 offenders participated in the study. Of these offenders 49 (81.7%) had been intoxicated at the time the of index offenses. These were compared with 11 (18.3%) non-intoxicated offenders using a structured interview, the Structured Clinical Interview II for DSM-IV (SCID-II) and the Hare Psychopathy Checklist-Revised (PCL-R). The prevalence of substance abuse or dependence (73.3% and 0%), personality disorder (89.6% and 36.4%), particularly antisocial personality disorder (66.7% and 0%), as well as a history of criminality (69.4% and 0%) were significantly higher among the intoxicated women than among the non-intoxicated. The PCL-R scores were also significantly higher among the intoxicated offenders than among non-intoxicated offenders. The victims of the intoxicated women (23.9%) were less often emotionally close to the perpetrator than were the victims of the non-intoxicated women (66.6%). No differences emerged between the groups in experiences of childhood and adulthood abuse or stressful life events prior to the index crime. The findings indicate that intoxicated violent female offenders exhibit more of the characteristics previously found in violent men, than do the non-intoxicated female offenders. Moreover, the non-intoxicated group comprises both psychotic non-responsible and non-psychotic, fairly well-adjusted women, who are educated, working or studying at the time of the offense and has no history of criminality. Substance misuse constitutes an obvious risk factor for violent behavior in women, and therefore the prevention should include substance abuse treatment.

Family structure and adolescent drug use: an exploration of single-parent families

Data from the 2004 Monitoring the Future survey examined a nationally representative cross-sectional sample of 8th to 12th grade adolescents in rural and urban schools from across the United States (N = 37,507). Results found that drug use among daughters living with single fathers significantly exceeded that of daughters living with single mothers, while gender of parent was not associated with sons' usage. This distinction in adolescent drug use between mother-only versus father-only households is largely overlooked in contemporary studies. Factors responsible for variations in sons' and daughters' usage in single-parent families have important implications for future drug prevention efforts.

Violent offenses associated with co-occurring substance use and mental health problems: evidence from CJDATS

The present study examines the relationship between substance use, mental health problems, and violence in a sample of offenders released from prison and referred to substance abuse treatment programs. Data from 34 sites (n = 1,349) in a federally funded cooperative, the Criminal Justice Drug Abuse Treatment Studies (CJDATS), were analyzed. Among parolees referred to substance abuse treatment, self-reports for the six-month period before the arrest resulting in their incarceration revealed frequent problems with both substance use and mental health. For most offenders with substance use problems, the quantity of alcohol consumed and the frequency of drug use were associated with a greater probability of self-reported violence. Mental health problems were not indicative of increases in violent behavior, with the exception of antisocial personality problems, which were associated with violence. The paper emphasizes the importance of providing substance abuse treatment in relation to violent behavior among offenders with mental health problems being discharged to the community.

Retail sales of alcohol and the risk of being a victim of assault

Russell Bennetts and Rachel Seabrook discuss the implications of a new case-crossover study that links retail alcohol sales and violent assaults.

Alcohol sales and risk of serious assault

BACKGROUND

Alcohol is a contributing cause of unintentional injuries, such as motor vehicle crashes. Prior research on the association between alcohol use and violent injury was limited to survey-based data, and the inclusion of cases from a single trauma centre, without adequate controls. Beyond these limitations was the inability of prior researchers to comprehensively capture most alcohol sales. In Ontario, most alcohol is sold through retail outlets run by the provincial government, and hospitals are financed under a provincial health care system. We assessed the risk of being hospitalized due to assault in association with retail alcohol sales across Ontario.

METHODS AND FINDINGS

We performed a population-based case-crossover analysis of all persons aged 13 years and older hospitalized for assault in Ontario from 1 April 2002 to 1 December 2004. On the day prior to each assault case's hospitalization, the volume of alcohol sold at the store in closest proximity to the victim's home was compared to the volume of alcohol sold at the same store 7 d earlier. Conditional logistic regression analysis was used to determine the associated relative risk (RR) of assault per 1,000 l higher daily sales of alcohol. Of the 3,212 persons admitted to hospital for assault, nearly 25% were between the ages of 13 and 20 y, and 83% were male. A total of 1,150 assaults (36%) involved the use of a sharp or blunt weapon, and 1,532 (48%) arose during an unarmed brawl or fight. For every 1,000 l more of alcohol sold per store per day, the relative risk of being hospitalized for assault was 1.13 (95% confidence interval [CI] 1.02-1.26). The risk was accentuated for males (1.18, 95% CI 1.05-1.33), youth aged 13 to 20 y (1.21, 95% CI 0.99-1.46), and those in urban areas (1.19, 95% CI 1.06-1.35).

CONCLUSIONS

The risk of being a victim of serious assault increases with alcohol sales, especially among young urban men. Akin to reducing the risk of driving while impaired, consideration should be given to novel methods of preventing alcohol-related violence.

Alcohol use among two generations of Southeast Asians in the United States

This article assesses the drinking norms and practices of two generations of Southeast Asians in the East San Francisco Bay Area. Researchers included quantity and frequency measures of current alcohol use and binge drinking and open-ended questions on drinking norms and behaviors in a mixed-method study of tobacco use. The study generated data through in-person interviews with 164 respondents from two urban East Bay neighborhoods. The findings include normative drinking among women and underage youth, with binge drinking among underage youths particularly troubling. Preventive interventions for this population should consider community-level alcohol problems as well as individual alcohol use disorders.

Characteristics of patients who are violent to staff and towards other people from a community mental health service in South East England

Professionals working in the public sector in the UK report widespread violence towards staff working in areas such as health care, social services and education. This study compares the characteristics of patients with and without a history of violence in a large sample of patients attending a community mental health service in South East England. The data were taken from a study of comorbidity and cannabis use in a mental health trust covering a semi-rural population of 250,000 people in Harlow and the surrounding area of South East England. Key workers were interviewed using semi-structured questionnaires from the Comorbidity of Substance Misuse and Mental illness in Community Mental Health and Substance Misuse Services study. Rates of violence against health workers were more than 20 times higher among those patients with a history of violence (23.6% vs. 1%, P<0.001). Alcohol and drug use was more frequent in those who were violent. Prevalence of comorbidity, schizophrenia and personality disorders was high. Key workers' estimates suggested that there was no difference in aggression, engagement or adherence to care plan among those with a history of violence.

Alcohol-induced sleepwalking or confusional arousal as a defense to criminal behavior: a review of scientific evidence, methods and forensic considerations

An increasing number of criminal cases have claimed the defendant to be in a state of sleepwalking or related disorders induced by high quantities of alcohol. Sleepwalkers who commit violent acts, sexual assaults and other criminal acts are thought to be in a state of automatism, lacking conscious awareness and criminal intent. They may be acquitted in criminal trials. On the other hand, criminal acts performed as the result of voluntary alcohol intoxication alone cannot be used as a complete defense. The alcohol-induced sleepwalking criminal defense is most often based on past clinical or legal reports that ingestion of alcohol directly 'triggers' sleepwalking or increased the risk of sleepwalking by increasing the quantity of slow wave sleep (SWS). A review of the sleep medicine literature found no sleep laboratory studies of the effects of alcohol on the sleep of clinically diagnosed sleepwalkers. However, 19 sleep laboratory studies of the effects of alcohol on the sleep of healthy non-drinkers or social drinkers were identified with none reporting a change in SWS as a percentage of total sleep time. However, in six of 19 studies, a modest but statistically significant increase in SWS was found in the first 2-4 h. Among studies of sleep in alcohol abusers and abstinent abusers, the quantity and percentage of SWS was most often reduced and sometimes absent. Claims that direct alcohol provocation tests can assist in the forensic assessment of these cases found no support of any kind in the medical literature with not a single report of testing in normative or patient groups and no reports of validation testing of any sort. There is no direct experimental evidence that alcohol predisposes or triggers sleepwalking or related disorders. A legal defense of sleepwalking resulting from voluntarily ingested alcohol should be consistent with the current state of art sleep science and meet generally accepted requirements for the diagnosis of sleepwalking and other parasomnias.

The effect of rugby match outcome on spectator aggression and intention to drink alcohol

BACKGROUND

Alcohol, aggression and assault injury are strongly associated with popular sporting events, but mediating factors are not clear.

AIMS

To explore aggression, happiness and plans to consume alcohol among spectators before and spectators after sports matches.

METHODS

Cross-sectional surveys of male rugby football fans at an international stadium generated four groups: a pre-match group of 111 men, and three post-match groups of supporters, 17 whose team had won, 23 whose team had lost and 46 whose team had drawn. Consenting participants were assessed using the assault sub-scale of the Buss-Durkee Hostility Inventory, on a self-rating of happiness (Likert scale), for planned alcohol consumption and demographic variables. Pre- and post-match group mean responses were compared.

RESULTS

Analyses were performed on 197 male spectators (mean age 42 years). Spectators in 'win' (z = 2.63, p < 0.01) and 'draw' (z = 2.76, p < 0.01) groups rated themselves as more aggressive than those in the pre-game group, but those in the losing group did not (z = -0.03, p > 0.05). No differences, however, were observed between pre-match, 'win', 'draw' or 'lose' groups on the decision to drink after the match. Winning did not increase happiness (t = 0.25, p > 0.05), but losing (t = 2.09, p < 0.05) or drawing (t = 7.64, p < 0.001) decreased it.

CONCLUSIONS

This study suggests that team success but not failure may increase aggression among supporters, and that aggression, not celebration, drives post-match alcohol consumption. Losing and drawing decreased happiness but winning did not increase it. Better understanding of pathways to violence in these circumstances will pave the way for more effective prevention and management strategies.

Brief report: changes in brain function during acute cannabis intoxication: preliminary findings suggest a mechanism for cannabis-induced violence

BACKGROUND

Recent evidence suggests that cannabis use may be associated with antisocial and violent behaviour, raising the question: What brain mechanisms mediate the disinhibiting effects of cannabis on behaviour?

AIMS/HYPOTHESES

To examine whether an electrocortical measure of affective impulsivity, Go/No Go contingent negative variation, is affected by acute cannabis intoxication.

METHODS

Slow brain potentials were recorded in a Go/No Go noise avoidance task from five habitual cannabis users before, during and after they smoked a cannabis reefer containing 11 mg D-9-tetrahydrocannabinol.

RESULTS

Slow brain potentials developed normally in both Go and No Go conditions before and during cannabis smoking but were severely disrupted 20-40 minutes later, coincident with peak intoxication. Cannabis effects on Go/No Go brain activity resembled those reported to occur in patients with lateral prefrontal cortex lesions.

CONCLUSION/IMPLICATIONS

Our findings are preliminary, calling for larger-scale studies, to confirm the present findings and to investigate whether brain responses to cannabis intoxication differentiate those who are predisposed to suffer adverse consequences of cannabis use from those who are not.

Short-term effects of psychiatric symptoms and interpersonal stressors on criminal violence--a case-crossover study

BACKGROUND

The aim of the study was to analyse the triggering or acute risk effect of psychiatric symptoms and interpersonal stressors on criminal violence.

METHOD

One hundred and thirty three violent offenders were recruited from a forensic psychiatric evaluation (FPE) unit and a national prison evaluation unit in Sweden during 2002-2003, and were interviewed about trigger exposures. A case-crossover design was used eliminating long-term within individual confounding.

RESULTS

Suicidal ideation or parasuicide within 24 h before the violent event conferred a ninefold risk increase. In contrast, violent ideation did not trigger criminal violence. Hallucinations yielded a fourfold risk increase, whereas paranoid thoughts were associated with a small and statistically non-significant risk increase. Acute conflicts with others and being denied psychiatric care within 24 h before violence also increased the risk of acting violently.

CONCLUSIONS

Some tested psychiatric symptoms and stressors triggered criminal violence, whereas others did not. The case-crossover design may be particularly useful for the study of triggers of violence.