IN REVIEW


Mental Illness and Violence: An Epidemiological Appraisal of the Evidence

J Arboleda-Flórez MD, FRCPC, FAPA, DABFP, PhD1


Objective: To conduct a critical review of the literature on the matter of mental illness and violence, to examine whether there is enough evidence to establish a causal link, and to provide epidemiological background to measure the risk to the population.

Method: Based on a computerized search of the literature on mental illness and violence previously conducted for Health Canada, studies in the area were critically reviewed and divided into 3 main categories: 1) studies of criminal and violent behaviour among psychiatric patients, 2) studies of psychiatric illness among offenders (prevalence studies in institutions, analytical studies, and community follow-up of offenders), and 3) epidemiological community-based studies on the issue of mental illness and violence (police–citizen encounters, representative samples, and other epidemiological studies). Causality rules and measures of risk were then applied to the evidence elicited.

Results: The review of the literature suggests that only a small minority of hospitalized patients, typically those suffering from acute psychotic symptoms, are involved in violent incidents. Formerly hospitalized patients are at a higher risk of committing violence if they are not properly treated and are experiencing threat/control-override psychotic symptoms. Substance abuse disorders significantly raise the risk for violence. Family members are the most at risk of being victimized.

Conclusion: An association exists between mental illness and violence, but the many covariations that naturally affect the equation between them introduce uncertainties in establishing causality.  

(Can J Psychiatry 1998;43:989–996)

Key Words: deinstitutionalization, violence, criminalization, offenders, causality

Advocates for mentally ill persons have traditionally stated that persons with mental illness are no more likely to commit violent acts than are persons who are not mentally ill. This long-sustained position has become harder to hold in light of sensational media coverage of crimes committed by mentally ill persons (1), television dramas that depict mentally ill persons as dangerous (2,3), and scientific reports that point toward an association between mental illness and violence (4–6). That an association exists seems to be an accepted fact, but the exact nature of the association remains to be determined. This complex issue and its final resolution have important consequences for persons who suffer from mental disorders and their families, health care providers, legislators, programmers, and personnel in the justice and criminal systems (7).

Objective and systematic study of the relationship between mental illness, violence, and dangerousness is crucial to the formulation of appropriate and effective policies for the provision of mental health services (8). This proposition-like statement holds true regardless of whether the service is required in the community, the mental health system, or correctional settings. Evidence supporting a relationship between mental illness and violence is also pivotal in the debate concerning the appropriate use of involuntary hospitalization, in the design of community-based controls for violence among persons with mental illness (9), and in the utilitarian need to understand the social consequences of deinstitutionalization (10).

In the postdeinstitutionalization era, negative community attitudes and fears have been cited as the most persistent obstacle to the fulfilment of community-based treatment goals (11,12). In Canada, these attitudes and fears may also obstruct health restructuring initiatives that are placing unprecedented pressures on psychiatric facilities to transfer persons with mental illness to the community, to curtail lengths of stay, and to reduce access to psychiatric beds.

While the claim that mentally ill persons are violent traditionally has been opposed by mental health advocates and researchers (13), recent literature reviews and research reports suggest that mental illness may be causally connected to violence, particularly for certain subgroups of the mentally ill population (14,15). As we confront a major second wave of dehospitalization and renewed scientific controversy, it is indeed very pertinent 1) to review the literature on mental illness and violence, 2) to question whether compelling scientific evidence already exists to support a causal understanding of the relationship between them, and 3) to assess the potential risk that mental patients could pose to the community.

This paper, therefore, presents a review of the literature on mental illness and violence and undertakes a critical epidemiological appraisal of the evidence in regard to causality and potential risk.

Literature Review

Studies that have examined the relationship between mental illness and violence have focused on the violent behaviour of identified psychiatric patients or on the presence of mental illness among identified offenders. With some overlap, these studies could be divided into 3 large categories: 1) studies of psychiatric patients, 2) studies of offenders, and 3) epidemiological community-based studies.

Studies of Psychiatric Patients

About 20% of studies (7) on mental illness and violence have focused on physical violence of hospitalized psychiatric patients. Most of these studies have concluded that a small percentage of patients (about 5%) are responsible for just over one-half of all violent incidents and for more than one-half of the serious injuries (16,17). Patients with psychotic symptoms, particularly paranoid symptoms, have been found to be at a higher risk for physical aggression toward others (18–20), and among psychogeriatric patients, those suffering from dementia have been shown to present a greater risk of violence (21). Noble and Rodger report an increase of violent incidents occurring in hospitals between 1976 and 1984 (18). Similarly, Volavka and others report an increasing trend in the prevalence of arrests of psychiatric patients for incidents that occurred while in hospital (22).

In a study in a university-based, locked, short-term psychiatric inpatient unit, Straznickas and others found that 19% of patients (113 of 581) had physically attacked someone in the 2 weeks prior to their admission (23). Among those who had assaulted someone, 50 had assaulted people outside of the family, 10 had assaulted both family members and individuals outside of the family, and 53 had assaulted only family members. In addition, 31 of those patients who were assaultive had attacked more than 1 person.

Violence and fear-inducing behaviour have been found to be characteristic of the acute exacerbations of chronic conditions such as schizophrenia or mania leading to hospitalization. For example, Binder and others found that 21% of randomly selected inpatients (N = 150) in a university psychiatric unit had attacked persons and that 25% had engaged in fear-inducing behaviour in the 2 weeks prior to their admission (24). This was especially true for patients suffering from schizophrenia or mania. In addition, 13% of patients attacked others during their admission, and 32% engaged in fear-inducing behaviour. Patients with a diagnosis of mania were more likely to attack others, while those with a diagnosis of schizophrenia were more likely to engage in fear-inducing behaviour.

Many studies have examined the relationship of specific symptoms and diagnoses to violence. Link and Stueve compared a sample of 232 patients, 42 of whom were inpatients, with a community representative sample of 521 individuals chosen from the same neighbourhood as the patients (25). Current and former patients were significantly more likely to have engaged in hitting, fighting, and weapon use than never-treated community controls, and this association remained when groups of patients were divided into more detailed treatment groups (first-contact, repeat-contact, former patients). Patients who were suffering from threat/control-override psychotic symptoms were more likely to engage in violent behaviours. This finding was associated with a strong dose response, so those patients at the high end of the scale were more prone to violent acts than those at the lower end. The authors concluded that the threat/control-override symptom scale largely explained the association between patient status and violence.

Perhaps the most consistent and striking findings are the association of substance abuse disorders (alcohol and/or drug abuse) to violence and criminality and the small association or lack of association of other disorders (for example, schizophrenia, affective disorders, anxiety disorders) to violence (26). The relationship of substance abuse disorders and violence was indicated as early as 1974 (27). Guze and others demonstrated that patients with diagnoses of sociopathic personality disorder and substance abuse were more likely to have a history of felony convictions. This finding led the authors to conclude that sociopathy, alcoholism, and drug dependence were the principal psychiatric disorders associated with crime. Similar findings have been reported in more recent studies (28,29).

The importance of substance abuse as a predictor of violence was found to hold, even when studies were restricted to a single diagnostic group, such as patients with schizophrenia. Cuffel and others, for example, studied only patients who had been diagnosed with schizophrenia to determine whether a comorbid substance abuse diagnosis increased the risk of subsequent violence (30). Data were gathered from a retrospective review of files of 103 outpatients. Violent behaviour was broadly defined from verbal threats to destruction of property and physical assaults. Patients who were polysubstance abusers were found to be significantly more likely to commit a violent act.

Another significant finding from this body of research points to the importance of prior violence and criminality in predicting subsequent violence and criminality (31–34). This relationship is important because of the high percentage of mentally ill patients who report prior criminal and violent acts (29,35). Cirincione and others, after controlling for the effects of arrest history, assessed the extent to which a diagnosis of schizophrenia was predictive of criminal violence among 2 cohorts of patients admitted to a New York State facility, one in 1968 (N = 255) and the other in 1978 (N = 327) (36). Data were obtained for violent crimes (murder, manslaughter, rape, attempted rape, kidnapping, and sodomy) for 11 years following the index admission. Prior arrest history significantly correlated with violent crime in both cohorts. For those without prior arrest, diagnosis did not predict subsequent violent crime. Similarly, Wessely and others demonstrated a slightly increased risk of criminality among those patients with schizophrenia (37). However, the much larger effects of prior criminality and substance abuse overshadowed this increase.

Finally, the study by Buckley and others draws attention to and provides information on the likely target of violence (38). These authors studied 698 patients who were diagnosed with schizophrenia and admitted to a psychiatric inpatient department between 1983 and 1988. Patients with a history of violence were found to be similar to those without such history with respect to positive or negative symptomatology or family history of mental illness. Sixteen percent of these patients, mostly males, had engaged in a physically violent or destructive (to property) act since the onset of their illness. Most of the incidents of community violence occurred in the home and involved episodes of damage to furniture or assaults on relatives.

Studies of Offenders

Studies of mental illness among offender populations include those that have estimated the prevalence of mental conditions in incarceration settings, analytical studies of mental disorder and violence, and follow-up of offenders released to the community.

Prevalence Studies in Institutions. Two Canadian studies provide compelling evidence that a significant proportion of incarcerated persons suffer from substance abuse disorders and serious mental illness. In a study at the Remand Centre in Edmonton, Bland and others, on a sample of 180 inmates, found a lifetime prevalence of any psychiatric disorder of 92% and, in descending order, substance abuse 87%, antisocial personality disorder 57%, affective disorder 23%, and schizophrenia 2% (39). This systematic sample was obtained from males in custody at the Remand Centre in Edmonton who were examined by lay interviewers using the Diagnostic Interview Schedule (DIS). The larger than usual proportion of antisocial personality disorders found in this study may have been a function of the DIS, which uses information about criminality in the diagnostic criteria.

In a more recent and larger study, Arboleda-Flórez took a stratified simple random sample of 1200 admissions to the Calgary Remand Centre (40). Subjects were examined within the first 24 hours of detention by 4 senior forensic psychiatrists who used the Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders (DSM) (SCID), the Hare Psychopathy Checklist (PCL), the General Health Questionnaire (GHQ), and other instruments. A principal diagnosis on either Axis I or Axis II of the DSM-III-R was made in 728 of the 1200 interviewees (60.7%). The 1-month prevalence was 49.5% for females and 56% for males for an Axis I disorder and 3.6% for females and 5.5% for males for an Axis II personality disorder. Substance abuse disorder occurred in 35.7% of women and 47.3% of men. Schizophrenia was not found among women (possibly because there were fewer women in the sample) but occurred in 1.2% of males.

Studies showing a high prevalence of substance abusers among incarcerated offenders also have been reported in the United States (41,42) and the United Kingdom (43).

Analytical Studies Among Offenders. Very many studies have examined whether violent criminality can be associated with mental illness or a particular diagnosis within offender populations. Since most of these studies have suffered from multiple methodological problems and have yielded inconsistent results, only the most recent and important ones are reviewed here. Toch and Adams’ study is the largest (44). These authors used record linkage technology to study the relationship between mental illness and criminality in New York State. Computer records of 8379 inmates were matched to New York State Mental Health services records. Inmates were considered to have suffered from a mental illness if they appeared in the mental health files. Of those without a history of mental illness, 13.8% had a history of recent or remote violence compared with 17% of those with a history of mental illness or substance abuse. In addition, 5.8% of those with a combination of mental illness and substance abuse committed unmotivated violent acts compared with only 1.2% of those without a history of either.

Rice and Harris studied violent recidivism among matched cohorts of 685 persons referred for a brief forensic psychiatric assessment (45). Psychopathy, schizophrenia, and alcohol abuse were the independent variables. Violent recidivism occurred in 31% of the subjects. A diagnosis of alcohol abuse alone or in combination with psychopathy (diagnosed with the PCL) was more frequently related to violent recidivism. Persons diagnosed with schizophrenia were less likely to recidivate.

Abram conducted a study aimed at unravelling interactions among alcoholism, drug abuse, and antisocial personality disorder (46). The study found a relationship between antisocial personality disorder and 3 levels of prior criminality (violent crime, felony property crime, and “other” crime [misdemeanours]) and a relationship between substance abuse disorders and 2 levels of prior criminality (felony property crime and “others”). Intriguingly, this study did not find an association between alcoholism or “drug disorders” and criminality, even when controlled for age and comorbid disorders, usually antisocial personality disorders. This finding echoes the statement made by Monahan and Steadman that “no relation or, at best, a much weaker relation is found” between crime and mental disorder when controlling for demographic and life-history factors (13).

Finally, a Canadian study by Hodgins and Côté examined the relationship of mental disorder to violent criminality in a representative sample of 461 inmates at a penitentiary in Quebec (47). A total of 107 individuals were defined as mentally disordered based on DIS diagnoses. These individuals were not found to have a history of more convictions or more violent convictions compared with offenders who were not mentally ill.

Community Follow-Up Studies of Offenders. The relationship between mental illness and subsequent community adjustment among released offenders has received scrutiny in several studies.

In Chicago, Abram and Teplin were specifically interested in whether persons with dual diagnoses (mental illness and substance abuse) committed more violent crimes than those who were not mentally ill but had a history of drug abuse (48). A random sample of 728 released offenders was followed for 3 years. Measures of mental illness and substance abuse were collected using the DIS, and arrest data were obtained from the Chicago Police Department, the Illinois Bureau of Investigations, and the Federal Bureau of Investigation. Previous arrests for violent crime and time at risk (number of days out of jail) were positively associated with subsequent commission of violent crime. An opiate disorder diminished the probability of future arrest for violent crime, but the authors point out that their data were collected prior to the crack-cocaine epidemic in the United States. Mental disorders (schizophrenia, depression, alcohol abuse) did not predict subsequent arrest for a violent crime after controlling for age or education.

In a 6-year follow-up of this cohort, the authors studied whether postrelease arrest rates for violent crime for these same offenders were related to mental disorder (49). Findings indicated that those persons with schizophrenia or major affective disorders and with substance abuse had a probability of 0.43 and 0.46, respectively, for rearrest. In every diagnostic group, those with a history of violent crime were twice as likely to be rearrested during the follow-up period compared with those with no history. Although persons with a history of hallucinations and delusions did not have a higher probability of subsequent arrest, they did have a slightly higher number of arrests for violent crimes.

Similar results were reported by Feder, who compared the postprison adjustment of mentally ill offenders (N = 147) with a group of offenders who were not mentally ill (N = 400) over a period of 18 months (50). No differences were noted between the groups when controlling for criminal history. Sixty-four percent of mentally ill offenders and 60% of not ill offenders were rearrested at least once during the follow-up; 19% of the mentally ill offenders and 15% of the not ill offenders were rearrested for violent crime.

Epidemiological Community Studies

Police–Citizen Encounters. Because of the considerable discretionary powers of police, the argument has been made that the rate of arrest of mental patients in a community is related to deinstitutionalization factors and the availability of alternatives to incarceration (51,52). In this regard, Teplin observed a random sample of 283 police officers in their day-to-day interactions with the public (53). A symptom checklist was used to assess the presence and severity of psychiatric impairment among those coming into contact with the police. She found that police encounters with individuals with a mental disorder occurred infrequently (4% of 2122 person-encounters). Further, she observed that persons with mental disorders were only slightly more likely than those without a disorder to be considered suspects in crime; for those who were considered suspects, the type of crime was not found to be related to the presence or absence of mental disorder. The pattern of crime among mentally ill suspects was substantially similar to the pattern among suspects who were not mentally ill.

Two studies by Holley and Arboleda-Flórez reported similar findings regarding police–citizen encounters in Calgary (54,55). These studies involved 350 persons who came into contact with the police over a 2-week period. Police officers were asked to rate observable behaviour of these individuals in a continuum from normal to severely abnormal. They were then asked to judge the cause of the abnormal behaviour: alcohol, drugs, mental illness, or other. The authors found no significant differences in the number or type of crimes among those rated mentally ill and those assessed to be not mentally ill.

Representative Samples. Several studies have been conducted on representative samples in the community. Three have used Epidemiological Catchment Areas (ECA) methodology, characterized by large, representative samples and the administration of the DIS by lay interviewers. Swanson and others made use of data from 3 of the 5 sites in the original ECA studies (4). In a sample of 10 059 subjects, the authors found that more than one-half of the individuals who reported violent behaviour in the preceding year met the criteria for a psychiatric disorder compared with only 19.6% among the nonviolent respondents. Later, Swanson, using the same ECA data, further tested the hypothesis that the relationship between mental disorder and violence could be largely explained by the association between alcohol abuse and violence (56). He found that mental illnesses uncomplicated by alcohol abuse were associated with some increased risk of violence but that the large increase in violence among younger males of low socioeconomic status was largely due to the increased prevalence of alcohol abuse and comorbidity in this group.

In Edmonton, Bland and Orn used the ECA methodology to study 3 diagnostic categories among 1200 subjects: antisocial personality disorders, major depression, and alcohol abuse–drug dependence (5). Altogether, 54.5% of those with a diagnosis were involved in violent behaviour compared with 15.5% of those without a diagnosis. Persons with 1 or more of these diagnoses were almost 7 times more likely to be involved with violence than those without any of these disorders, and the risk of violence was higher among those with a comorbid alcohol abuse disorder. Of concern, it was noted that when alcohol was combined with antisocial personality and/or depression, 80% to 93% of these individuals were involved in violence. Both these studies suggest that the risk of assaultiveness is greater among those who abuse substances than in those suffering from a major mental illness such as schizophrenia, affective disorders, or anxiety disorders.

Other Epidemiological Studies. The study by Link and Stueve, previously discussed, had an advanced methodology: the use of community controls and the identification of several levels of severity in the measurements (25).

A large record-linkage study in Sweden conducted by Hodgins identified a birth cohort of 15 117 persons born in 1953 and still residing in Sweden in 1983 (57). This retrospective historical cohort was followed up for 30 years to determine the proportion of those who had required a psychiatric admission (N = 603). This group was then compared on criminal variables with those in the cohort who had never experienced any admissions to a psychiatric ward or to an institution for the mentally deficient. The results indicate that, compared with the “normal” controls, men with major disorders were 4.16 times (95% CI, 2.23–7.78) more likely and women were 27.45 times (95% CI, 9.80–76.88) more likely to have been convicted of a violence offense.

By far, the most up to date and methodologically sound epidemiological study of mental illness and violence is that by Steadman and others (58). This study monitored violence to others at 10-week intervals for 1 year after discharge among 1136 mentally disordered male and female patients aged 18–40 years. Patient self-reports were augmented by reports from collateral informants and by police and hospital records. Members of a comparison group, consisting of 519 people living in the same neighbourhoods as the patients, were also interviewed for violent behaviour once every 10 weeks. The prevalence of violence among patients was not significantly different from that among members of the control group who had no symptoms of substance abuse. Substance abuse symptoms significantly raised the rate of violence in both the patient and the comparison groups, but a higher proportion of patients reported symptoms of substance abuse. Violence in both patient and comparison groups was most frequently targeted at family members and friends and usually occurred at home. The authors concluded that the prevalence of community violence by people discharged from acute psychiatric facilities varies considerably according to diagnosis and, particularly, cooccurring substance abuse diagnosis or symptoms.

On the Matter of Cause

Monahan and Steadman in 1983 pointed out that, when appropriate statistical controls were applied to factors such as age, race, social class, and previous institutionalization, relations between crime and mental disorder tended to disappear (13). For a decade, this statement served as the touchstone by which mental health providers and scientists alike understood the relationship between mental illness and violence. Monahan changed this in 1993 when he stated that, in his opinion, this conclusion may have been premature, and may well be wrong (14). He reasoned that controlling for factors such as social class and institutionalization might be wrong because these are highly related to mental disorder, and the control would attenuate the relationship between mental illness and violence.

Monahan’s reversal deals with core statistical models, which must be properly designed and executed for studies to yield data of analyzable quality. Unfortunately, most studies mentioned above suffer from serious methodological flaws at the design stage, so even if the data are of good quality, results may not be properly applicable to a finding of causality. These flaws include failure to control for confounding factors, selection and misclassification biases, and failure to appreciate the limitations of the lack of temporal ordering of factors. In addition, the studies fail to pay attention to a factor of confounding by definition, brought about by the redefinition of mental illness in the context of violent behaviours. Harry highlighted this very important factor in a content analysis of DSM versions in which he measured the number of times words pertaining to violence against others or the self were mentioned (59). Harry found that the frequency in the use of these terms increased from 2.17% in DSM-I to 46.6% in DSM-III.

Link and Stueve have made the point that deficiencies from study to study tend to cancel each other out, and as such, these studies could be accepted as indicative of a potential causal relationship: that mental illness causes violence (60). To address the impact of these deficiencies, however, and in light of Monahan’s redefinition of factors to consider in a causal relationship between mental illness and violence, Arboleda-Flórez and others call for the application of strict epidemiological criteria of causality (61). They do not agree that deficiencies in studies cancel each other out but rather that they tend to perpetuate systematic errors and biases from study to study. Further, they indicate that large discrepancies between statistical models preclude strong causal inferences until a more detailed etiological theory that incorporates notions of biological plausibility could be refined and tested. They also point out that while a recent attempt to articulate the etiologic model that underlies potential associations between mental illness and violence has been presented by Hiday (62), this area remains underdeveloped. Arboleda-Flórez and his collaborators call for stricter epidemiological criteria to be applied to studies on mental illness and violence. The criteria are similar to those found in the Report on Smoking and Health from the Surgeon General of the United States (63). In this report, the Surgeon General specifies that making judgements concerning causal mechanisms requires a strict reasoning that goes beyond demonstrated statistical associations. Similar criteria have been advocated by the Federal Court of Justice in the Daubert cases on the matter of the alleged teratogenic effects of Bendectine (64). In their decision, the judges have called for strict epidemiological criteria as the only type that could be applied to make statements of causality on risk factors affecting large segments of the population.

The Risk of Violence

Monahan and Steadman quite accurately identify the risk that a mentally disordered person will commit harm to be a core issue in mental health law (65). They advocate for a public health perspective on the issue of violence; a better concatenation of predictor variables, from clinical to actuarial; and a concerted, multisite, and synchronized research effort. On the more technical epidemiological aspects, however, there are also questions about how to measure the risk. Models that examine the link between exposures and outcomes in defined populations use as a measure the relative risk, defined as the ratio of the incidence of persons exposed to a factor to the incidence of those not exposed to the factor (66). Relative risk must be calculated from prospective studies because retrospective studies lack the appropriate denominators describing the populations at risk. In the case of mental illness and violence, these studies must compare a representative sample of individuals exposed to the study factor of interest, mental illness, and at risk of the outcome, violence. Thus, the strongest epidemiological designs are based on unselected samples, incorporate the passage of time, include careful measurement of both the exposure and outcome under study, and make appropriate adjustment of confounding factors. Unfortunately, the literature review revealed that these methodological requirements have not yet been met in the study of mental illness and violence.

Yet, when members of the public consider that mental illness causes violence, they believe that they may suffer harm at the hands of mentally ill individuals. Although relative risk is used to make statements of causality (that is, “does mental illness cause violence”?), relative risk is not the best measure to quantify the risk to the population. Rather, the measure to use should be the population attributable risk (PAR) defined as the proportion of all cases that can be ascribed to a factor (67). PAR answers the important question of how much of the risk in exposed individuals can be eliminated if the exposure could be reduced or controlled. PAR is used to assess the potential benefit of preventive efforts and assesses the risks to the population at large directly and soundly. This measure addresses the sensitive question, “how much of the violence in the community can be attributed to mental illness?” Unfortunately, in the literature on mental illness and violence, only 2 authors mention this issue, and even so, peripherally (37,67).

Conclusion

The review of the literature on mental illness and violence suggests that 1) violent incidents among hospitalized mental patients are committed by a small minority of patients typically suffering from acute psychotic symptoms or dementia; 2) formerly hospitalized mental patients may be at a higher risk of arrest and violence when released into the community, particularly if they have a history of arrests or violence, or if they experience psychotic symptoms; 3) substance abuse appears to be a significant risk factor for violence and criminality among community, patients, and offender populations; and 4) family members (not the general public) are the most likely targets of violence by  formerly hospitalized patients in the community.

Estroff and others remind us, however, that not all crime committed by mentally ill persons should automatically be ascribed to the mental illness (68); contextual factors might have triggered a legitimate response, expected even from a person without a mental illness. This raises the matter of stigma and, because research may inform the legislative debate, of the potential damage to mentally ill individuals and their relatives caused by poorly designed research in this area of inquiry. Arboleda-Flórez and others indicate that the many covariations that naturally affect the equation between mental illness and violence introduce uncertainties in establishing causality (70). In their opinion, causal inferences are supportable by the empirical evidence of well-designed and well-executed research only if no compelling disconfirming evidence can be found. The field is still far from this goal.

Clinical Implications

Limitations

Acknowledgements

A part of this paper is based on Mental Illness and Violence: Proof or Sterotype?, commissioned and supported by the Health Promotions and Programs Branch of Health Canada (ISBN 0-662-24073-1, Cat. No. H39-346/1996E).

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Résumé

Objectif : Effectuer l’analyse critique de la documentation en matière de maladie mentale et de violence, examiner si la preuve suffit à établir un lien causal et fournir des renseignements épidémiologiques pour mesurer le niveau de risque de la population.

Méthode : D’après une recherche informatisée de la documentation sur la maladie mentale et la violence menée au préalable pour Santé Canada, on a procédé à une analyse critique des études en la matière et divisé celles-ci en trois catégories : 1) les études sur le comportement violent et criminel chez les patients psychiatriques, 2) les études sur la maladie psychiatrique chez les contrevenants (études de la prévalence dans les établissements, études analytiques et suivi communautaire des contrevenants) et 3) les études épidémiologiques axées sur la communauté sur la question de la maladie mentale et de la violence (rencontres entre la police et les citoyens, échantillons représentatifs et autres études épidémiologiques). Les règles de causalité et les mesures de risque ont ensuite été appliquées à la preuve obtenue.

Résultats : L’examen de la documentation suggère que seule une infime minorité des patients hospitalisés, habituellement ceux qui souffrent de symptômes psychotiques aigus, sont impliqués dans des incidents violents. Les patients qui ont déjà été hospitalisés sont à risque accru de commettre des actes violents s’ils ne sont pas traités adéquatement et qu’ils se sentent envahis par la menace de leurs symptômes psychotiques. Les troubles de toxicomanie augmentent considérablement le risque de violence. Les membres de la famille sont les victimes éventuelles les plus à risque.

Conclusions : Il existe une association entre la maladie mentale et la violence, mais les nombreuses covariations qui influent naturellement sur l’équation entre les deux facteurs provoquent des incertitudes quant à la causalité.

A part of this paper is based on Mental Illness and Violence: Proof or Stereotype?, by J Arboleda-Flórez, H Holley, and A Crisanti, commissioned by the Health Promotions and Programs Branch of Health Canada.

Manuscript received September 1998.

1Professor and Head, Department of Psychiatry, Queen’s University, Kingston, Ontario.

Address for correspondence: Dr J Arboleda-Flórez, Hotel Dieu Hospital, 166 Brock Street, Kingston, ON  K7L 5G2

email: ja9@post.queensu.ca

Can J Psychiatry, Vol 43, December 1998