Mental Illness and Violence: Proof or Stereotype?

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Appendix A: Annotated Bibliography cont'd

Studies of Psychiatric Patients

The following section includes studies of the relationship between mental illness and violence among psychiatric patients. Given that all of the study samples consist of persons who have come into contact with hospital services, the validity of the research findings in this area are threatened by selection bias. Because of this, it is never clear whether associations noted in hospitalized samples actually reflect associations that exist in the population at large. In addition, many of these studies lack a comparison group, making it impossible to assess whether rates of violence are higher or lower than would be expected. Because of the selected samples, research in this area cannot be used to substantiate the proposition that the mentally ill are more violent than the non-mentally ill.

Asnis, G.M., Kaplan, M.L., van Praag, H.M. and Sanderson, W.C. (1994). Homicidal behaviours among psychiatric outpatients. Hospital and Community Psychiatry, 45(2), 127-132.

Purpose and Objective: The aim of this study was to further qualify the assessment of violent behaviour by focusing on behaviours that the patient specifically identifies as homicidal, including homicidal ideation, plans, and attempts. The second goal was to determine those characteristics which differentiate patients with past homicidal behaviours from patients who show no homicidal tendencies.

Research Design: Although the authors did not specify, the data collection procedure is consistent with a descriptive survey.

Setting: A nonprofit hospital in Bronx, New York.

Study Subjects: The subjects for this study were 517 patients who requested treatment at the outpatient psychiatry department. There were 204 (40%) males and 313 (60%) females ranging in age from 13-87 years.

Measures: Self-rating forms were used including: (1) the Harkavy-Asnis Suicide Survey demographic form; (2) the Homicidal Behaviours Survey and; (3) the revised Symptom Checklist 90. Each patient also underwent a semi-structured interview that included a psychiatric history and mental status evaluation. These were conducted by a psychologist or psychiatrist. Patients received a DSM-III-R diagnosis.

Main Findings: A total of 114 (22%) reported past homicidal ideation, and 41 of those subjects (8% of the total sample) reported that their homicidal thoughts persisted for at least seven days. Forty subjects (8%) reported having a homicidal plan. Twenty-two subjects (4%) reported a past homicide attempt. No significant differences were found in diagnosis for those with a past homicide attempt compared to those without homicide tendencies. In addition, the homicide attempt group reported significantly more suicidal ideation and attempts compared to the homicidal ideation group. There was an 8% difference between males and females regarding homicidal ideation and attempts (males 27%, females 18%).

Conclusions: The authors concluded that the rate of homicide attempts in the current study is considerably lower than the 10% rate of physically assaultive acts reported by other researchers. Given the observed relationship between current and past homicidal behaviours, the authors advocated including a careful assessment of past history of violent behaviours as part of the routine psychiatric evaluation. The authors recognized that the inherent limitations of self-report instruments and the retrospective nature of the study limited the findings. They do not suggest that these results provide a basis for drawing conclusions about the etiology of homicidal behaviour.

Methodological Critique: The major limitation in this study is the focus on homicidal behaviour which is not only very rare but a very extreme type of violent behaviour. Despite their limited focus, the authors compare their results to studies of criminal behaviour in general and criminal behaviour among inpatient populations. Given that their study focussed on outpatients, it is not clear how such comparisons could be informative. The high proportion of females in the study population (60%), may account for the lower rate of homicide in this study compared to other research, as females tend to have a lower incidence of violent crime. In addition, given that the psychometric properties of the instruments used were not reported, conclusions regarding the reliability and validity of the findings are limited. In addition, in light of the sensitivity of the information collected, the use of a self-report instrument may underestimate homicidal tendencies in this study group. Because the study focussed on outpatients receiving treatment, findings cannot be used to examine the possibility that there is an etiological relationship between mental illness and violence.

Causality: A causal inference cannot be made on the basis of these findings.

Binder, R. McNeil, E. and Binder, R.L. (1988). Effects of diagnosis and context on dangerousness. American Journal of Psychiatry, 145(6), 728-732.

Purpose and Objective: The purpose of this study was to address the following questions: (1) Are schizophrenic patients, manic patients, or patients with other diagnoses more likely to be assaultive before admission?; and (2) are schizophrenic patients, manic patients or patients with other diagnoses most likely to be assaultive during the acute phase of hospitalization?

Research Design: The authors fail to identify the study design. It appears that they conducted a longitudinal chart review.

Setting: A locked short-term inpatient psychiatric unit in a university hospital.

Study Subjects: Subjects were 150 patients randomly selected from all patients admitted during 1983 (N = 238) and during the first 6 months of 1984 (N = 118). Multiple admissions were removed.

Measures: Pre-admission violence was defined as occurring in the two week period before hospitalization. Hospital violence was measured during the first 24 hours of hospitalization. Violent behaviour was rated on a scale which included four categories: (1) attacks on persons; (2) attacks on objects; (3) threats to attack persons; and (4) verbal attacks on persons.

Main Findings: No statistically significant differences in ethnicity or social class were found. The data showed that 21% of the patients had attacked persons and 25.3% had engaged in fear-inducing behaviour during the 2 weeks before admission. Chi-square analysis revealed a significant association between diagnosis and the occurrence  of violence, specifically schizophrenic and mania. Thirteen percent of patients attacked persons during their admission and 32% engaged in fear-inducing behaviour. A significant association between diagnosis and violence surfaced; however in this case, patients with mania were most likely to attack persons while patients with schizophrenia were most likely to engage in fear-inducing behaviour.

Conclusions: The risk of violence by different diagnostic groups was found to vary according to context. Prior to hospitalization both manic and schizophrenic patients had a higher risk of assaultive behaviour than patients with other diagnoses. However, during hospitalization, manic patients were more likely to be assaultive. During the first 24 hours of hospitalization, schizophrenic patients are given neuroleptics, which decrease psychotic symptoms and causes sedation and decreases the likelihood of violence.

Methodological Critique: The diagnostic groups compared displayed different demographic characteristics. These may have accounted for some of the differences in violence noted.

Causality: A causal inference cannot be made on the basis of these findings.

Buckley, P., Walshe, D., Colohan, H.A., O'Callaghan, E., Mulvey, F., Gibson, T., Waddington, J.L. and Conall, L. (1990). Violence and schizophrenia - a study of the occurrence and clinical correlates of violence among schizophrenic patients. Irish Journal of Psychological Medicine, 7, 102-108.

Purpose and Objective: The purpose of this study was to explore the characteristics of violent behaviour and its clinical correlates among psychiatric inpatients.

Research Design: Data were collected through a chart review. Although the authors do not specify the design, data collection procedures are consistent with a retrospective survey design.

Setting: Psychiatric inpatient department in a general hospital in Stillorgan, Dublin.

Study Subjects: The sample consisted of all patients (N = 698) with an International Classification of Diseases Ninth Edition (ICD-9) diagnosis of schizophrenia. Subjects were admitted between 1983 and 1988.

Measures: Violence was defined as either physical assault or deliberate damage to property. Violence was recorded in both the community and hospital setting. Any act occurring since the onset of the patient's illness was included.

Main Findings: Of the 698 schizophrenic patients reviewed, 113 (16.2%) had engaged in acts of violence. Patients who had been violent were compared to patients with no history of violence. The two groups were indistinguishable in terms of the presence or absence of positive and negative symptomatology, family history of psychiatric illness, or treated depression. Male patients  displayed a higher rate of violence than their female counterparts. Sufficient data were available to characterize 111 patients (out of 113) with respect to their violent acts. Twenty (18%) had been violent in hospital, 62 (56%) in the community and 29 (26%) in both settings. Most of the incidents of community violence occurred in the home and involved episodes of damage to furniture or assault on relatives. Most of the assaultive behaviour was minor.

Conclusions: The majority of violent acts were of a minor nature and seldom resulted in serious physical injury.

Methodological Critique: The authors stated that these finding are comparable to earlier research findings. The authors recognized two potential sources of sampling bias. Firstly, patients with a milder illness who were treated only as outpatients were excluded from consideration. This may have resulted in an overestimation of violence among schizophrenic patients. Secondly, patients who displayed persistent and severe violent behaviour were excluded since they were referred for treatment to regional secure units. In addition to the biases identified by the authors, it is probable that reliance on nursing notes may have underestimated violence.

Causality: A causal inference cannot be made on the basis of these findings.

Cirincione, C., Steadman, H.J., Clark-Robbins, P. and Monahan, J. (1992). Schizophrenia as a contingent risk factor for criminal violence. International Journal of Law and Psychiatry, 15, 347-358.

Purpose and Objective: This study assessed the extent to which a diagnosis of schizophrenia was predictive of criminal violence after controlling for the effects of arrest history.

Research Design: The authors failed to identify the type of research design. However, based on the data collection description, it appears that a retrospective cohort design was used.

Setting: New York State Office of Mental Health Civil Facility, New York, United States of America.

Study Subjects: The two study cohorts were adult males admitted to a New York State Office of Mental Health civil facility in 1968 and 1978. The samples included both voluntary and involuntary patients. The original sample was 400. However including only: (1) those patients under the age of 50; (2) those patients with complete records; (3) those with a DSM-III-R psychiatric disorder (excluding personality disorders) and; (4) those patients who had been released within 5 years of their target admission, the final sample sizes of the 1968 and 1978 cohort consisted of 255 and 327, respectively. The majority of the cases, 86.7% had a primary diagnosis of either schizophrenia or substance abuse.

Measures: Information was collected on each patient's diagnosis at target admission, age at admission, race, and prior arrest history. Data on subsequent arrests  was collected from the New York State Division of Criminal Justice Services for 11 years after inpatient admission. Violent crime was considered to be murder, manslaughter, rape, attempted rape, assault, kidnapping and sodomy.

Main Findings: For the 1968 cohort, the only variable significantly related to subsequent violence was prior arrest history. In the later cohort, prior arrest history was again significantly related to subsequent violence. Additionally, persons who were non-Caucasian were significantly more likely to be violent than Caucasians.

Of those diagnosed with schizophrenia and having no arrests, 10.7% were subsequently violent compared to 2.2% of those with substance abuse disorders. In the 1968 cohort, the probability of arrest for a violent crime was highest for persons with schizophrenia and lowest for patients in the other diagnostic category. For the 1978 cohort, diagnosis did not add significantly to the prediction of violence.

Conclusions: The results produced a number of interesting patterns between diagnosis and subsequent arrests for violent crimes that did not change even when controlling for age, race, and legal status. In the 1968 cohort, diagnosis was a significant predictor of violence. The results for the 1978 cohort were the opposite of those in the 1968 cohort where, for those without a previous arrest, diagnosis was not a significant predictor of violence. In this cohort, the base rate of violence for patients with no prior arrests may have been too low (2.6%) to allow for meaningful analysis. The findings suggest caution in accepting the claim that risk assessment can and should only be made when extensive prior histories of violence are present. The results also revealed that the relationship between diagnosis and violent crimes depended upon prior arrest history.

Methodological Critique: The low base rate in the 1978 cohort and the small number of non-schizophrenic patients renders the interpretation of the statistical analyses problematic. The finding that patients with a diagnosis of schizophrenia are involved in violent incidents may be simply a result of an overrepresentation of persons with schizophrenia in this hospital population relative to other diagnostic groups.

Causality: A causal inference cannot be made on the basis of these findings.

Convit, A., Isay, D., Otis, D. and Volavka, J. (1990). Characteristics of repeatedly assaultive psychiatric inpatients. Hospital and Community Psychiatry, 41(10), 1112-1115.

Purpose and Objective: The purpose of this study was to compare patients who were repeatedly violent recidivists with those who had been violent only once or twice (non-recidivists) in an attempt to uncover correlations that were more specific to violence.

Research Design: Although the researchers  failed to specify the type of study design, the data collection procedure was consistent with a retrospective cohort study.

Setting: A large state hospital in New York City, New York, United States of America.

Study Subjects: All patients in the hospital on the first day of the study and all subsequent new admissions over the six-month study period were considered at risk for violence and therefore were included in the at-risk population. The study population included 1,195 patients who were hospitalized when the study began and 357 patients who were admitted during the six-month study period, making a total at-risk population of 1,552 patients (1,041 men and 511 women).

Measures: Incident reports were used to determine occurrences of violence. In New York state psychiatric hospitals, two types of violent behaviour warranted an incident report: fights and assaults. A fight was defined as a physical altercation between two patients. An assault was defined as a physical attack by a patient in which the victim did not strike back. For this study all the incident reports for fights and assaults over the six-month period were collected. Patients who were involved in three or more such incidents were defined as recidivists.

Main Findings: During the study period, 4907 separate incidents of violent behaviour occurred, including 174 fights (35%), 233 assaults on patients (47%), and 90 assaults on staff (18%). A total of 313 different patients (201 men and 112 women) or 20% were involved in a fight or were the attacker in an assault one or more times during the six month-study. Seventy of the 313 violent patients (31 men and 39 women) met the definition of recidivism. These 70 patients accounted for 53% of all the instances of violent behaviour. The percentage of women classified as recidivist was significantly higher than that of men. While women recidivists tended to be younger, there were no significant diagnostic differences between the recidivists and non-recidivists.

Conclusions: The data from this study demonstrated that approximately 5% of the at-risk patient population were responsible for 53% of the assaults. Eight percent of the women in the hospital accounted for 70% of the assaults committed by women and 3% of the men accounted for 40% of the assaults perpetrated by men. The findings indicate that a small percentage of patients are responsible for about half of the violence in psychiatric hospitals. More importantly, they are responsible for more than half of the serious injuries.

Methodological Critique: The reliance on incident reports may have underestimated the level of violence in this population. The finding that a small proportion of the population is responsible for a large proportion of the violence is consistent with more general criminality studies. However, because this study focused on hospitalized patients, it cannot be generalized to all  persons with mental illness and therefore do not shed light on the etiological relationship of mental illness and violence.

Causality: A causal inference cannot be made on the basis of these findings.

Cuffel, B.J., Shumway, M, Chouljian, T.L. and Macdonald, T. (1994). A longitudinal study of substance use and community violence in schizophrenia. The Journal of Nervous and Mental Disease, 182(12), 704-708.

Purpose and Objective: This study was designed to address two questions: (1) whether substance use in schizophrenia could be cross-sectionally related to the occurrence of violent behaviour; and (2) whether substance use in schizophrenia could predict the occurrence of future violent behaviour.

Research Design: A retrospective record review was used to collect secondary data reported and documented during the course of randomized controlled trials.

Setting: A schizophrenia research clinic at San Francisco General Hospital, San Francisco, United States of America.

Study Subjects: Study subjects were 103 psychiatric outpatients who were between the ages of 18-55 years and received care between 1985 and 1989. All subjects were participants in a clinical trial of pharmacological interventions which excluded individuals with extensive legal histories or those dependent on alcohol or drugs. At 6 months, 89 patients remained in the study. Beyond 6 months, sample attrition made statistical analyses too imprecise.

Measures: All data were collected using a retrospective chart review. Study subjects had a DSM-III-R clinical diagnosis of schizophrenia, schizoaffective disorder or schizophreniform disorder recorded on their charts. These diagnoses were initially made using a Structured Clinical Interview. Violent behaviour that was recorded on the clinical file between 1-3 months and between months 3-6 comprised the main dependent measures. These included verbal threats to harm others, non-verbal threats to harm others, physical assaults, altercations, brandishing a weapon, using a weapon, starting a fire, and destroying property. Substance abuse was recorded separately for alcohol, marijuana, opiate, sedative, and hallucinogen use. Subjects were classified into those who used only alcohol or marijuana (N=9) and those using some other substance (N=11). Age, sex, and minority status were considered to be covariates in the analysis.

Main Findings: During the first 3 months, 8.6% of subjects were identified as having used alcohol or marijuana and 10.6% were found to have patterns of use of more than one substance (polysubstance abuse). During the 3-6 month period of the study, these proportions were 11.3% and 5.7%, respectively. Violent behaviour was recorded in 18.4% of the sample in months 1-3, and 14.7% in months 3-6. Polysubstance abusers were reported to be 12.56 times (p  .01) more likely to commit a violent act in the first 3 months of follow-up and 4.61 times (p .10) more likely to commit a violent act during the second 3 months of follow-up. No other statistically noteworthy relationships were reported.

Conclusions: The authors conclude that the results from this study provide “presumptive evidence” that use of some substances may predispose individuals with schizophrenia and polysubstance use to later episodes of violent behaviour.

Methodological Critique: The restricted nature of the sample, the small sample sizes and the lack of reported confidence intervals make the importance of these findings difficult to judge.

Causality: This study does not address the question of whether persons with schizophrenia are at higher risk of violence than those without a mental disorder. Thus, results cannot be used to make any causal inferences about mental disorder and violence.

Durbin, J.R., Pasewark, R.A. and Albers, D. (1977). Criminality and mental illness: A study of arrest rates in a rural state. American Journal of Psychiatry, 124(1), 80-83.

Purpose and Objective: This study examined cumulative arrests for ex-psychiatric patients and compared these to the general population.

Research Design: The authors do not name a design but data collection procedures are consistent with a historical cohort with variable follow-up spanning up to 10 years.

Setting: Wyoming, United States of America.

Study Subjects: Study subjects were 461 persons aged 18-64 years admitted to the Wyoming State Hospital during the 1969 calendar year. Excluded from the study were admissions resulting from forensic/court remands for psychiatric assessment, persons transferred to other institutions during the course of the study, and those who died while in hospital. The Wyoming State Hospital is the only psychiatric facility in the state, therefore, findings are generalizable to the population of psychiatric patients in Wyoming.

Measures: Criminal arrest data were obtained for the period 1964-1973 for the study cohort (based on fingerprint match) and for the state population.

Main Findings: Findings show different arrest patterns among male and female patients. Overall, male ex-patients were more likely to be arrested and women were as likely to be arrested as the general population. A small number of male patients were responsible for the bulk of arrests in this group: 7.3% of the patients were responsible for 68.2% of the arrests. Male patients appear to have higher rates for violent crimes compared to the general population in most crime categories. However, men diagnosed with personality disorder or drug dependence contributed disproportionately to arrests. Persons with  personality disorder comprised 10.1% of the cohort but 25% of the arrests and those with drug dependence accounted for 3.5% of the patients but 7.9% of the arrests. Persons with schizophrenia were not overly represented in the arrest records and none of the arrests were for crimes against people.

Conclusions: The authors indicate that definite conclusions and generalizations from this type of research are risky because of the multitude of factors that influence arrest rates. Findings were interpreted to suggest that mental patients were not arrested less frequently than the general population, as some previous research had suggested.

Methodological Critique: This study corrected for the fact that patients were not at risk for arrest while they were institutionalized. The different rates of arrest noted for men and women highlights the importance of controlling for demographic differences when comparing to general population data.

Causality: Given the selected nature of the study cohort, findings cannot be interpreted to reflect an causal relationship between mental illness and violence.

Fottrell, E. (1980). A study of violent behaviour among patients in psychiatric hospitals. British Journal of Psychiatry, 136, 216-221.

Purpose and Objective: The purpose of this study was to examine violent behaviour among patients in British psychiatric hospitals.

Research Design: The researchers do not specify what design was employed. It appears to be case-control given that subjects were recruited into the study based on the occurrence of a violent incident.

Setting: The study was carried out in Tooting Bec Hospital in London, the Chiltern Psychiatric Wing of Sutton General Hospital in Sutton, and Park Prewett Hospital, in Basingstoke, Hants. At the first and second hospital, the study continued for one year and covered the total patient population. In the third hospital, the study occurred over a four month period.

Study Subjects: Both Tooting Bec and Park Prewett hospitals had populations of approximately 1100 patients at the time of the study.

Measures: The type of violence studied was intentional personal physical violence, including that to the self. Three degrees of violence were identified. Violence of the first degree was present when no physical injury was detectable or suspected in the victim when examined by the doctor. Second degree violence was when minor physical injuries were present. The third degree included incidents where physical injury was found or suspected in the victim. A questionnaire was developed to capture occurrences of violence.

Main Findings: More younger age groups and females were responsible for the violent incidents. Schizophrenia was the most common diagnosis among the  offending patients. Only a small percentage of the total patient populations behaved violently and a smaller percentage of patients were responsible for a large percentage of the incidents.

Conclusions: While incidents of petty violence occur in psychiatric hospitals, serious assaults are rare. The three serious incidents which occurred were suicide. The authors concluded that in these hospitals one is at much greater risk of dying by one's own hand than by the hand of another.

Methodological Critique: Because results were based on patient samples, they cannot be used to infer violence to non-hospitalized persons with mental illness. Nevertheless, it is interesting to note that the incidence of violence was considered to be low in a group that would be expected to be at higher risk of violence. This could be due to under-detection.

Causality: A causal inference cannot be made on the basis of these findings.

Grossman L.S., Haywood T.W., Cavanaugh J.L., Davis J.M. and Lewis D.A. (1995). State psychiatric hospital patients with past arrests for violent crimes. Psychiatric Services, 46(8), 790-795.

Purpose and Objective: To compare the prevalence of criminality and violent crime among four groups of patients: patients diagnosed with schizophrenia; schizoaffective disorder; bipolar affective disorder; and unipolar affective disorder.

Research Design: Review of arrest records of hospitalized mental patients.

Setting: Four state psychiatric hospitals in Illinois, United States of America.

Study Subjects: Study subjects were 172 inpatients who were interviewed during their voluntary hospitalizations as part of a longitudinal research program. These individuals were identified from a random sample of 313 patients as meeting the study's diagnostic inclusion criteria.

Measures: Patients were diagnosed with the RDC (Research Diagnostic Criteria) and DSM-III, and selected via the Schedule for Affective Disorders and Schizophrenia (SADS). Criminal history was determined based on arrest records from the Chicago Police Department. Patients were classified according to the most violent crime for which they were arrested prior to hospitalization.

Main Findings: Of the 172 study subjects, 63.5% had no prior criminal history, 3% had committed only non-violent crimes, 6.5% had committed crimes against property, and 27% had committed crimes of violence. A significant association between diagnostic category and past crimes of violence was found. Patients with schizoaffective disorders were more likely to have been arrested for a violent offense. Patients who were considered to be psychotic during their hospitalization were significantly  more likely to have a history of violent crime than non-psychotic patients. Comparing only patients with paranoid schizophrenia to those with non-paranoid schizophrenia, those with paranoia were significantly more likely to have committed a violent crime. In addition, patients who abused drugs or both drugs and alcohol committed more serious crimes. Finally, past history of violent crime was more common among male patients from minority groups.

Conclusions: Demographic features, a diagnosis of schizoaffective disorder, psychosis, paranoid symptoms, and substance abuse may all be associated with violent behaviour.

Methodological Critique: It is not clear whether patients were symptomatic at the time of their arrests, or whether their psychiatric illness predated their criminality.

Causality: The highly selected sample of psychiatric inpatients and the lack of temporal ordering of study factors makes it impossible to draw general statements of causality from these findings.

Guze, S.B., Woodruff, R.A. and Clayton, P.J. (1974). Psychiatric disorders and criminality. Journal of the American Medical Association, 227(6), 641-642.

Purpose and Objective: The purpose of this study was to address the question, “What kinds of psychiatric disorders are associated with criminality?”

Research Design: Although the authors did not specify, the data collection procedure is consistent with a retrospective survey design.

Setting: The authors did not indicate the study setting.

Study Subjects: A sample of 500 patients of a psychiatric clinic population.

Measures: Data was collected from a chart review describing the results of an interview that had been previously conducted. This interview included a section dealing with “trouble with police”or imprisonment.

Main Findings: Twenty-two patients had a history of at least one felony conviction (4%). A significant difference was found between men and women. Six of the 22 patients, all men, were convicted because of behaviour resulting from sexual deviation. Five of these men had no other psychiatric diagnosis. Fourteen of the remaining 16 patients were either sociopathic (N = 13), alcoholic (N = 8) and/or drug dependant (N = 3). None of the patients with either schizophrenia or primary affective disorder reported a felony conviction.

Conclusions: Results are consistent with those previously obtained from studies of convicted felons. Sociopathy, alcoholism, and drug dependence were the principle psychiatric disorders associated with serious crime. These findings suggest that psychiatrists must deal chiefly with sociopathy, alcoholism, and drug-dependence in order to prevent and treat criminality.

Methodological Critique: Misclassification bias is the major threat to the internal validity of this study. Relying on self-report measures for assessing criminal behaviour increases the chances of underreporting. Findings must be interpreted as limited to psychiatric patients.

Causality: A causal inference cannot be made on the basis of these findings.

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