Mental Illness and Violence: Proof or Stereotype?

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Appendix A: Annotated Bibliography cont'd

Studies based on Samples of Incarcerated Offenders

The following studies have examined samples of incarcerated offenders. Because they focus only on selected populations of incarcerated offenders, they cannot be used to draw etiological inferences concerning the general relationship between mental illness and violence.

Abram, K.M. and Teplin, L.A. (1990). Drug disorder, mental illness, and violence. NIDA Research Monograph, (REA 228).

Purpose and Objective: This study examined whether persons with dual diagnoses (both drug use and mental disorder) commit more violent crimes than persons who abuse drugs but who are not mentally ill. A number of combinations of drug use and psychopathology were also examined for proneness to violent crime.

Research Design: A three year cohort study.

Setting: Cook County Department of Corrections, Chicago, Illinois, United States of America.

Study Subjects: Data were collected between  November 1983 and November 1984 on a random selection of pre-trial male detainees and offenders sentenced for less than one year on misdemeanour charges. Results were presented on 728 subjects.

Measures: Information on drug abuse and mental disorders was collected using the Diagnostic Interview Schedule (DIS). Subsequent arrest and conviction data were obtained from the Chicago Police Department, the Federal Bureau of Investigation, and the Illinois Bureau of Investigation.

Main Findings: The authors constructed statistical models to predict (a) past violent behaviour, and (b) future violent behaviour. With respect to past violent behaviour, none of the drug disorders (marijuana only, opiate only, and polydrug) were found to have a significant effect on past arrests for violent crimes. Violent arrests were associated with age (given greater time at risk), lower education, and presence of antisocial personality disorder. Depressed opiate users were least likely to have violent crimes in their past. With regard to future arrests for violent crimes, the following factors were predictive: previous arrests for violent crimes, days out of jail (the greater the number of days out of jail the greater the opportunity to commit violent crimes), and opiate disorder (diminishing the probability of future arrest for a violent crime). No other factor was significant.

Conclusions: Mental disorders (schizophrenia, depression, alcohol disorder) did not predict arrest for violence, after controlling for variables (such as age or education) that are known to correlate with crime and mental disorder. In contrast, antisocial personality disorder was strongly predictive of past arrests, even after the arrest and conviction items in the DIS were removed as a basis for making this diagnosis. However, antisocial personality disorder was not predictive of future arrests. The prevalence of violent crime among drug disorders, uncomplicated by other disorders, was low, but it should be pointed out that the data were collected prior to the cocaine epidemic. (Cocaine is thought to have a relationship to violent criminality.) Authors conclude that it is the young, poorly educated, antisocial detainee with a violent past who is most likely to be involved in future violent crime.

Methodological Critique: This is a well-structured and well-executed study that employed thorough data collection techniques on a large and representative sample of subjects.

Causality: This study focuses on sub-groups of incarcerated offenders defined in terms of mental disorders and drug/alcohol abuse. While it does not provide a strong basis for drawing conclusions about the causal relationship in unselected populations, results are consistent with the view that there is no association between mental disorders and violence.

Allodi, F. and Montgomery, R. (1975). Mentally abnormal offenders in a Toronto jail. Canadian Journal of Criminology, 17, 277-283.

Purpose and Objective: Using jail medical and general records, this study sought to describe 1) all persons remanded by a court for assessment to the psychiatric unit of a jail, 2) a sub-sample taken from the first sample and who were committed, and 3) all prison records to elicit all those who, over a five year period, had a previous history of psychiatric hospitalization.

Research Design: A retrospective review of records.

Setting: A large jail in Toronto, Ontario, Canada.

Study Subjects: All those inmates (106) sent by a court for assessment to the psychiatric unit of the jail over a period of three months.

Measures: Not a standardized review of files. No specific measure used.

Main Findings: It appears that all persons remanded for an assessment were given a psychiatric diagnosis, however, this is not clearly stated. Persons with schizophrenia made up 25% of the sample, and persons with personality disorder made up 45% (25% of the total being psychopathic) of the sample. Sixty-two percent had a previous psychiatric admission, and 65% had a previous conviction. The total population of the prison for a five year period (1969-1973) having a previous psychiatric admission ranged, from year to year, from 40% to 47%.

Conclusions: A large proportion of the population in this jail had a psychiatric problem on admission, or had had a psychiatric admission prior to incarceration.

Methodological Critique: There are many problems with this study. Foremost, the sample was extremely selected; inmates who were referred for a psychiatric assessment to a jail psychiatric unit. The sample consisted of records of all inmates referred for an assessment, or previously admitted to the jail over specified periods of time. Therefore, the sample may not have been representative of the entire incarcerated population. While this study may support the notion that there is a high prevalence of mental illness among incarcerated populations, it cannot be used to make any statements about a causal relationship between criminality and violence among mentally ill individuals.

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

Arboleda-Flórez, J. (1994). An epidemiological study of mental illness in a remanded population and the relationship between mental illness and criminality. Ph.D Epidemiology Dissertation. Calgary: The University of Calgary.

Purpose and Objective: To provide estimates of one-month and life-time prevalence, to establish  estimates of comorbid conditions, and to study the relationship between mental illness and crime in an incarcerated population.

Research Design: Cross-sectional survey and secondary data analysis of all pertinent records.

Setting: A remand centre in Calgary, Alberta, Canada.

Study Subjects: Subjects were a representative sex-stratified random sample of 1200 admissions to the Calgary Remand Centre out of a total of 4770 admissions to the Centre during the study period of four and a half consecutive months (July 27 to December 10, 1992). Subjects were examined within the first twenty four hours of admission, prior to court determination. The sample size permitted estimation of mental illness to an accuracy of 1%.

Measures: Structured diagnostic interview schedules were administered by four forensic psychiatrists. Inter-rater reliability was assessed and found to be good. The Hare Psychopathology Checklist was used to augment the Structured Clinical Interview for DSM disorders (SCID). Diagnoses were assigned hierarchically.

Main Findings: Axis I or Axis II diagnoses were made in 728 cases (60.7%). Among females, the most frequent diagnosis was alcohol dependence. Major depression occurred in 26.1% of females. There were no diagnoses of schizophrenia. Among males, the most common diagnosis was alcohol dependence (31.7%). Schizophrenia was found in 1.2%, and major depression in 3.3% of males. Only 5.5% were found to have a personality disorder. The most frequently found comorbid condition was antisocial personality disorder and substance abuse disorder (4.5%). Type of charge (person, property, other) did not differ significantly among those subjects who were mentally ill and those who were not.

Conclusions: There was a high prevalence of mentally ill individuals in this sample, but this is made up mostly of alcohol and drug dependency. Socio-demographic (age, education, ethnicity) and criminological (previous detentions, previous forensic assessments) factors were related to a higher risk of being both mentally ill and criminal.

Methodological Critique: This is a study based on a representative sample of cases admitted to a remand centre, and cases at the very beginning of the justice process. The study provides compelling evidence to support the contention that a significant proportion of incarcerated persons suffer from substance abuse disorders and serious mental illness.

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

Ashford, J.B. (1989). Offense comparisons between mentally disordered and non-mentally disordered inmates. Canadian Journal of Criminality, January, 35-48.

Purpose and Objective: To compare mentally disordered and non-mentally disordered offenders on type of  offense, history of violence and criminal history in a sample of adjudicated inmates.

Research Design: Case-control on a retrospective review of files.

Setting: Maricopa County Jail system, Arizona, United States of America.

Study Subjects: Two independent samples were taken from a set of retrospective records. One sample was drawn from a list of mentally ill offenders admitted to medical or psychiatric units of the institution (cases, N=294). These inmates were further subdivided into “severely disordered” (those with a chronic diagnosis, N=82) and “mentally disordered” (those with a diagnosis during the current incarceration, N=212). Controls (N=372) came from a sample taken from the classification records of inmates not admitted to the medical or psychiatric units who were considered to be non-mentally disordered.

Measures: No measures were described. Files were reviewed with no mention of how diagnosis were entered.

Main Findings: The prevalence of recent violence among severely disordered was 36%, mentally disordered, 31%, and non-disordered, 22%. For past violence, the proportions were 14%, 10% and 7% respectively.

Conclusions: Both subgroups of mentally disordered inmates differed significantly from the non-mentally disordered group in “history of violence”. Therefore, mentally disordered inmates were considered to be more violent.

Methodological Critique: Strengths of this case-control study include: (1) having been specifically set up to compare mentally disordered to non-mentally disordered offenders on three specific variables, type of current offense, history of violence, and criminal history; and (2) the attempt to make a differentiation between “chronic cases” and “present cases” of mental pathology.

Problems in this study are multiple. This was not a representative sample. For the cases, a random sample was taken of inmates with a psychiatric history. For the controls, a random sample was taken from the files of inmates not classified as mentally ill. Possibilities exist that inmates among the controls could have been mentally ill, but not so classified. Pathology was determined from medical records without any standardization of diagnoses, raters, etc. Differences between chronic and present cases are not explained and overlapping could have easily occurred. Violence was not defined, but classified as recent or past, and its measure depended heavily on self-reports of history of violence contained in the files. Sample sizes were not justified. While findings provide some support, albeit problematic, for a relationship between violence and mental illness in incarcerated offenders, they cannot be used to infer an etiologic relationship outside of the incarcerated setting.

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

Barton, W.I. (1982). Drug histories and criminality of inmates of local jails in the United States (1978): Implications for treatment and rehabilitation of the drug abuser in a jail setting. The International Journal of the Addictions, 17(3), 417-444.

Purpose and Objective: The aim of this study was to produce a profile of jail inmates useful for classification models regarding disposition and planning for needs of jails.

Research Design: A cross-sectional survey.

Setting: Thirty seven hundred institutions across the United States of America.

Study Subjects: From a sampling frame of 165,000 inmates a weighted, non- representative sample, of 6,300 was eligible for study. The final sample consisted of 5,300 inmates.

Measures: None specified, but it appears that a special questionnaire was devised to conduct this survey.

Main Findings: About 68% had a history of drug use, and about 40% had used drugs daily. Most inmates who had used drugs were charged with property crime.

Conclusions: A substantial number of inmates in jails had used illicit drugs at some time. Only 24% had been involved in a drug abuse program. This report recommends that jails provide services for this population in conjunction with outside specialized agencies.

Methodological Critique: This was a massive undertaking, yet, the author could have been more explicit about the type of sampling used, whether it was stratified and whether the weights were taken into consideration at the time of analysis. In addition, the analysis is very superficial given the undertaking, the effort, and the resources spent in this survey. While results may be useful for program planning, they do not support a statement of causality between drugs and violence.

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

Beaudoin, M.N., Hodgins, S. and Lavoie, F. (1993). Homicide, schizophrenia and substance abuse or dependency. Canadian Journal of Psychiatry, 38, 541-546.

Purpose and Objective: This study had three main goals: (1) gather information on the relationship between consumption of alcohol or drugs and assaultive behaviour among three groups of offenders: those with schizophrenia found not guilty of homicide by reason of insanity; those with schizophrenia convicted of homicide; and non-mentally ill offenders convicted of homicide; (2) compare the history of assaultive behaviour between inmates suffering from schizophrenia and the non-mentally disordered inmates; and (3) study the link between the evolution of schizophrenia and assaultive behaviour in homicide offenders with schizophrenia found not guilty by reason of insanity, and offenders with schizophrenics who had been convicted.

Research Design: None described, but this was a cross-sectional study of a convenience sample of persons found not guilty by reason of insanity, and a cross-sectional study from a “target list” of inmates for those with schizophrenia who had been convicted of homicide. Apparently, inmates in this group were culled from a list of “target subjects” identified by the authors. Finally, homicide offenders were identified from different institutions.

Setting: The principal maximum security penitentiary hospital and three penitentiaries at medium and maximum security in Quebec, Canada.

Study Subjects: Fourteen out of 17 patients (83%) found not guilty by reason of insanity after August, 1990, 12 out of 14 offenders with schizophrenia and convicted of homicide (86%), and 15 out of 56 homicide offenders (21%), agreed to participate.

Measures: Structured Clinical Interview for DSM-III-R (SCID) was used for the second group of “target subjects”. The Diagnostic Interview Schedule (DIS) was applied to make a diagnosis of drug and alcohol history. The “Grille d'histoire d'agression physique contre la personne” (GHAP) was used to measure qualitative and quantitative aspects of aggression against the person (defined as an act implying harmful physical contact between two people, either directly, or using an object). Criminal history was determined using the official police records provided by the Royal Canadian Mounted Police. Medical files were used to ascertain diagnosis of not guilty by reason of insanity and to confirm diagnoses of schizophrenia. All subjects had to have an IQ of over 70, which was determined through the Wechsler Adult Intelligence Scale-Revised (WAIS-R).

Main Findings: Significantly, 60% of non-mentally disordered homicide offenders had a history of drug or alcohol abuse or dependency compared to 36% of those found not guilty by reason of insanity. Both groups of convicted offenders were more likely to have committed the offense while under the influence of drugs or alcohol than those found not guilty by reason of insanity. No significant difference was found among the groups for the mean number of aggressive incidents. Persons found not guilty by reason of insanity were found to be more assaultive during an acute phase of their illness compared to those schizophrenic offenders convicted of homicide. Both groups of homicide offenders had the same number of hospitalizations, but those diagnosed with schizophrenia had more hospitalizations after the crime.

Conclusions: Convicted persons with schizophrenia were very similar to those inmates who had no major mental disorder in terms of age at first conviction, consumption of drugs or alcohol, or identification of the victim. They also resembled those found not guilty by reason of insanity in IQ, diagnosis of substance abuse or dependency, number of hospitalizations, age at which schizophrenia first appeared, and choice of victim, and they  differed only with respect to age of first criminal act. Persons with schizophrenia were found to have committed criminal acts earlier than those found not guilty by reason of insanity. The earlier onset of criminality among persons diagnosed with schizophrenia may have resulted in them being labelled as criminals rather than mentally ill.

Methodological Critique: Strengths of this study include as thorough an assessment as was possible for the two mentally ill groups. Unfortunately, the study is affected by methodological errors. The design is cross-sectional, and the sample is clearly highly selected as individuals who are already defined as mentally ill and violent (for the two schizophrenic groups). It is not clear how those found not guilty by reason of insanity were selected or “targeted”. The participation of non-mentally disordered offenders was very low. In addition, no psychometric properties are given on the GHAP. It is not clear why the alcohol and drug abuse or dependency section of the SCID was not used instead of making this diagnosis via the DIS.

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

Bland, R.C., Newman, S.C., Dyck, R.J. and Orn, H. (1990). Prevalence of psychiatric disorders and suicide attempts in a prison population. Canadian Journal of Psychiatry, 35, 407-413.

Purpose and Objective: To provide prevalence estimates of mental illness in a prison population.

Research Design: Cross-sectional survey.

Setting: A remand centre and a provincial prison (inmates sentenced to two years less one day) in Edmonton, Alberta, Canada.

Study Subjects: A systematic sample of 180 males.

Measures: Diagnostic Interview Schedule (DIS).

Main Findings: Ninety-two percent of the sample had a lifetime prevalence for any disorder, with 87% being accounted for by substance abuse, including alcohol, 57% by antisocial personality disorder, and 23% by affective disorders. The prevalence of schizophrenia was estimated at 2%.

Conclusions: There was a large number of mentally disordered offenders in the prisons surveyed, but most of the pathology is accounted for by substance abuse and personality disorders.

Methodological Critique: The strengths of this study, shared only by a very few other studies in the area, lie in the choice of a representative sample, and in the care taken to make appropriate comparisons to standardized rates for sex and age and to estimates of prevalence of mental illness in the general population of the City of Edmonton. Unfortunately, the study mixed two types of correctional populations, remand and prison, which may have had an effect on the over-representation of  substance abuse cases and antisocial personality disorders. In addition, the study used DIS (based on DSM-III) criteria for diagnosis. These criteria not only over-represent cases of antisocial personality disorder (defined on the bases of criminality) among correctional populations, but also, under-represent other type of mental pathology seen most frequently among this type of population (mental conditions not included in the DIS).

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

Brownstone, D.Y. and Swaminath, R.S. (1989). Violent behaviour and psychiatric diagnosis in female offenders. Canadian Journal of Psychiatry, 34(3), 190-194.

Purpose and Objective: This study tested the hypotheses that (1) violent crime would be associated with a particular diagnosis, (2) an association would exist between the age at admission and type of crime committed, and age at admission and psychiatric diagnosis, (3) crimes committed by young offenders would be more violent than those committed by older offenders, and (4) psychiatric diagnosis would be related to the first psychiatric admission or the first crime.

Research Design: Retrospective chart review.

Setting: Forensic unit at a mental hospital in Ontario, Canada, containing the only facility for mentally ill female offenders in the province.

Study Subjects: All females (91) referred to the unit for a period of five years, January 1981 to December 1985, whether for psychiatric assessment (47), not guilty by reason of insanity or unfit to stand trial (30), probation orders (5), or transferred from a prison because of mental illness (9).

Measures: A specially constructed form was used for abstraction of data. ICD-9 diagnoses were ascertained by consensus in meetings of multidisciplinary teams.

Main Findings: A previous criminal history was recorded in 41.9% of the sample. The mean age at first conviction was 21.5 years. Violent crimes were committed by 53.8% of the sample. The great majority (72.6%) had a previous history of psychiatric admissions, and the mean age at first psychiatric admission was 24 years. Almost half (42.9%) had a diagnosis of psychosis, most often paranoid psychosis. A personality disorder was found among 35 (38.5%) of the women in the sample.

Conclusions: Offenders less than 30 years of age were more likely to be diagnosed as personality disordered, and those over 30 years of age as psychotic. No difference in age was found for violent or non-violent crimes. Diagnosis was not related to violent crime, and the type of crime was not related to age at first crime, or age at admission.

Methodological Critique: The major strength of this study lies in its being one of the few studies focused solely on women. Because subjects came from a single treatment setting, findings cannot be said to be representative of all female offenders. In addition, the sample mixes women at different points in the criminal justice process. Importantly, in the case of pre-trial remanded cases, the individual, by definition, is still innocent of a crime. Those persons found not guilty by reason of insanity and those found unfit to stand trial may also be innocent. On the other hand, individuals in post-sentenced cases, those on probation, or those in prison have been found guilty. Different selection pressures operate at each of these levels to divert some women out of the process, thereby making the findings of this study very difficult to interpret.

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

Coid, B., Lewis, S.W. and Reveley, A.M. (1993). A twin study of psychosis and criminality. British Journal of Psychiatry, 162, 87-92.

Purpose and Objective: This study tested four hypotheses: (1) schizophrenic probands have higher rates of criminality than non-schizophrenic twins, (2) schizophrenic twins have higher rates of criminality than those with affective psychosis, (3) schizophrenic twins have a characteristic pattern of offenses compared to non-schizophrenic offenders, and (4) schizophrenia predated onset of criminality.

Research Design: Retrospective follow-up based on chart review of consecutive series of individuals identified as being of twin birth (probands), and their co-twins (twin siblings), to ascertain lifetime criminal and psychiatric histories.

Setting: A major, world-famous, downtown hospital in London, England for probands and for tracing in the community of co-twins.

Study Subjects: The first analysis was conducted on 280 probands, and the second analysis (pair-wise analysis) was conducted on 220 pairs of twins. The total sample was reported to consist of 490 subjects. [Numbers do not add up due to presence of double probands (both twins with criminal records)].

Measures: Zygosity was established though serological matching or by a recognized physical resemblance questionnaire. Subjects were examined with the Schedule for Affective Disorders and Schizophrenia (SADS-L), and lifetime diagnosis assigned using DSM criteria and the Research Diagnostic Criteria.

Main Findings: Among the probands, 57.5% were diagnosed as bipolar, 35% as having schizophrenia, 2.5% as having schizophreniform, 2.5% as being paranoid, and 2.5% as having organic psychosis. In contrast, 50.4% of co-twins did not have a mental disorder. Approximately 33% had a bipolar disorder, and 9.7% had a schizophrenic or schizophreniform illness. Of the total sample of 490 individuals, 16.9% had at least one criminal conviction, and  of the probands, 21% had a criminal record. Significantly more probands had criminal convictions (25.7%) than did their respective co-twins (14%).

Conclusions: There was no effect of twin zygosity on the presence of criminality. Among ill subjects, diagnosis had a significant association with criminality. More men were criminals and schizophrenic, and more of those who were schizophrenic were criminals. Schizophrenic probands had more criminal records than bipolar probands, and were more violent. Illness preceded criminality in 57.6% of the cases. It was suggested that criminal convictions are increasing among the psychotic population.

Methodological Critique: This may be one of the few studies comparing mental illness and criminality among twins. The authors did try to find twin birth history among the probands, to find co-twins, to ascertain zygosity, and to ascertain diagnosis among the co-twins. The major flaws of the study lie in the long follow-up and the difficulties of standardizing diagnostic systems throughout the long period (40 years), and the over-representation of males in the schizophrenic group. The lack of criminal history is also problematic in the comparison between the two groups. The authors conclude that criminal convictions are increasing among the psychotic population without an appropriate comparison group.

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

Côté, G. and Hodgins, S. (1992). The prevalence of major mental disorders among homicide offenders. International Journal of Law and Psychiatry, 15, 89-99.

Purpose and Objective: To estimate life-prevalence of major mental disorders among penitentiary inmates convicted of homicide.

Research Design: Cross-sectional survey of a representative sample, and comparison of homicide offenders to non-homicide offenders.

Setting: Penitentiaries in Quebec, Canada.

Study Subjects: A representative sample of 650 inmates of whom 460 (70.8%) were interviewed and among whom 87 had been convicted of homicide.

Measures: Diagnostic Interview Schedule, DIS version III-A. Sixty-nine subjects were re-interviewed five weeks after the first interview by a different interviewer, and kappa .78 was obtained indicating good inter-rater reliability.

Main Findings: A total of 109 subjects suffered from a major mental disorder. On applying DSM-III exclusion criteria to allow only one major diagnosis per subject, more homicide subjects (35%) than non-homicide subjects (21%) suffered from a major mental disorder, usually schizophrenia. When DSM-III exclusion criteria were relaxed, recurrent major depression was more characteristic of homicide offenders. In 82% of cases with schizophrenia and 83% of those with major depression, the mental disorder  preceded the homicide.

Conclusions: The lifetime prevalence of mental disorder is higher among male offenders convicted of homicide than among other type of offenders. In the majority of cases, the mental disorder preceded the offense.

Methodological Critique: The main strength of this study pertains to the use of a representative sample. Unfortunately, however, subjects were highly selected from individuals already found guilty of an offense so do not reflect more general patterns of violence. The use of DSM-III criteria and of the DIS presents problems due to tautological definitions of violence and mental illness.  Although temporal ordering of factors is established, results are not generalizable to all violent individuals.

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

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