• A comparison of offenders with intellectual disability across three levels of security

      Hogue, Todd E.; Mooney, Paul; Johnston, Susan J. (2006)
      BACKGROUND: A number of authors have described, with disparate results, the prevalence of people with intellectual disability and their characteristics, in a range of offender cohorts defined by service use. These have included high security, a range of criminal justice services and community services. There is a need for research comparing cohorts of offenders with intellectual disabilities across different settings. AIM AND HYPOTHESIS: To conduct such a comparison and test the hypothesis that severity of characteristics measured will be highest in highest levels of residential security.
    • Antisocial and psychopathic personality disorders in forensic intellectual disability populations: What do we know so far?

      Morrissey, Catrin (2011)
      Antisocial personality disorder (APD) and the more severe personality disorder of psychopathy both have particular relevance to forensic populations, but it is only recently that these constructs have begun to be explored in forensic populations who have intellectual disabilities. This paper reviews the emerging theoretical and empirical evidence in this field. Consideration is given to conceptual issues, the validity of the constructs, and emerging evidence for reliability and validity of existing measures in this particular forensic group. The lack of treatment outcome studies with respect to APD and psychopathy in this group is noted. While these constructs may be useful in understanding and treating some offenders with intellectual disability, these such labels can also result in negative outcomes for individuals. Caution is indicated in their broad application until further relevant research is completed.
    • Applicability, reliability and validity of the Psychopathy Checklist-Revised in offenders with intellectual disabilities: Some initial findings

      Morrissey, Catrin; Hogue, Todd E.; Mooney, Paul; Johnston, Susan J. (2005)
      As apart of a larger study, the Psychopathy Checklist-Revised (PCL-R) was used to assess psychopathy in 203 individuals from three UK National Health Service settings for offenders with intellectual disabilities (ID): a high security hospital, a medium and low security hospital and a community based service. The PCL-R was rated from file review combined with a clinician interview. Internal consistency and inter-rater reliability were acceptable, and broadly comparable to that reported for other offender populations. The instrument was also associated in largely expected ways with level of security, and with measures of antisocial personality disorder, risk, and current behavioural functioning, providing some preliminary indications of convergent validity. However, further empirical investigation is required before the PCL-R can be used with confidence to make clinical and risk-based decisions in this population. (PsycINFO Database Record (c) 2016 APA, all rights reserved)(journal abstract)
    • Structural, item, and test generalizability of the psychopathy checklist--revised to offenders with intellectual disabilities

      Morrissey, Catrin (2010)
      The Psychopathy Checklist-Revised (PCL-R) is the most widely used measure of psychopathy in forensic clinical practice, but the generalizability of the measure to offenders with intellectual disabilities (ID) has not been clearly established. This study examined the structural equivalence and scalar equivalence of the PCL-R in a sample of 185 male offenders with ID in forensic mental health settings, as compared with a sample of 1,212 male prisoners without ID. Three models of the PCL-R's factor structure were evaluated with confirmatory factor analysis. The 3-factor hierarchical model of psychopathy was found to be a good fit to the ID PCL-R data, whereas neither the 4-factor model nor the traditional 2-factor model fitted. There were no cross-group differences in the factor structure, providing evidence of structural equivalence. However, item response theory analyses indicated metric differences in the ratings of psychopathy symptoms between the ID group and the comparison prisoner group. This finding has potential implications for the interpretation of PCL-R scores obtained with people with ID in forensic psychiatric settings.;
    • Two studies on the prevalence and validity of personality disorder in three forensic intellectual disability samples

      Hogue, Todd E.; Mooney, Paul; Johnston, Susan J. (2006)
      There is an extensive research literature on the association between personality disorder, antisocial personality disorder, and risk of future violent and sexual offences. Several studies have found an elevated prevalence of personality disorder diagnoses amongst those individuals with severe mental illness and criminal populations. While there has been some work on the prevalence of personality disorder among intellectual disability populations, it has been criticised as being unreliable and inconsistent. The present authors have taken account of these criticisms and recommendations in this comparison of 164 offenders with intellectual disability across three settings - community, medium/ low secure, and high secure. In Study 1, DSM-IV diagnoses were made on the basis of four information sources: file review, interview with clinician, observations by care staff, and the Structured Assessment of Personality Interview. Across the samples, total prevalence of PD was 39.3%. The most common diagnosis was antisocial personality disorder. There was a higher rate of diagnosis in the high security setting, with no significant differences between the other two settings. There was no diagnosis of dependent PD, indicating that assessors were not overly influenced by the developmental disability itself. In Study 2 it was found that increase in severity of PD (as indicated by PCL-R scores and/ or the number of PD diagnoses) showed a strong lawful relationship with instruments predicting future violence (VRAG, RM 2000/V) and a weaker relationship with instruments predicting future sexual offences (Static-99, RM 2000/S). The results indicate the utility of PD classification in this client group and that a number of individuals with PD classification are being managed successfully in community settings. These findings have considerable implications for staffing, both in terms of which individuals can be treated by these services and staff training.