Two studies on the prevalence and validity of personality disorder in three forensic intellectual disability samples

Lindsay, William R. and Hogue, Todd E. and Taylor, John L. and Mooney, Paul and Steptoe, Lesley and Johnston, Susan and O'Brien, Gregory and Smith, Anne H. W. (2006) Two studies on the prevalence and validity of personality disorder in three forensic intellectual disability samples. Journal of Forensic Psychiatry & Psychology, 17 (3). pp. 485-506. ISSN 1478-9957

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Official URL: http://dx.doi.org/10.1080/14789940600821719

Abstract

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

Item Type:Article
Additional Information: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
Keywords:Personality disorder, Intellectual disability, Offenders, Forensic science
Subjects:C Biological Sciences > C800 Psychology
L Social studies > L340 Disability in Society
C Biological Sciences > C890 Psychology not elsewhere classified
B Subjects allied to Medicine > B761 Learning Disability Nursing
C Biological Sciences > C840 Clinical Psychology
Divisions:College of Social Science > School of Psychology
ID Code:970
Deposited By: Bev Jones
Deposited On:13 Jul 2007
Last Modified:13 Mar 2013 08:24

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