Abstract

Psychopathy has emerged as one of the constructs most predictive of violence risk in the forensic field. The Psychopathy Checklist-Revised (PCL-R) has previously been
found to have acceptable reliability and validity in a sample of offenders with intellectual disability, but its predictive validity in this group has yet to be established. This prospective study examined the relative ability of the PCL-R and two other instruments, the Historical Clinical Risk-20 (HCR-20) and the Emotional
Problem Scales’ Behaviour Ratings Scale, to predict officially recorded institutional aggression. A sample of 60 offenders with intellectual disability in a high security
forensic psychiatric setting was followed up for a period of 12 months. The PCL-R 20-item total, the PCL-R 13-item total, and PCL-R Factor 1 and Factor 2 scores did not significantly predict any type of aggressive behaviour. In contrast, the two more clinically based measures significantly predicted both interpersonal physical
and verbal/property aggression. A primary justification for using the PCL-R in forensic settings is the evidence for its association with violence. Further studies examining the relationship between psychopathy, aggression, and violent recidivism in broader samples of offenders with ID are therefore imperative.