Validation of the Psychopathy Checklist Short Version in Autistic Adults Detained Under the Mental Health Act, 1983.

Background and aims: Limited understanding exists regarding the relationship between autism and psychopathy, especially within the criminal justice system. A systematic review was completed which aimed to better understand the relationship between psychopathy and autism, and to describe the clinical manifestation of the two constructs when they co-occur. This highlighted that co-occurring autism and psychopathy leads to additional empathic impairment. However, studies were characterised by measurement difficulties, underscoring the need for improved methods for identifying psychopathic traits in autistic individuals. The Psychopathy Checklist Short Version (PCL:SV) is a brief measure of psychopathy. This study sought to validate the PCL:SV within autistic adults detained under the Mental Health Act, 1983, by examining construct, predictive and convergent validity. Method: Secondary data analysis was completed using data from 282 autistic adults, detained in secure psychiatric care. Reliability and validity were investigated using regression, receiver operating characteristic curves and correlation analysis. Results: High reliability and construct validity was found, particularly for PCL:SV Total and Factor 1. Higher PCL:SV scores were associated with a decreased likelihood of discharge and increased likelihood of negative/no change across security wards, which can indicate treatment progress. Predictive validity for aggressive or problematic behaviours was limited, although significant area under the curve results were observed for several specific behaviours. Factor 2 was the strongest predictor of aggressive or problematic behaviours. The measure correlated as expected with other risk assessment tools. Conclusions: Accurate measurement of psychopathy in autistic adults within forensic pathways will support the development of appropriate care pathways for individuals at risk of committing violent crimes. This study provides preliminary evidence for the use of the PCL:SV with autistic adults detained under the Mental Health Act, 1983, but caution is warranted until further research is completed, including confirmatory factor analysis and Rasch analysis.