Structural Validity of the Psychopathology in Autism Checklist Among Children and Adolescents.

Researchers tested a mental health assessment tool called the PAC with 600 children who have intellectual disabilities, including 194 with autism. The tool showed good reliability for measuring mental health problems in most areas (except psychosis symptoms). The PAC worked well alongside other standard assessments and appears suitable for evaluating mental health in autistic children with intellectual disabilities.

This validation study examined the Psychopathology in Autism Checklist (PAC) among 600 children aged 2-19 years with intellectual and developmental disabilities, including 194 with autism spectrum disorder. The research assessed the PAC's structural validity and internal consistency using confirmatory factor analysis. Results showed acceptable fit indices for a three-factor solution, with adequate internal consistency for most subscales (except psychosis). The PAC demonstrated meaningful relationships with established measures including the Strengths and Difficulties Questionnaire, Vineland Adaptive Behaviour Scales, IQ assessments, and autism symptom measures.

The findings provide preliminary support for using the PAC to assess mental health in autistic children and adolescents with intellectual disabilities.

The PAC appears to be a promising tool for assessing mental health in autistic children with intellectual disabilities. Clinicians should exercise caution when interpreting the psychosis subscale. Further validation studies are needed before widespread clinical implementation, but the tool shows potential for improving mental health assessment in this underserved population.

This is the first validation study of the PAC in this population, providing only preliminary evidence. The psychosis subscale showed poor internal consistency. The study focused on structural validity but did not examine other important psychometric properties like test-retest reliability or sensitivity to change.

The use of instruments developed for people with autism spectrum disorder (ASD) and intellectual and developmental disabilities (IDDs) is recommended for assessing mental health in these groups. This is the first study to investigate the structural validity and internal consistency of the Psychopathology in Autism Checklist (PAC) among autistic children and adolescents with IDDs. A total of 600 children aged 2-19 years (M = 9.2 years, SD = 4.5 years, 66% male) with IDDs (full-scale IQ M = 81.29, SD = 18.65) participated, including 194 individuals with ASD. Parents completed the PAC, Strengths and Difficulties Questionnaire (SDQ) and Vineland Adaptive Behaviour Scales (VABS).

Full-scale IQ was assessed using an individualised intelligence test, and the extent of autism characteristics was assessed using the Autism Diagnostic Observation Schedule-2. Confirmatory factor analyses revealed acceptable fit indices for a three-factor solution. The internal consistency was adequate for most of the PAC subscales. The PAC showed meaningful overlap and differentiation with the SDQ, VABS, measures of intellectual functioning and a measure of autism symptoms.

Overall, satisfactory internal consistency and validity were found for the PAC (with the exception of the psychosis subscale). These findings provide preliminary support for the use of the PAC in children and adolescents with ASD and IDDs.