Autism Symptom Presentation and Hierarchical Models of Intelligence

Background: There is a substantial history studying the relationship between general intelligence and the core, diagnostic symptoms of autism. Given that hierarchical models of intelligence are used in clinical practice, one one thing that remains is unclear is at which level of these hierarchical models we find associations with the magnitude of autism diagnostic symptoms, and whether associations differ between versions of clinical intelligence quotient (IQ) tests. Method: We examined associations between autism diagnostic symptom magnitude, as measured by the Autism Diagnostic Observational Schedule (ADOS), and hierarchical models of general intelligence. Because previous work using the same cohorts demonstrated that the manualized index structure of the Wechsler Intelligence Scale for Children, fifth edition (WISC-V) and Wechsler Intelligence Scale for Children, fourth edition (WISC-IV) do not correlate well with data-driven factorization of subtest results within autism samples, our measures of general intelligence included Spearman’s g and data-driven intermediate factors derived from WISC-V (N=83) and the WISC-IV (N=131) subtest performance. Results: In the WISC-V cohort, ADOS scores did not show a significant correlation with g and correlated with only one empirically-derived factor score in this sample. On the other hand, in the WISC-IV, ADOS scores were correlated with g and three out of four factor scores. Conclusions: Autism core symptom presentation is more independent of general intelligence as measured by the WISC-V than as measured by WISC-IV at both the overall (full-scale IQ) and factor levels of the hierarchy.