Date of Award
2025
Document Type
Open Access Dissertation
Department
Psychology
First Advisor
Jane Roberts
Abstract
Intellectual functioning constitutes a significant source of heterogeneity in individuals with autism spectrum disorder (ASD); however, little is known about how intellectual functioning manifests over development in preschool children with non-syndromic ASD (nsASD) and co-occurring global developmental delay (GDD) or how this relates to functionally impairing co-occurring conditions, such as anxiety. Study participants included 57 children with nsASD and co-occurring global developmental delay (ASD+GDD), 24 categorized with mild GDD, and 33 categorized with moderate GDD. Drawing on dynamic systems theory, the present study explored developmental trends within the context of multiple complex systems, including intelligence, social-emotional, and behavioral functioning. Moderated regressions were used to examine FSIQ, NVIQ, and VIQ trends in a cross-sectional design. Logistic regressions were used to explore the relationship between VIQ, NVIQ, ASD symptom severity, and anxiety disorder diagnoses in a smaller subset of 34 children with ASD+GDD. Findings suggest nuanced relationships between ASD symptom severity, GDD severity, and IQ scores, highlighting significant variability within the ASD+GDD phenotype. In addition, high rates of anxiety across GDD severity groups not driven by ASD symptom severity or IQ were identified. Study findings fill a significant gap in the literature by identifying IQ trends and anxiety prevalence in an understudied, high-needs sample of autistic preschoolers. Clinical implications are discussed.
Rights
© 2025, Chandler Elizabeth Knott
Recommended Citation
Knott, C. E.(2025). IQ Trends in Preschoolers with Autism and Co-Occurring Developmental Delay Are Associated with Autism Severity Not Anxiety. (Doctoral dissertation). Retrieved from https://scholarcommons.sc.edu/etd/8574