A – 67 Examining the Impact of Autism Spectrum Disorder Severity and Attention-Deficit Hyperactivity Disorder Severity on Executive Functioning in Children and Adolescents

Abstract Objective This review examines how symptom severity in Autism Spectrum Disorder (ASD) and Attention-Deficit/Hyperactivity Disorder (ADHD) differentially affects executive functioning (EF) in children and adolescents, with emphasis on working memory, cognitive flexibility, and inhibitory control across developmental trajectories. Method Data sources included peer-reviewed articles from PsycINFO, PubMed, ERIC, and Scopus databases using search terms related to ASD, ADHD, executive function, severity, and developmental stages. Studies were selected that investigated executive functioning in ASD and/or ADHD populations, employed standardized assessment measures, and reflected contemporary diagnostic criteria. Exclusion criteria encompassed theoretical papers without new data, case studies with fewer than three participants, and studies primarily addressing adult samples. Results Analysis revealed that ASD severity correlates with pronounced deficits in spatial working memory and cognitive flexibility, while ADHD severity, particularly hyperactivity-impulsivity, exacerbates inhibitory control deficits. Cross-diagnostic comparisons identified both shared vulnerabilities and disorder-specific EF profiles. Methodological limitations included overrepresentation of high-functioning individuals, limited longitudinal data, and ecological validity concerns in assessment approaches. Conclusion Severity of core symptoms consistently functions as a moderating factor that intensifies specific EF challenges in both conditions. Findings support the development of severity-calibrated assessment protocols and personalized interventions targeting distinct EF vulnerabilities. Future research should implement severity-stratified sampling, extend longitudinal designs across key developmental transitions, and develop ecologically valid assessment approaches applicable across diverse presentations.