Inter-Individual Variability of Executive Functioning: a Possible Key to Understand Adaptive Behavior Across ASD and ADHD.

Executive functions (EF) are neurocognitive processes frequently impaired in children with neurodevelopmental disorders, and that significantly impact on their adaptive functioning. This study investigated the relationship between executive functions and adaptive behaviors in 98 Italian preschoolers diagnosed with Autism Spectrum Disorder (ASD), Attention Deficit Hyperactivity Disorder (ADHD), or co-occurring ASD + ADHD. Utilizing both performance-based tasks and parent-reported questionnaires, the research aimed to: 1) examine associations between EF and adaptive behavior across the sample, 2) delineate distinct EF and adaptive functioning profiles within each diagnostic group, and 3) assess the mediating role of EF in the link between diagnosis and adaptive outcomes. Results indicated significant correlations between parent-reported executive behaviors and adaptive skills, highlighting a strong link between lower executive functioning and poorer adaptive outcomes. Diagnostic group comparisons revealed that children with ADHD and ASD + ADHD exhibited greater impairments in executive behaviors, particularly in inhibition and working memory, compared to those with ASD alone. The ASD + ADHD group consistently demonstrated the most severe difficulties across nearly all adaptive behavior domains compared to either single-diagnosis group. Mediation analyses indicated that global executive behaviors significantly mediated the relationship between diagnostic group and adaptive functioning. Findings highlight the critical role of EF in adaptive skills and support EF-focused interventions, to enhance adaptive skills in young children with these neurodevelopmental disorders.