Do executive functions differentiate Iranian children with attention-deficit/hyperactivity disorder with and without comorbid obesity?

Abstract

To compare multiple dimensions of executive function between children with attention-deficit/hyperactivity disorder (ADHD) with and without comorbid obesity. Participants were 90 Iranian children (ages 8-13, 50% female) who were equally dispersed across three study groups: typically developing (TD), ADHD with obesity (ADHD+O), and ADHD without obesity (ADHD-O). Study participants were administered a comprehensive battery of Iranian-adapted "cool" executive function tasks including Digit Span from the Wechsler Intelligence Scale for Children-Fifth Edition (WISC-V), Victoria Stroop Test (VST), Wisconsin Card Sorting Test (WCST), Tower of London, and dot-probe task (i.e., a task of attentional bias). Parents completed the Children's Scale for Future Thinking Questionnaire, which assesses future-oriented cognition (e.g., saving, planning, episodic foresight, delay of gratification), aligning more with "hot" executive functions. Groups were compared using multivariate and post-hoc univariate general linear models. Significant group effects were observed for all executive function variables, broadly with the gradient pattern of TD > ADHD-O > ADHD+O. ADHD+O had poorer performances than ADHD-O for WISC-V Digit Span (d = -0.84), WCST Categories Completed (d = -0.55) and Perseverative Responses (d = 1.15), VST Interference Errors (d = 0.83) and Interference Time (d = 1.38), and Dot-Probe Task (d = 0.84). Relative to the ADHD-O group, ADHD+O had also poorer parent-reported Prospective Memory (d = -0.62), Episodic Foresight (d = -0.63), and Delay of Gratification (d = -0.54). Children with ADHD-O have poorer executive functioning than those without obesity. We observed stronger effects for "cool" rather than "hot" domains of executive function, though this could be due to the former being performance-based and the latter parent-reported.