Inhibitory control in children with ADHD, SLD, and comorbid conditions

This study aimed to provide a comprehensive comparison of inhibitory control performance among children with Attention-Deficit/Hyperactivity Disorder (ADHD), Specific Learning Disorder (SLD), and comorbid ADHD+SLD, relative to typically developing peers. It sought to clarify whether inhibitory control deficits are generalized across tasks or specific to distinct types of inhibition. A total of 120 children (30 per group; aged 9-11 years) participated. Three tasks assessed different facets of inhibitory control: the Stroop Color-Word Test (interference suppression), the Cued Go/No-Go Task (prepotent response inhibition), and the Stop-Signal Task (cancellation of ongoing responses). Analyses controlled for baseline processing speed. Findings revealed distinct inhibitory profiles. Children with ADHD showed broad deficits across all tasks, most pronounced in the Cued Go/No-Go Task, indicating a core weakness in prepotent response inhibition. The SLD group demonstrated slower reaction times, particularly in the Cued Go/No-Go Task in the initial analysis. Slower responses reflect both processing-speed deficits and potential differences in motor planning and execution. However, after statistically controlling for these general speed effects, the SLD group's profile revealed a specific and significant deficit only in interference suppression, with no core impairment in prepotent response inhibition or action cancellation. The comorbid ADHD+SLD group exhibited the most severe and pervasive deficits across all measures, exceeding single-diagnosis groups, suggesting a synergistic impairment. These results support the multidimensional nature of inhibitory control and highlight disorder-specific neurocognitive signatures. The findings underscore the need for differentiated assessment and intervention approaches targeting distinct inhibitory processes and processing-speed deficits, particularly in children with comorbid conditions.