Dissociable Patterns of Atypical Error Monitoring in Developmental Dyslexia and Attention Deficit Hyperactivity Disorder

This study investigated whether alterations in error monitoring constitute shared risk factors for developmental dyslexia (DD) and attention deficit hyperactivity disorder (ADHD). A total of 148 children were recruited and categorized into four groups, including 37 children with DD only, 37 with ADHD only, 40 with comorbid DD + ADHD, and 34 typically developing (TD) controls. Participants completed a combined Flanker–No-Go task to assess error monitoring, utilizing post-error slowing (PES) and post-error accuracy (PEA) to index error detection and error regulation, respectively. Results of linear mixed-effects models showed a significant main effect of DD_status on PES, indicating that children with DD (including the DD-only and comorbid DD + ADHD groups) exhibited significantly shorter PES than their non-DD counterparts. Conversely, a significant main effect of ADHD_status was observed on PEA, where children with ADHD showed lower PEA relative to those without ADHD. Notably, there were no significant differences in error monitoring functions between children with single disorders and those with comorbidities. Furthermore, hierarchical regression analyses demonstrated that PES independently predicted character recognition, but not ADHD symptom severity. These findings suggest that while both DD and ADHD involve atypical error monitoring, the underlying patterns are dissociable. Specifically, the DD profile tended to align with altered error detection, whereas the ADHD profile was more closely associated with reduced error regulation. Crucially, the comorbid group exhibited a combination of the error monitoring problems observed in DD and ADHD.