Executive Functions and Writing Skills in Children With and Without ADHD

Objective: Pediatric attention-deficit/hyperactivity disorder (ADHD) has been associated with impairments in executive functioning and academic writing skills. However, our understanding of the extent to which these children's writing difficulties are related to their underdeveloped executive functions-and whether this relation is attributable to specific executive functions-is limited. Method: A clinically-evaluated and carefully-phenotyped sample of 91 children ages 8-13 (M = 10.60, SD = 1.25; 37 girls) were administered multiple, counterbalanced tests of the three core executive functions (working memory, inhibitory control, set shifting), assessed for ADHD symptoms via multiple-informant reports, and completed standardized, norm-referenced testing of three core writing skills (written expression, spelling, writing fluency). Results: Bias-corrected, bootstrapped conditional effects modeling indicated that underdeveloped working memory exerted significant direct effects on all three writing skills, as well as indirect effects on written expression and spelling via the ADHD symptoms pathway (all 95% CIs exclude 0.0). In contrast, inhibitory control uniquely predicted spelling difficulties only, set shifting was not associated directly or indirectly with any assessed writing skill, and ADHD symptoms failed to uniquely predict writing skills after controlling for working memory. This pattern of results replicated across informants (parent vs. teacher ADHD symptom ratings), and was robust to control for age, sex, socioeconomic status (SES), majority/minority race/ethnicity status, intellectual functioning (IQ), decoding skills, language skills, and learning disability status. Conclusion: These findings suggest multiple pathways to writing skill difficulties in children with ADHD, while suggesting that their overt behavioral symptoms may be less involved in their writing difficulties than their underlying neurocognitive vulnerabilities. Key Points Question: Attention-deficit/hyperactivity disorder (ADHD) is associated with executive function deficits and difficulties with academic writing skills, but are these links attributable to specific executive functions? Finding: Underdeveloped working memory abilities predicted written expression, spelling, and writing fluency, both directly and in most cases indirectly via working memory's role in regulating attentive behavior; inhibitory control predicted spelling only, whereas set shifting was not associated with a