The Role of Executive Function in the Co-occurrence of ADHD and Developmental Dyscalculia in Chinese Children

Objective: This study aimed to elucidate the characteristics of executive function deficits in children with Attention-deficit/hyperactivity disorder (ADHD) comorbid with developmental dyscalculia (ADHD+DD). Methods: Three groups of Chinese children (n = 637) aged from 6 to 16 years were included in this study. Initially, a between-group comparison on both performance-based and scale-based executive function was conducted, controlling for age, Raven score, and gender. Partial correlation analysis and regression analysis were then used to investigate the association between executive function, ADHD symptoms, and arithmetic ability. Furthermore, logistic regression analysis and path analysis were used to differentiate the effect of executive functions on ADHD without developmental dyscalculia (ADHD-DD) and ADHD+DD. Results: Both ADHD groups had more severe executive function impairment than the control group. Compared with the ADHD-DD group, the ADHD+DD group performed worse in performance-based executive functions but similar in scale-based executive functions. ADHD-DD and ADHD were differentiated by inhibition (odds ratio (OR) = 2.00, 95% CI = 1.42; 2.81) and processing speed (OR = 0.90, 95% CI = 0.84; 0.97). In terms of symptom dimensions, verbal working memory had an effect on ADHD symptoms and complex subtraction (pIna = 0.006, pHI = 0.018, pCS = 0.002), processing speed (pIna = 0.002, pCS = 0.001) and working memory factors influenced inattention and complex subtraction (pIna < 0.001, pCS = 0.001), and inhibition (p = 0.004) and cognitive flexibility (p = 0.013) contributed uniquely to complex subtraction. Conclusion: Individuals with ADHD+DD exhibit multiple executive function deficits, with inhibition and processing speed being potential etiological factors. Verbal working memory, processing speed, and working memory factors are shared executive function deficits for ADHD symptoms and arithmetic ability. Cognitive flexibility and inhibition are specific risk factors for arithmetic ability.