Executive functions underlie word reading and reading fluency in Chinese children with attention deficit/hyperactivity disorder, reading disabilities, and comorbid attention deficit/hyperactivity disorder and reading disabilities

The current study examined the executive function (EF) deficits and their roles in reading in one hundred and four Cantonese-speaking children with typical development, reading disabilities (RD), ADHD, and comorbid ADHD and RD (ADHD + RD). Children's EF and reading skills were measured. Analysis of variance results showed that all children with disorders manifested deficits in verbal and visuospatial short-term and working memory and behavioral inhibition. Moreover, children with ADHD and ADHD + RD also exhibited deficits in inhibition (IC and BI) and cognitive flexibility. These findings demonstrated that the EF deficits in Chinese children with RD, ADHD, and ADHD + RD are similar to those in their counterparts using alphabetic languages. However, children with ADHD + RD displayed more severe deficits in visuospatial working memory compared to children with RD and ADHD, which was inconsistent with that observed in children using alphabetic languages. Regression analysis results showed that verbal short-term memory was a significant predictor for both word reading and reading fluency in children with RD and ADHD + RD. Moreover, behavioral inhibition significantly predicted reading fluency in children with ADHD. These findings also agreed with previous studies. Collectively, the results of the current study showed that the EF deficits and their roles in reading found in Chinese children with RD, ADHD, and ADHD + RD are mainly consistent with children using alphabetic languages. However, more studies are still needed to confirm these findings, especially comparing the severity of working memory among these three disorders.