Are “cool” executive function impairments more salient in ADHD symptoms than in reading disability?

ABSTRACT Introduction: Reading disability (RD) and Attention Deficit Hyperactivity Disorder (ADHD) symptoms often co-occur in school-age children. Methods: The present study evaluated the performance of 216 Brazilian children from 3rd and 4th grades on “cool” executive function (EF) abilities and phonological processing. The children were divided into three groups: those with ADHD symptoms only, those with RD only, and controls. Results: MANOVA analyses, controlling for age and nonverbal intelligence, showed worse performance for the RD group, compared to the ADHD symptoms group, on measures of phonological processing (phonemic awareness, phonological short-term memory, and lexical access) and “cool” EF components (orthographic verbal fluency and processing speed). The ADHD symptoms group did not differ from the control group on the majority of the “cool” EF tasks. Compared to the control group, the ADHD symptoms group and the RD group both showed significantly more errors in rapid automatized naming of figures, which evaluates the inhibition component of EF; performance on this task was similar for these groups. Conclusion: We conclude that children with RD have greater impairment in phonological processing and “cool” EF compared to those with ADHD symptoms. Furthermore, deficits in inhibitory control may be shared among children with both conditions.

摘要
引言：阅读障碍（Reading Disability, RD）与注意缺陷多动障碍（Attention Deficit Hyperactivity Disorder, ADHD）症状常共现于学龄儿童群体中。
方法：本研究对216名巴西三、四年级儿童的「冷」执行功能（Executive Function, EF）能力与语音加工（phonological processing）能力开展表现评估。研究对象被划分为三组：仅伴ADHD症状组、仅伴阅读障碍组，以及健康对照组。
结果：在控制年龄与非语言智力变量后，多变量方差分析（MANOVA）结果显示，相较于仅伴ADHD症状组，仅伴阅读障碍组在语音加工任务（语音意识（phonemic awareness）、语音短时记忆（phonological short-term memory）与词汇通达（lexical access））及「冷」执行功能维度（正字法言语流畅度（orthographic verbal fluency）与加工速度（processing speed））上的表现更差。仅伴ADHD症状组在多数「冷」执行功能任务中的表现与健康对照组无显著差异。相较于健康对照组，仅伴ADHD症状组与仅伴阅读障碍组在图形快速自动化命名（rapid automatized naming）任务中的错误率均显著更高——该任务用于评估执行功能的抑制控制成分（inhibition component of EF），且两组在此任务上的表现无显著差异。
结论：本研究表明，相较于仅伴ADHD症状的儿童，阅读障碍儿童在语音加工与「冷」执行功能方面的损伤程度更为严重。此外，两类患儿可能共享抑制控制相关的功能缺陷。