Comorbidity of reading disabilities and ADHD: Structural and functional brain characteristics

Abstract

Reading disabilities (RD) and attention‐deficit/hyperactivity disorder (ADHD) are two of the most common developmental disorders. RD and ADHD frequently co‐occur, which raises questions about how the disorders interact and to what extent they can be differentiated. To date, the underlying neural mechanisms leading to RD–ADHD comorbidity (COM) are not understood. In this study, structural and functional magnetic resonance imaging (fMRI) were combined with comprehensive behavioral testing in order to characterize the behavior, brain structure, and neural correlates of executive function, phonological processing and reading fluency in 60 children with clinical diagnoses of RD, ADHD, or COM, and controls. Whole‐brain analyses of variance were performed on cortical thickness values and on the data of the three fMRI tasks to investigate overall group differences. To validate these findings, a region of interest analysis was performed in regions that have previously been shown to exhibit group differences in children with RD or ADHD using the same paradigms. The neuroimaging results demonstrated structural and functional atypicalities for COM in regions that are frequently associated with deficits in children with isolated ADHD or RD. A combination of shared and distinctive brain alterations between the clinical groups was identified, supporting the multiple deficit model for ADHD, RD, and its comorbidity.

Visual Search in Chinese Children With Attention Deficit/Hyperactivity Disorder and Comorbid Developmental Dyslexia: Evidence for Pathogenesis From Eye Movements

“…Therefore, the present study provides evidence for the shared cognitive deficit model in the early processing stage and for the distinguished cognitive deficit model in the late processing stage. We agree that a single model was not enough to explain the causes of comorbid DD and ADHD ( Pennington, 2006 ; Willcutt et al, 2010 ), and multiple models may apply to different processing stages ( Langer et al, 2019 ). The findings of the current study are important for the contribution to investigate visual search and lexical processing in clinical groups like comorbidity of ADHD and other disabilities, showing eye-movement measures may be helpful in the diagnostic procedure of comorbidity in the future.…”

Putative protective neural mechanisms in prereaders with a family history of dyslexia who subsequently develop typical reading skills

“…The experimental and the control tasks were administered in separate runs, as an initial pilot study showed that the youngest participants (62.2–81.6 months) confused the two tasks when they were interleaving within the same run (Raschle, Zuk, Ortiz‐Mantilla, et al, ). This task has been used by our group numerous times (e.g., Langer, Benjamin, Becker, & Gaab, ; Powers, Wang, Beach, Sideridis, & Gaab, ; Raschle et al, , ; Yu et al, , Zuk et al, ), and several other studies have adapted this design for young pediatric populations (e.g., Dębska et al, , ). The order of the two runs was counterbalanced across participants (see more details in Raschle et al, , ).…”

Pediatric ADHD symptom burden relates to distinct neural activity across executive function domains

“…This symptom burden can impact cognitive, academic, and social-emotional processes ( Chacko et al, 2014 , Cortese, 2012 , Nigg et al, 2005 , Voeller, 2004 ). ADHD is highly comorbid with learning difficulties ( Langer et al, 2019 ; Willcutt et al, 2010 ), and some individuals with ADHD have impairments in executive functions (EFs) ( Biederman, 2003 , Kofler et al, 2018 , Nigg et al, 2005 , Roberts et al, 2017 ). EFs support goal-oriented behaviors and comprise regulatory processes across several domains such as cognitive flexibility, working memory, and inhibition ( Diamond, 2013 , Miyake and Friedman, 2012 ) and are vital in the transition from immature to mature cognition and behaviors ( Diamond, 2013 , Miyake and Friedman, 2012 ).…”