Current etiological mechanisms of Attention-Deficit/Hyperactivity Disorder (ADHD) suggest alterations in the development of prefrontal-striatal-cerebellar networks. Presently it is unclear what relates to the alterations in cortical and subcortical development and thus symptoms of ADHD. Recent studies found reduced cortical thickness and surface area in children with ADHD who have been successfully treated with psychostimulant medication for an extended period of time compared to children with ADHD who have not taken psychostimulants, suggesting therapeutic psychostimulant use may alter trajectories in brain development in ADHD. It is unclear whether these changes in cortical morphology are associated with normalized behavioral outcomes or if changes in cortical morphology predict negative behavioral outcomes. Thus, the purpose of the current study was three-fold: 1) The current study implemented advanced surface-based cortical neuroimaging techniques to determine if cortical thickness differed between children with ADHD compared to typically-developing controls, 2) the study compared cortical thickness in children with ADHD who had been chronically-treated with psychostimulant medication (methylphenidate), children with ADHD who had never received medication, and typically-developing controls, and 3) the study also investigated the relationship between cortical thickness and behavioral and neuropsychological outcomes. The main findings from the current study included significant cortical thinning of the right rostral ACC but non-significant thinning in any region of the prefrontal cortex (PFC) or parietal cortex. It was also found that medication history did not affect cortical thickness measures. Treated and Not-Treated ADHD groups had reduced cortical thinning in the right rostral ACC with the Treated group (p = .043) only slightly different from controls compared to the Not-Treated ADHD group (p = .017). Lastly, right rostral ACC thickness predicted a significant amount of the variance in parent and teacher reported symptoms of ADHD. No such relationship emerged between cortical thickness and response inhibition neuropsychological measures. Results of this study are among the first to suggest brain-behavior relationships between ADHD symptoms and regional cortical thickness measures. Furthermore, it is likely that brain morphological differences related to long-term psychostimulant use may depend on both the age of the child and the duration of treatment with psychostimulants.
Read
