Distinct patterns of cortical thinning in concurrent motor and attention disorders

Aim Many neurodevelopmental disorders co‐occur yet are rarely studied in terms of brain development. Developmental coordination disorder (DCD) and attention‐deficit–hyperactivity disorder (ADHD) co‐occur at a high frequency and are associated with functional and structural brain alterations. The objective of this study was to examine whether the effects of comorbid motor and attention problems influence cortical thickness in children and whether the pattern of changes for concurrent disorders is distinct from the alterations seen in single disorders. Method A total of 34 children (19 males, 15 females, mean age 9y 9mo, range 8–17y) who met the criteria for DCD (n=14), ADHD (n=10), or DCD+ADHD (n=10) were recruited into the study. Fourteen participants with typical development (eight males, six females, mean age 11y 9mo, range 8–17y) were also recruited for comparison. Participants underwent neuropsychological assessment and magnetic resonance imaging. Cortical thickness analysis was performed to determine the patterns of cortical thinning in each disorder, which was then compared across groups. Results Children with comorbid DCD+ADHD demonstrated more widespread decreases in cortical thickness than participants with a diagnosis of DCD or ADHD alone. Cortical thinning was found to be concentrated in the frontal, parietal, and temporal lobes, and was correlated with measures of motor and attentional functioning. Interpretation The co‐occurrence of DCD+ADHD was associated with a distinct global pattern of regional cortical thickness decrease, highlighting the unique neurobiology of comorbid neurodevelopmental disorders. This novel feature of concurrent DCD and ADHD may help inform diagnostic definitions and provide clues to both the shared and the isolated genetic and environmental origins of motor and attention disorders. What this paper adds We examined children with single and comorbid motor and attention issues for cortical thickness differences. In participants with ADHD alone, thickness reductions were found in the left superior temporal gyrus and parahippocampal gyrus. In participants with DCD alone, cortical thickness reductions were found in the medial orbitofrontal cortex. In comorbid DCD+ADHD, global cortical thinning deficits were found in the frontotemporal, parietal, and occipital regions Concurrent DCD+ADHD correlated with poorer motor and attentional performance. This article is commented on by Brossard‐Racine on pages 211–212 of this issue.