Inattention and hyperactivity predict alterations in specific neural circuits among 6-year-old boys.

Objective: Assessment of inattention and hyperactivity in preschoolers is highly dependent upon parental reports. Such reports are compromised by parental attitudes and mental health. Our study aimed to examine associations of inattention and hyperactivity/impulsivity from maternal reports on the Conners' Parent Rating Scale (CPRS) with brain morphology assessed using structural magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) in 6-year-old boys.

Method: Large deformation diffeomorphic metric brain mapping was used to assess brain morphology on MRI and DTI in 96 six-year-old boys, including cortical thickness, subcortical shapes, and fractional anisotropy (FA) of deep white matter tracts (DWMTs). Linear regression examined associations between these measures of brain structures and mothers' CPRS ratings of their child's inattention and hyperactivity/impulsivity.

Results: Our results revealed that temporal and parietal cortices, as well as posterior white matter and callosal tracts are associated with inattention and hyperactivity/impulsivity symptoms among six-year-old boys. Inattention and hyperactivity/impulsivity symptoms share common neural circuits, but hyperactivity/impulsivity ratings associate with more extensive cortical areas, such as frontal regions, and with white matter tracts emphasizing executive control. There were no associations detected between inattention (or hyperactivity/impulsivity) and the shape of subcortical structures.

Conclusions: Our results suggested specific rather than widespread neural circuits involved in inattention and hyperactivity/impulsivity in young children, which is congruent with existing findings in older children and adolescents, and in adults with attention-deficit/hyperactivity disorder (ADHD). Hence, our study supported the dimensional view of ADHD, that is, that symptoms of inattention and hyperactivity/impulsivity lie on a continuum.