Navigating Complex Family and Social Support Systems Following an Agricultural Injury: A Qualitative Study of the True Burden of Injury.

Attention-deficit/hyperactivity disorder (ADHD) is the most common neurodevelopmental disorder of childhood, affecting 8% to 10% of school-age children. The clinical presentation of ADHD evolves across the lifespan, with variable patterns of symptom persistence and remission, although significant functional impairment is generally present into adolescence and adulthood. Importantly, there is mounting evidence that females diagnosed with ADHD in childhood are at increased risk for negative outcomes in adolescence and adulthood than males. Despite this, research on ADHD has predominantly focused on males because of initial prevalence data reporting sex ratios (M:F) ranging from 4:1 to 9:1, although more recent estimates among community samples suggest a lower sex disproportion of 2:1. Thus, there is limited understanding of the impact of sex on clinical trajectories given the focus on males, including symptom progression and functional outcomes; to our knowledge, no studies have reported the brain basis for sex differences in symptom expression across child to adolescent development. There is increasing evidence of sex differences in children with ADHD at the brain, behavioral, and clinical levels. Published findings suggest a pattern of sex-based distinctions in neurobehavioral features in prepubertal children (aged 8–12 years) with ADHD regarding brain structure, functional connectivity, expressed behavioral patterns of inhibition, and response to reward. Specifically, males with ADHD show abnormalities in premotor basal ganglia circuits with impaired motor inhibition; on the other hand, females with ADHD show abnormalities in prefrontal and limbic circuits with heightened delay discounting (i.e. a stronger preference for smaller, immediate rewards over larger, delayed rewards). ADHD-related sex differences in brain and behavior in childhood may represent neurobehavioral risk phenotypes for poor outcomes in adolescence. However, we are unaware of any research that has examined childhood neurobehavioral predictors of clinical symptom trajectories in females and males with ADHD as they transition into adolescence. Anomalous white matter organization, assessed with diffusion magnetic resonance imaging (dMRI), has been implicated in the pathophysiology of ADHD. A recent review of dMRI studies in young people with ADHD (aged 3–18 years) showed reduced fractional anisotropy, which is thought to reflect the strength of the white matter connections in the brain, in young people with ADHD. This was observed in several brain regions, with the most consistent findings in the frontostriatal tracts, corpus callosum, and superior longitudinal fasciculus. However, findings in the ADHD literature are inconsistent, probably because of potential confounders such as head motion, imbalanced sex distribution in the study samples, and the predominant use of diffusion tensor imaging to model white matter organization. Regarding the latter, diffusion tensor imaging is unable to reconcile complex (i.e. multiple) fiber orientations in a given voxel. This has led to criticism about the biological plausibility of diffusion tensor imaging-derived tractography, and the specificity of the quantitative metrics (e.g. fractional anisotropy) derived from the tensor model for inferring the microstructural and macrostructural properties of tracts.