Abnormalities in cortical surface area and thickness among children with attention-deficit/hyperactivity disorder (ADHD) were not observed in adolescents or adults, according to study data published in the American Journal of Psychiatry.
Investigators abstracted data from the ENIGMA-ADHD Working Group, the NeuroIMAGE study, and the Generation-R sample. The ENIGMA-ADHD Working Group comprises structural imaging data for patients with ADHD from 36 centers around the world. Many ENIGMA centers also include data from healthy control patients. Cortical thickness and surface area were compared between patients with ADHD (n=2246) and patients without ADHD (n=1934) from the ENIGMA-ADHD cohorts. Children, adolescents, and adults were assessed separately. The NeuroIMAGE study, a subset of the ENIGMA-ADHD sample, also collected imaging data from patients (n=211) and their unaffected siblings (n=175), as well as from unrelated patients (n=120). Cortical differences between latter 2 groups were assessed. In addition, associations between these cortical measures and attention problems, as determined from the Child Behavior Checklist, were assessed in Generation-R, an independent pediatric cohort of patients with ADHD (n=2707).
Compared with members of the control group in the same age range, children (<14 years) with ADHD had lower cortical surface area in 24 of 34 analyzed regions and smaller total surface area. Effect sizes were most pronounced for total surface area, the superior frontal gyrus, and the lateral orbitofrontal cortex (all P <.001). The youngest subgroup (ages 4-9 years) had the largest case-control differences in surface area. Cortical thickness was thinner among children with ADHD for the fusiform gyrus, parahippocampal gyrus, precentral gyrus, and temporal pole (all P <.001). No case-control differences in cortical area or thickness were observed for the adolescent and adult groups. Per NeuroIMAGE data, total surface area (P =.003) and surface area of the caudal middle frontal (P =.0001), lateral orbitofrontal (P =.002), and superior frontal gyrus (P =.0004) were significantly smaller in unaffected siblings compared with control group members. Such results suggest familial effects of ADHD. Finally, a greater score on the attention problems scale of the Child Behavior Checklist was associated with smaller total surface area (P <.001) and smaller surface area in the caudal middle frontal gyrus (P =.01) and the middle temporal gyrus (P =.02).
These data identify a set of cortical “phenotypes” associated with ADHD and support a familial effect of the condition on cortical thickness. Investigators noted that cortical alterations behaved similar to endophenotypes within families, supporting the theory that ADHD behaves as a continuous trait in the population. Further longitudinal studies are necessary to explore lifespan trajectories that lead to nonsignificant findings in adolescent and adult groups.
Hoogman M, Muetzel R, Guimaraes JP, et al. Brain imaging of the cortex in ADHD: a coordinated analysis of large-scale clinical and population-based samples [published online April 24, 2019]. Am J Psychiatry. doi:10.1176/appi.ajp.2019.18091033