Attention-deficit/hyperactivity disorder is characterized by a delay in cortical maturation

TLDR

ADHD’s underlying brain development disturbance is debated, with uncertainty whether it reflects a delay in maturation or a distinct developmental trajectory. Using high‑resolution cortical thickness mapping from 824 MRI scans of 223 ADHD and 223 controls, the authors modeled quadratic growth trajectories to estimate the age of peak thickness as a maturation index. They found that although regional maturation patterns were similar, ADHD children exhibited a significant delay in reaching peak cortical thickness—median 10.5 versus 7.5 years—especially in prefrontal areas, marking the first neuroanatomic evidence of such a delay.

Abstract

There is controversy over the nature of the disturbance in brain development that underpins attention-deficit/hyperactivity disorder (ADHD). In particular, it is unclear whether the disorder results from a delay in brain maturation or whether it represents a complete deviation from the template of typical development. Using computational neuroanatomic techniques, we estimated cortical thickness at >40,000 cerebral points from 824 magnetic resonance scans acquired prospectively on 223 children with ADHD and 223 typically developing controls. With this sample size, we could define the growth trajectory of each cortical point, delineating a phase of childhood increase followed by adolescent decrease in cortical thickness (a quadratic growth model). From these trajectories, the age of attaining peak cortical thickness was derived and used as an index of cortical maturation. We found maturation to progress in a similar manner regionally in both children with and without ADHD, with primary sensory areas attaining peak cortical thickness before polymodal, high-order association areas. However, there was a marked delay in ADHD in attaining peak thickness throughout most of the cerebrum: the median age by which 50% of the cortical points attained peak thickness for this group was 10.5 years (SE 0.01), which was significantly later than the median age of 7.5 years (SE 0.02) for typically developing controls (log rank test chi(1)(2) = 5,609, P < 1.0 x 10(-20)). The delay was most prominent in prefrontal regions important for control of cognitive processes including attention and motor planning. Neuroanatomic documentation of a delay in regional cortical maturation in ADHD has not been previously reported.