Reconfiguration of functional brain network organization and dynamics with changing cognitive demands in children with attention-deficit/hyperactivity disorder.

Background: The pathophysiology of attention-deficit/hyperactivity disorder (ADHD) is characterized by atypical brain network organization and dynamics. Although functional brain networks adaptively reconfigure across cognitive contexts, previous studies have largely focused on network dysfunction during the resting-state. This preliminary study examined how functional brain network organization and dynamics flexibly reconfigure across rest and two cognitive control tasks with different cognitive demands in 30 children with ADHD and 36 typically developing (TD) children (8-12 years).

Methods: We leveraged graph theoretical analyses to interrogate the segregation (modularity, within-module degree) and integration (global efficiency, node dissociation index) of fronto-parietal, cingulo-opercular/salience, default mode, somatomotor, and visual networks. We also conducted edge timeseries analyses to quantify connectivity dynamics within and between these networks.

Results: Across resting and task-based states, children with ADHD demonstrated significantly lower whole-graph modularity and greater node dissociation index between default mode and visual networks. Further, a significant task-by-diagnosis interaction was observed for fronto-parietal network within-module degree, which decreased from rest to task in children with ADHD but increased in TD children. Finally, children with ADHD displayed significantly more dynamic connectivity within and across cingulo-opercular/salience, default mode, and somatomotor networks, especially during task performance. Exploratory analyses revealed associations between network dynamics, cognitive performance, and ADHD symptoms.

Conclusions: By integrating static and dynamic network analyses across changing cognitive demands, this study provides novel insight into how context-specific, context-general, and timescale-dependent network connectivity is altered in children with ADHD. Our findings highlight the involvement and clinical relevance of both association and sensory/motor systems in ADHD.