Altered stability of dynamic functional architecture in the co-occurrence of autism spectrum disorder and attention-deficit/hyperactivity disorder

Autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD) frequently co-occur, whereas the underlying neurobiological mechanisms remain largely unexplored. This study aimed to identify alterations in dynamic functional architecture across ASD, ADHD, and their comorbidity. This study selected 287 participants from the Autism Brain Imaging Data Exchange and ADHD-200 datasets, divided into ASD without ADHD (ASD-only), ADHD without ASD (ADHD-only), ASD + ADHD, and typically developing (TD) groups. In this study, we employed dynamic functional stability at the voxel level by measuring the temporal concordance of dynamic functional connectivity (DFC). Furthermore, whole-brain DFC analyses were conducted using clusters with significant stability alterations as seed regions. Group comparisons and correlation analyses were subsequently performed. Our results showed significant group differences in functional stability in the left superior frontal gyrus, orbital part (ORBsup), right pallidum, and left amygdala. Seed-based analyses identified altered DFC variability between the left amygdala and three regions, including the right middle temporal gyrus (MTG), the left insula, and the left superior occipital gyrus (SOG). Notably, DFC variability between the left amygdala and right MTG was significantly negatively correlated with Social Communication Questionnaire (SCQ) scores in the comorbidity group (r = - 0.620, p < 0.01, FDR corrected). From a dynamic perspective, our findings revealed that ASD, ADHD, and their comorbidity exhibited commonanduniquechanges in brain function, thereby enhancing our understanding of the pathogenesis underlying ASD + ADHD.