Interference of default mode on attention networks in adults with attention‐deficit/hyperactivity disorder and its association with genetic variants and treatment outcomes

Aims Altered brain functional connectivity has been proposed as the neurobiological underpinnings of attention‐deficit/hyperactivity disorder (ADHD), and the default mode interference hypothesis is one of the most popular neuropsychological models. Here, we explored whether this hypothesis is supported in adults with ADHD and the association with high‐risk genetic variants and treatment outcomes. Methods Voxel‐based whole‐brain connectome analysis was conducted on resting‐state functional MRI data from 84 adults with ADHD and 89 healthy controls to identify functional connectivity substrates corresponding to ADHD‐related alterations. The candidate genetic variants and 12‐week cognitive behavioral therapy data were leveraged from the same population to assess these associations. Results We detected breakdowns of functional connectivity in the precuneus and left middle temporal gyrus in adults with ADHD, with exact contributions from decreased connectivity within the default mode, dorsal and ventral attention networks, as well as increased connectivity among them with the middle temporal gyrus serving as a crucial ‘bridge’. Additionally, significant associations between the altered functional connectivity and genetic variants in both MAOA and MAOB were detected. Treatment restored brain function, with the amelioration of connectivity of the middle temporal gyrus, accompanied by improvements in ADHD core symptoms. Conclusions These findings support the interference of default mode on attention in adults with ADHD and its association with genetic risk variants and clinical management, providing insights into the underlying pathogenesis of ADHD and potential biomarkers for treatment evaluation. Our voxel‐based connectome analyses indicated hypoconnectivity within the DMN (the connectivity between the precuneus with other DMN components) and attentional networks (the connectivity between the left middle temporal cluster and other DAN/VAN components) and hyperconnectivity between these networks (the connectivity between the left middle temporal and DMN components) in adults with ADHD, with the middle temporal gyrus as a key ‘bridge’ region.