This study investigates the functional connectivity between the dorsal anterior cingulate cortex (dACC) and the default-mode network in adults with Attention-Deficit/Hyperactivity Disorder (ADHD). The authors hypothesized that abnormalities in these circuits, which are involved in preventing attentional lapses, might contribute to ADHD. Using resting-state functional MRI (fMRI), they found that individuals with ADHD showed significantly reduced functional connectivity between the dACC and posterior components of the default-mode network, including the precuneus and posterior cingulate cortex (PCC). Secondary analyses revealed additional decreases in connectivity within the default-mode network, particularly between the precuneus/PCC and ventromedial prefrontal cortex. These findings suggest that the long-range connections linking the dACC to the precuneus and PCC may be a key locus of dysfunction in ADHD, complementing previous anatomical evidence of posterior volumetric abnormalities. The study also highlights the importance of examining functional connectivity in ADHD, particularly in regions involved in attentional control and default-mode network regulation.This study investigates the functional connectivity between the dorsal anterior cingulate cortex (dACC) and the default-mode network in adults with Attention-Deficit/Hyperactivity Disorder (ADHD). The authors hypothesized that abnormalities in these circuits, which are involved in preventing attentional lapses, might contribute to ADHD. Using resting-state functional MRI (fMRI), they found that individuals with ADHD showed significantly reduced functional connectivity between the dACC and posterior components of the default-mode network, including the precuneus and posterior cingulate cortex (PCC). Secondary analyses revealed additional decreases in connectivity within the default-mode network, particularly between the precuneus/PCC and ventromedial prefrontal cortex. These findings suggest that the long-range connections linking the dACC to the precuneus and PCC may be a key locus of dysfunction in ADHD, complementing previous anatomical evidence of posterior volumetric abnormalities. The study also highlights the importance of examining functional connectivity in ADHD, particularly in regions involved in attentional control and default-mode network regulation.