Differences in functional activity between boys with pure oppositional defiant disorder and controls during a...

Functional Magnetic Resonance Imaging (fMRI) of inhibitory control has only been investigated in patients with attention deficit hyperactivity disorder (ADHD) and conduct disorder (CD). The objective of this study was to investigate the differences of functional areas associated with inhibitory control between boys with pure oppositional defiant disorder (ODD) and controls during a response inhibition task using functional magnetic resonance imaging (fMRI). Eleven boys with pure ODD and ten control boys, aged 10 to 12, performed a GoStop response inhibition task in this study. The task has a series of "go" trials to establish a pre-potent response tendency and a number of "stop" trials to test subjects' ability to withhold their responses. During the GoStop task, greater activation in the dorsolateral parts of the bilateral inferior frontal gyrus, left middle frontal gyrus (lMFG) and right superior frontal gyrus (rSFG) activation was seen in the ODD boys. Additionally, reduced activation in regions of the right inferior frontal gyrus (rIFG) was seen in the ODD boys in comparison with the control group. The results may suggest that the higher activation in areas adjacent to the rIFG could be the cause of reduced activation in the rIFG; although this is speculative and requires additional supporting evidence. The findings further suggest that ODD is a less pronounced functional disorder compared to ADHD and CD.