ADHD and PBD are two developmental syndromes with high comorbidity rates and common symptoms of inattention, impulsivity and hyperactivity.

Mechanistic comprehension of neural circuitry function will enhance our understanding of the dimensional functions of affect and cognition, and guide rational pharmacological treatment for ADHD and PBD.

The aim of this research is to further examine the neural bases of impulsivity in distributed brain networks engaged during execution or inhibition of a pre-potent motor response in adolescents with PBD and ADHD relative to healthy controls (HC).

31 adolescents with PBD, 24 PBD/ADHD, 22 ADHD and 33 HC (mean age 13.78 ± 2.4), underwent fMRI stop signal task, examining the ability to inhibit a prepotent motor response.

Relative to HC, ADHD showed greater connectivity in bilateral cerebellum and decreased connectivity in left precuneus and subgenual ACC (Figure 1, Panel A). The PBD/ADHD group's functional connectivity was reduced in limbic regions relative to the other three groups, while it was increased in right insula relative to ADHD (Figure 1, Panel B).

Findings suggest that within an attentional control network relative to HC, both PBD and ADHD groups exhibit greater functional connectivity in right VLPFC. The PBD/ADHD group showed more severe PBD-like pattern of over-engagement in emotional regions, and a less severe ADHD-like pattern in posterior attentional regions. Figure 1:

During Behavior Inhibition