Project Summary Attention-deficit hyperactivity disorder (ADHD) is prevalent during early and middle childhood, causing substantial disruptions to everyday life of afflicted children, along with their peers and parents. While primarily recognized as an executive functioning disorder, there are substantial social-cognitive deficits in youth with ADHD that can further disrupt the child's development in key areas such as empathy, emotion recognition, and theory of mind. These impairments are often exacerbated in youth with ADHD and comorbid oppositional defiant disorder (ODD), who demonstrate a variety of defiant, aggressive, and hostile behaviors. The degree to which social-cognitive deficits in youth with ADHD represent a distinct impairment is unclear: an inability to attend to social cues may drive deficits in social cognition. While attention problems are related to social deficits, we do not know whether executive dysfunction is specifically driving social cognition problems. Moreover, while neuroimaging research of ADHD has largely revealed prefrontal dysfunction and delayed white matter maturation, very little research has examined brain function during social cognitive processing. To fill these research gaps, this investigation will employ virtual reality (VR) and neuroimaging with three matched groups of youth in middle childhood (ages 9-12): typical developing youth, youth with ADHD but no comorbid ODD (ADHD-ODD), and youth with ADHD and comorbid ODD (ADHD+ODD). We will build upon our ongoing VR and neuroimaging research to examine how removing background audio and visual stimuli in realistic scenes modifies social cognitive skills in youth with ADHD. We will measure empathy, hostility biases, and emotion recognition during virtual scenes with distinct levels of audiovisual background stimuli that may draw attention away from social cues. Subsequently, during fMRI, we will examine how social brain circuitry is impacted by the removal of visual distracters during empathic decision making. With this design, we strive to achieve the following specific aims: to examine whether decreasing background distractions in a naturalistic virtual environment is related to social cognition in youth with ADHD-ODD and ADHD+ODD (Aim 1); and to characterize, in youth with ADHD-ODD and ADHD+ODD, how brain mechanisms underlying empathic decision making are impacted by visual interference and how white matter microstructure is associated with cognitive and emotional empathy (Aim 2). We hypothesize that decreasing levels of background audiovisual stimuli will improve attention to social cues in youth with ADHD, improving measures of social cognition and engagement of social brain regions in both youth with ADHD-ODD and ADHD+ODD. This would indicate that an inability to properly attend to social cues is driving social cognition deficits. However, if attention deficits are not driving social impairments in youth with ADHD+ODD, removing distracters will have littl...