The Impact of Irritability and Callous Unemotional Traits on Reward Positivity in Youth with ADHD and Conduct Problems.

Children with attention-deficit/hyperactivity disorder (ADHD) and conduct problems exhibit significant variability in functioning and treatment response that cannot be fully accounted for by differences in symptom severity. Reward responsivity (RR) is a potential transdiagnostic means to account for this variability. Irritability and callous-unemotional (CU) traits moderate associations between both ADHD and conduct problems with multiple realms of functioning. Both are theorized to be associated with RR, but associations in clinical samples are unknown. In 48 youth ages 5-12 with ADHD referred for treatment of conduct problems, we examined RR using a guessing task where participants select a door icon to win and lose money. Analyses focused on the reward positivity (RewP) event-related potential in response to gain and loss feedback, which reliably peaks approximately 300 ms after feedback. Frequentist and Bayesian approaches assessed main effects of ADHD, Conduct Disorder (CD) and non-irritable Oppositional Defiant Disorder (ODD) symptoms with RR, plus interactions between symptoms and affective dimensions (irritability, CU). CD and ODD were hypothesized to be associated with altered RR, with irritability and CU moderating these associations. Across models, a reliable CD x irritability interaction emerged, indicating enhanced RewP when irritability was elevated and CD symptoms were low. CU did not moderate any associations with RR, and little support was found for associations between RR and other symptom domains. As neural response to reward varied with levels of irritability and CD symptoms, RR may hold potential as a clinically-relevant biomarker in youth with ADHD and conduct problems.