Mediating impact of intranasal oxytocin on the interaction between irritability and reactive aggression in youth with severe irritability

Objective: Irritability and reactive aggression are transdiagnostic features that are predictive of adverse long-term outcomes. This investigation examined whether intranasal oxytocin administration impacts the interaction between irritability and reactive aggression, and whether these effects can be detected at a neural level via a facial expression processing task during functional MRI (fMRI). Methods: In this study, 40 children and adolescents with severe irritability and psychiatric diagnoses of disruptive mood and behavioral disorders were assigned to either intranasal oxytocin or placebo administration over a 3-week period in a randomized, double-blind trial (ClinicalTrials, NCT02824627). Clinical measures and fMRI during a facial expression processing task were collected pre- and post-intervention. Brain regions sensitive to oxytocin administration were determined using whole-brain statistical analyses, with post hoc analyses to determine whether changes in the neural activity mediated the relationship between changes in irritability and reactive aggression across the intervention period. Results: Youth who received intranasal oxytocin administration exhibited significant decreases in irritability and reactive aggression compared to their counterparts in the placebo group. Further, oxytocin administration was associated with significant increases in neural activity in the right superior prefrontal cortex, which fully mediated the relationship between improvements in irritability and improvements in reactive aggression. Conclusions: Intranasal oxytocin significantly reduced irritability and reactive aggression in youth, as well as neural activity in the prefrontal cortex, such that increases in the cortical activity fully mediated the relationship between changes in irritability and reactive aggression. Taken together, these findings may reflect oxytocin-related enhancements in emotional regulation in youth with severe irritability, a potential therapeutic mechanism for mitigating reactive aggression.