Cross-Sectional and Longitudinal Relations Among Irritability, Attention-Deficit/Hyperactivity Disorder Symptoms, and Inhibitory Control

OBJECTIVE:Irritability and attention-deficit/hyperactivity disorder (ADHD) symptoms frequently co-occur in youth. While ADHD has been associated with inhibitory control deficits, the literature on irritability and inhibitory control is mixed. Examining how irritability, ADHD symptoms, and inhibitory control interrelate both cross-sectionally and longitudinally across development could shed light on common and distinct mechanisms of youth psychopathology. METHOD:We utilized a cross-lagged panel model with data from two time points (at ages 10 and 12 years) of the Adolescent Brain and Cognitive Development (ABCD) Study (N = 7,444, or ∼63% of the baseline sample with full data at each time point) to test cross-sectional and longitudinal associations among parent-reported irritability and ADHD symptoms and behaviorally-assessed inhibitory control. This was performed separately across discovery and replication subsamples, each n = 3,722. RESULTS:As expected, irritability and ADHD symptoms exhibited strong cross-sectional and reciprocal cross-lagged associations. Higher ADHD symptoms at age 10 were associated concurrently with poorer inhibitory control and predicted poorer inhibitory control at age 12. Contrary to predictions, inhibitory control was not significantly associated with irritability cross-sectionally nor predictive of later irritability or ADHD symptoms. CONCLUSION:These findings highlight strong links between irritability and ADHD. While inhibitory control deficits were linked to ADHD and predictive of its symptom course, it had no significant associations with irritability. Future research should investigate other candidate mechanisms of the co-occurrence of irritability and ADHD symptoms and predictors of their developmental trajectories.