Joint Developmental Trajectories of Irritability and Executive Function: Associations with Time-varying...

Existing research has established that irritability and executive function (EF) are distinct yet often co-occurring transdiagnostic symptoms, each with its developmental trajectory. However, no evidence exists on whether these two symptoms follow joint developmental patterns or on which patterns increase risk for later problems. To address this gap, the present study tracked joint trajectories of irritability and EF and linked these patterns to subsequent externalizing and internalizing problems. A seven-wave longitudinal design was employed with a sample of 491 students in China (M_age = 9.84 years, SD = 0.71; 48.1% boys). Irritability was reported by mothers, while adolescents completed three EF tasks assessing inhibitory control, working memory, and cognitive flexibility and reported their own psychopathological problems. Parallel Process Latent Growth Curve Modeling was used to examine joint trajectories of irritability and EF. BCH auxiliary analysis was conducted to test whether externalizing and internalizing problems differed across the identified classes. Four joint irritability-EF trajectories emerged: Persistently High Irritability, Low-Increasing EF, Adapted, and Moderate. The Persistently High Irritability class exhibited the highest externalizing problems, followed by the Low-Increasing EF class, a pattern that remained robust after multiple comparison correction. The Adapted class exhibited relatively high levels of both externalizing and internalizing problems, a pattern that did not remain robust after multiple comparison correction. These findings highlight the co-occurrence and diversity of developmental patterns of irritability and EF, with distinct patterns conferring specific risks for later externalizing versus internalizing problems, underscoring the importance of early identification of at-risk trajectories for targeted intervention.