Discrete components of stress impact trajectories of childhood irritability but not adolescent mental health outcomes.

Background: Exposure to stressors during early childhood has been linked to irritability and subsequent mental health problems; however, little work has examined the unique and combined effects of distinct stress exposures on trajectories of childhood irritability or adolescent mental health symptoms. Methods: Six components of family stress were assessed via maternal report at child age 5. Irritability was measured longitudinally at ages 7, 9, and 11. Adolescents self-reported on anxiety, depression, and externalizing symptoms at age 13-20. Latent growth mixture modeling examined classes of irritability. Bayesian kernel machine regression (BKMR) examined unique and shared effects of stress components on class assignment and to continuously measured irritability at individual age points ( Results: Latent growth mixture modeling identified high and low irritability classes. A positive joint mixture effect of stressors on irritability was detected, with additive contributions from intimate partner violence, material hardship, perceived stress, and maternal demoralization. Intimate partner violence independently predicted high irritability over time and irritability at age 7, and maternal perceived stress independently predicted irritability at age 11. Neither childhood irritability nor early stress predicted self-reported adolescent mental health symptoms. Conclusion: Early exposure to familial stressors are risk markers for childhood irritability. Interventions targeting intimate partner violence and co-occurring stressors could help mitigate persistent irritability, a well-known public health concern related to children's development.