Using a Developmental Approach to Investigate Behavioral, Neurodevelopmental, and Depressive Irritability Types

Objective: , as depressive (core to disruptive mood dysregulation disorder). Irritability is also highly prevalent in, and genetically linked to, neurodevelopmental conditions. It is unclear whether irritability represents a unitary construct or multiple different types. We examined whether distinct behavioral, neurodevelopmental, and depressive irritability types, differentiated by their developmental course, sex-preponderance, clinical, genetic, and environmental covariates, could be observed. Method: Using data from the Avon Longitudinal Study of Parents and Children (female participants: 5,085; male participants: 5,028), we explored sex-stratified irritability latent profiles across 5 time points (∼ages 7-25 years) for irritability measured with the Development and Well-Being Assessment. We investigated associations with various clinical, genetic, and environmental covariates typifying behavioral, neurodevelopmental, and depressive conditions. Results: We identified 5 irritability profiles similar across sexes (low, child-limited, child/adolescent-limited moderate, child/adolescent-limited high, high-stable) and 2 sex-specific profiles: adolescent-onset (female participants) and fluctuating (male participants). Although most profiles were not distinguished by condition-specific covariates, 2 profiles showed some specificity with neurodevelopmental or depressive conditions: (1) the male high-stable profile was associated with attention-deficit/hyperactivity disorder diagnosis and genetic liability, and autism-like traits, and (2) the female adolescent-onset profile was associated with depression diagnosis and genetic liability, and adolescent/adult stressful life events. Conclusion: Irritability appears to be developmentally heterogeneous. Albeit often transdiagnostic, for some individuals irritability may align with neurodevelopmental or depressive conditions. This could have potential implications for classification and treatment. Study registration information: Exploring Possible Behavioural, Neurodevelopmental and Depressive Types of Irritability, Using a Developmental Approach; https://osf.io/av2s8/.