Irritability: associations with real-time affect dynamics, social interactions, and daily substance use in older adolescents.

Irritability is a common and clinically significant symptom associated with a wide range of negative outcomes. Ecological Momentary Assessment (EMA) is a valuable tool for capturing experiences, such as emotions, social interactions, and substance use in real-time, and may be useful in understanding how irritability is related to everyday functioning. We investigated cross-sectional associations between a widely used self-report irritability rating scale and affect dynamics, social interactions, and substance use captured with EMA (5 surveys daily for 14 days) in 349 18-year-olds. We also examined the associations of self- and parent-reported irritability at ages 12 and 15 with the age 18 EMA variables to explore whether these relationships persist over time. Youth-reported irritability at age 18 was linked to greater intensity, variability, and inertia of irritability, sadness, and anxiety, less positive and more negative interpersonal experiences, and greater cigarette and drug use. Most effect sizes were in the medium-small range. Associations of youth- and parent-reported irritability at ages 12 and 15 with the age 18 EMA measures were generally similar, although smaller in magnitude. Findings contribute to understanding how irritability is manifested in real-time affect dynamics and interpersonal functioning, as well as daily substance use. Most effects were evident over the course of up to 6 years - that is, early adolescent irritability, reported by both youth and their parents, was associated with similar real-time affect dynamics and interpersonal experiences at age 18. This study contributes to the literature on the developmental psychopathology of irritability by extending findings to everyday functioning.