The longitudinal and bidirectional association between irritability and depressive symptoms in Icelandic adolescents

Abstract

Depressive symptoms and irritability in adolescence are common referrals for mental health services and major health problems. These psychiatric traits commonly co-occur; however, the nature of their relationship is poorly understood. This study aimed to examine the bidirectional and longitudinal association between irritability and depressive symptoms and gender differences in these associations. Participants comprised 2,271 adolescents (51.30% girls) born in 2004 from the LIFECOURSE study who completed self-report measures on depressive symptoms and irritability in 2017, 2018, and 2019. Using random intercept cross-lagged panel models (RI-CPLMs), the association between irritability and symptoms of depression were investigated at the within-person level, for the whole sample and for girls and boys, respectively. The results for the whole sample demonstrated that irritability negatively contributed to later depressive symptoms and vice versa. When stratified by gender, support for only the latter association was found for both adolescent girls and boys. Expanding on previous knowledge, these findings suggest that depressive symptoms are an important predictor of irritability and highlight that irritability is part of the manifestation of depression in adolescents.