Abstract
BACKGROUND: The incidence of depression among adolescents has risen significantly over the past decade. Emotional dynamics, including variability, instability, and inertia of positive affect (PA) and negative affect (NA), are potential risk factors for depressive psychopathology. However, limited longitudinal evidence exists on how these emotion dynamics relate to depression, particularly in collectivistic cultural contexts, where emotional expression and regulation are shaped by social and familial expectations. This study aimed to investigate the longitudinal associations between emotion dynamics-variability, instability, and inertia of PA and NA-and subsequent depressive symptoms among Chinese adolescents. METHODS: Data were collected from middle school students in Taizhou, China, between November 2021 and April 2022. Participants completed baseline surveys and experience sampling assessments, reporting their emotional states ten times daily over five consecutive weekdays. Depressive symptoms were assessed using the Children's Depression Inventory (CDI), while emotional dynamics (variability, instability, and inertia) were derived from the experience sampling data. Logistic regression models were employed to examine whether emotion dynamics predicted depressive symptoms at 1-month and 3-month follow-ups. RESULTS: A total of 448 participants completed all study procedures and were included in the analysis. Emotional variability and instability in PA and NA were longitudinally associated with depressive symptoms at both 1-month and 3-month follow-ups. After controlling for mean affect levels, PA variability and instability, but not NA, were uniquely linked to depressive symptoms. Emotional inertia showed no significant association with subsequent depressive symptoms. Emotional variability and instability in PA and NA also predicted the development of new symptoms in adolescents without baseline depression (n = 372). CONCLUSIONS: Emotional variability and instability of PA and NA were longitudinally associated with changes in depressive symptoms and the development of new symptoms among adolescents. These emotion dynamics provide insights into real-world emotional processing and offer important targets for adolescent depression interventions.