Affect dynamics in adolescent depression: Are all equilibria worth returning to?

Difficulties in emotion regulation during adolescence have been linked to depression. Early identification of deficits in emotion regulation may help prevent the onset of depression. This study investigated whether emotion regulation dynamics, particularly the strength of regulation to one's affective equilibrium (damping) inferred from the damped oscillator model, predicts future depressive symptoms in adolescents. We hypothesized that the relationship between damping and long-term outcomes would depend on the position of an individual's equilibrium. From July 2019 to May 2024, participants ( = 115) aged 12-15 completed smartphone-based ecological momentary assessment for 30 days, rating six emotions four times daily. The damped oscillator model was applied to each participant's time-series data, yielding person-specific frequency of oscillations (η) and damping (ζ) parameters. These parameters were then used to predict depressive symptoms at 6- and 12-month follow-ups controlling for baseline levels of depression. Results revealed that the interaction between the damping parameter and the equilibrium position significantly predicted depressive symptoms for sadness, but not for other emotions. For individuals with higher equilibrium levels of sadness, stronger damping predicted higher follow-up depressive symptoms. Additionally, higher frequency of oscillation around the equilibrium-representing greater elasticity and less rigidity-of two emotions (interest and happiness) predicted fewer depressive symptoms. These findings suggest that the adaptive value of rapid emotional recovery depends on one's baseline emotional state. Tracking emotion regulation dynamics of both positive and negative emotions may improve our ability to identify adolescents at risk for depression before symptoms emerge, thereby informing targeted intervention and prevention efforts. (PsycInfo Database Record (c) 2025 APA, all rights reserved).