Differences in associations between coping styles and depressive symptoms across pandemic-related periods among university students with subthreshold depressive symptoms: a serial cross-sectional study

The coronavirus disease 2019 (COVID-19) pandemic has significantly affected the mental health of university students. However, differences in mental health and coping styles across pandemic-related periods remain insufficiently understood. Although coping styles have been associated with depressive symptoms, it remains unclear whether these associations differ across pandemic-related periods among students with subthreshold depressive symptoms, a high-risk group for clinical depression. This study examined differences in depressive symptoms, disordered eating behaviors, and coping styles across pandemic-related periods, with a particular focus on the association between coping styles and depressive symptoms among students with subthreshold depressive symptoms. This serial cross-sectional study included 24,438 Japanese university students who were assessed during the pandemic (2021–2022), transition (2023), and post-pandemic (2024–2025) periods. Depressive symptoms, disordered eating behaviors, and coping styles were assessed using the Beck Depression Inventory-II (BDI-II), Eating Attitudes Test-26 (EAT-26), Bulimic Inventory Test, Edinburgh (BITE), and Coping Inventory for Stressful Situations (CISS). Associations between coping styles and depressive symptoms among students with subthreshold depressive symptoms were examined using partial correlation and multiple regression analyses. The BDI-II and BITE scores were lower during the transition and post-pandemic periods than during the pandemic period. The EAT-26 scores showed a significant interaction between period and sex. The CISS-T scores were lower during the pandemic than during the transition and post-pandemic periods, whereas the CISS-A scores were higher in the post-pandemic period. Among students with subthreshold depressive symptoms, CISS-E scores were positively correlated with depressive symptoms across all periods, whereas the associations involving CISS-T scores differed across periods. Depressive symptoms and coping styles among university students differed across the pandemic-related periods. Among students with subthreshold depressive symptoms, emotion-oriented coping showed a consistent association with depressive symptoms, whereas associations involving task-oriented coping differed across periods. These findings suggest that the association between coping styles and depressive symptoms may differ according to environmental conditions. Considering the environmental context may be important when developing preventive and supportive interventions for students’ mental health.