The Mediating Role of Intolerance of Uncertainty in the Relationship Between Coping Styles and Perfectionism Among Individuals With Depression

Abstract Background: Perfectionism and intolerance of uncertainty (IU) are increasingly recognized as transdiagnostic risk factors for depression. Coping styles may determine how these vulnerabilities contribute to psychopathology, yet the mechanisms remain insufficiently clarified. Objective: This study investigated the mediating role of IU in the relationship between coping styles and perfectionism, and its subsequent impact on depressive severity. Methods: A cross-sectional design was conducted with 320 individuals clinically diagnosed with major depressive disorder recruited from psychological centers in Sabzevar, Iran. Participants completed validated measures of coping styles (CISS), perfectionism (FMPS; MPS), IU (IUS-12), and depression severity (BDI-II). Structural equation modeling (SEM) with robust maximum likelihood estimation and bootstrapped confidence intervals (5,000 resamples) was applied to test the hypothesized mediation model. Results: The measurement model demonstrated strong reliability and validity. The structural model showed excellent fit (χ²/df = 1.90; RMSEA = .058; CFI = .951; TLI = .944). Problem-focused coping negatively predicted IU, whereas emotion-focused coping positively predicted IU. IU strongly predicted perfectionism, which in turn predicted depression severity. Bootstrapped indirect effects confirmed that IU mediated both adaptive and maladaptive coping pathways. The model explained 63% of the variance in perfectionism and 41% in depression severity. Conclusion: Findings highlight IU as a robust mediator linking coping styles to perfectionism and depression. Emotion-focused coping exacerbates vulnerability through IU, while problem-focused coping exerts protective effects. Interventions enhancing tolerance of uncertainty and adaptive coping may reduce perfectionism and depressive symptoms. Keywords: Perfectionism, Intolerance of Uncertainty, Coping Styles, Depression