Abstract

Background To assess whether linear effects or threshold effects best describe the association between early adverse stress (EAS) and complex and severe depression (i.e., depression with treatment resistance, psychotic symptoms, and/or suicidal ideation), and to examine the attributable risk of complex and severe depression associated with EAS. Methods A cross-sectional study was conducted using deidentified clinical data (on demographics, presence of complex and severe depression, and exposure to seven types of EAS) from 1,013 adults who were seen in an outpatient mental health clinic in Santiago, Chile, for a major depressive episode. Multivariate logistic regressions were fitted to estimate odds ratios (ORs), using a bootstrap approach to compute 95% bias-corrected confidence intervals (95% BC CIs). A detailed examination of the cumulative risk score and calculations of the attributable risk was conducted. Results Exposure to at least five EASs was reported by 3.6% of the sample. In the multivariate logistic regression models, there was a marked increase in the odds of having complex and severe depression associated with exposure to at least five EASs (OR = 4.24; 95% BC CI: 1.25 to 9.09), according to a threshold effect. The attributable risk of complex and severe depression associated with exposure to at least one EAS was 36.8% (95% BC CI: 17.7 to 55.9). Conclusions High levels of EAS distinctively contribute to complex clinical presentations of depression in adulthood. Patients with complex clinical presentations of depression and history of EAS should need a differentiated treatment approach, particularly those having high levels of EAS.