Stressful life events and depression onset: A longitudinal investigation of depression course subtypes.

Most people who experience a first onset of major depression recover quickly and never have a recurrence, whereas a minority subsequently experience chronic or recurrent depression, thereby contributing disproportionately to depression's high public health burden. Distinguishing individuals at the time of first onset who are at greater risk for a severe course could provide important insights into the nature and treatment of depression. One key variable for consideration is stressful life events (SLEs). Substantial evidence documents that SLEs are more strongly associated with a first depressive episode and become progressively less associated with each successive recurrence. The explanation for this well-established research finding remains unclear, yet one explanation provided by the dual pathway model is that SLEs are more strongly associated with briefer, less frequent episodes, whereas stress plays a less significant role in more chronic and recurrent forms of depression. In this study, we compare the role of SLEs in time-limited depression (<12 months of lifetime depression) and chronic-intermittent depression (≥12 months of lifetime depression). In a 6-year prospective study of 135 adolescent females with a first-onset depressive disorder assessed using diagnostic and SLE interviews, we examined SLE count and eventual depression course subtype as predictors of first-onset depression. Increases in SLEs were generally associated with an increase in the hazard of first-onset depression for the time-limited depression youth, but not the chronic-intermittent depression youth. Findings suggest that major life stressors may have important theoretical and clinical implications for understanding the heterogeneity and course of depression. (PsycInfo Database Record (c) 2026 APA, all rights reserved).