A life course view on depression: Social determinants of depressive symptom trajectories over 25 Years of Americans' Changing Lives.

Objectives: This study investigates heterogeneity in trajectories of depressive symptomatology in a national sample of American adults followed over 25 years. Using an innovative combination of data and methods, we sought to illuminate how depressive symptoms change over adulthood in terms of their levels and severity across 25 years, and how the social determinants of health influence differences in those trajectory paths. Methods: Data come from the Americans' Changing Lives (ACL) study, a national sample of 3617 adults (age 25+) followed over 25 years (1986-2011). Depressive symptoms were assessed with an 11-item abbreviated version of the Center for Epidemiologic Studies-Depression scale (CESD). A second-order growth mixture model was used to assess measurement invariance (addressing questions of different or changing meaning of depression) and latent trajectories of change (addressing questions of changing severity levels with aging) in depressive symptomatology over adulthood. Results: Results indicate that the CESD was invariant across time, and depressive symptomatology followed a U-shaped form across the life course. Two latent trajectories of depressive symptoms were identified across the life course; one was a normative trajectory (60% of the sample) and the other (40% of the sample) had persistently high depressive symptoms over adulthood. Women, race/ethnic minorities, and those of lower socioeconomic position were more likely to be in the persistently depressed class. Discussion: Results are consistent with those of other studies demonstrating a U-shaped form of depressive symptoms across the life course. However, a substantial sub-population with persistent depressive symptomatology over adulthood was also identified, whose predictors suggest the need to take a social determinants of health approach to disparities related to serious and persistent mental illness.