Socioeconomic Status, Psychosocial Stress, and Mortality in the United States

Abstract

Background: Socioeconomic status has a well-documented inverse association with morbidity and mortality. Psychosocial stress is one of the most frequently cited pathways hypothesized to drive social inequalities in health. Yet, considerable debate and conflicting evidence persists regarding the associations between psychosocial stress and physical health outcomes, it’s precise mechanisms of action, and its role in perpetuating social inequalities in health. Therefore, this dissertation explores the association between stress and all-cause mortality, the relative contributions of hypothesized mechanisms of the stress-mortality relationship, and the extent to which stress explains socioeconomic inequality in all-cause mortality. Methods: All analyses performed in this dissertation were conducted on longitudinal data from the survey of Midlife Development in the United States (MIDUS). In Chapter 1, I conducted a survival analysis to determine whether various stress measures were associated with all-cause mortality over the follow-up period from 1995 to 2015 after adjustment for sociodemographic factors and baseline health. In Chapter 2, I utilized multiple mediator mediation analysis to determine the relative contributions of behavioral, biological, and psychological pathways to the stress-mortality relationship. Finally, in Chapter 3, I performed a causal mediation analysis to determine the extent to which measures of psychosocial stress explained socioeconomic inequality in mortality. Chapters 1 and 3 also investigated whether findings varied by gender. Results: Psychosocial stress was associated with all-cause mortality, even after adjustment for confounding by sociodemographic factors and pre-existing health conditions. This association was largely explained by health behaviors and to lesser extent biological risk factors. Stress explained a moderate portion of the socioeconomic inequality in mortality. Conclusions: Psychosocial stress is an important determinant of mortality and social inequalities in mortality, largely due to its effect on health behaviors and biological risk factors. These associations may vary by type of stress as well as gender, which may explain some of the inconsistencies observed in the literature. Programs and policies aimed at improving public health and reducing inequalities in health should consider including stress reduction as part of a broader strategy addressing the material and behavioral determinants of health.