Links Between Socioeconomic Status, Daily Depressive Affect, Diurnal Cortisol Patterns, and All-Cause Mortality

Socioeconomic status (SES) remains a robust risk factor for mortality. Various theoretical models postulate that lower SES is associated with higher negative affect, which then initiates a cascade of physiological disturbances that contribute to illness and early mortality. However, few studies have explicitly investigated the interplay between psychological and biological factors in determining SES disparities in mortality. This study examined the role of daily negative affect and cortisol secretion in explaining the SES-mortality link in a large sample of US adults.

Using data from the Midlife in the United States study (n = 1735, mean [standard deviation] age = 56.40 [12.10] years, 56.4% female), we tested longitudinal associations between SES, daily negative affect, daily cortisol levels, and all-cause mortality 13 years later. Daily negative affect was classified into three clusters reflecting depressive affect, anxiety, and anger.

Higher SES was linked to a lower risk of all-cause mortality (hazard ratio = 0.94, 95% confidence interval = 0.90 to 0.97). Furthermore, there was a sequential link between higher SES and lower mortality through lower daily depressive affect and a steeper ("healthier") diurnal cortisol slope (indirect effect = -0.0007, 95% confidence interval = -0.0014 to -0.0002). Daily anxiety and anger were not associated with cortisol levels or mortality (p values > .05).

These findings suggest that daily negative emotional experiences and the hypothalamic-pituitary-adrenal axis functioning may constitute important psychological and physiological pathways underlying the link between SES and all-cause mortality.