Do Biomarkers of Stress Mediate the Relationship between Socioeconomic Status and Health?

Psychosocial stress is posited as one of the primary pathways linking socioeconomic status (SES) to health outcomes, via sustained activation of stress-related autonomic and neuroendocrine responses, especially elevated levels of cortisol. To date, little population-level work has tested the relationship between SES and biological markers of these stress responses. We analyzed data from a national survey of 972 middle-aged and elderly respondents in Taiwan including survey, clinical, and biological measures. We tested the relationships between SES, as measured by education and income, and 13 biomarkers representing functioning of the neuroendocrine system, immune/inflammatory systems, and the cardiovascular system. We also examined whether these biomarkers account for the observed relationship between SES and self-reported health and mobility difficulties in our sample. Lower SES men have greater odds of falling into the highest risk quartile for only 2 of 13 biomarkers, and show a lower risk for 3 of the 13 biomarkers, with no association between SES and cortisol. Lower SES women have a higher risk for many of the cardiovascular risk factors, but a lower risk for elevated readings of epinephrine, norepinephrine, and cortisol. Inclusion of all 13 biological markers does not explain the relationship between SES and health outcomes in our sample. These data do not support the hypothesis that stress, via sustained activation of the body?s stress response, is an important mediator in the relationship between socioeconomic status and health. Most notably, lower SES is not associated with higher levels of cortisol in either men or women.