Discrimination and Cortisol Dynamics among Older African Americans Adults

Abstract

Discrimination has been found to predict self-report measures of general health as well as surrogate and clinical endpoints of various diseases. As the connection between discrimination and disease and pre-disease states became evident, research efforts started to include more investigations of the purported biological mediators. Dysregulation in the daily activity of the Hypothalamic-Pituitary-Adrenal (HPA) axis has been proposed as one of these mechanisms. The current study leverages data collected in the Health among Older Adults Living in Detroit project to investigate the relationship between three measures of discrimination (lifetime discrimination, habitual everyday discrimination, and daily everyday discrimination) and diurnal cortisol secretion in a sample of 203 older African Americans. Study results indicated that individuals reporting higher levels of lifetime discrimination experienced morning hypocortisolism and flatter diurnal cortisol slopes. Neither habitual (the estimated routine frequency of day-to-day experiences of unfair treatment) nor daily (the occurrence of discrimination experiences in a short and defined period – five days in our study) everyday discrimination were associated with cortisol secretion. However, exploratory analyses also showed that prior daily everyday discrimination was significantly associated with blunted cortisol awakening response (CAR) the next day. The link between lifetime discrimination and daily cortisol found in our study seems to support the stress accumulation model (stressors accumulate over time and have an additive effect on health processes and outcomes). Overall, our findings underline the role played by discrimination in modulating the activity of the HPA axis, whose regulation has critical implications for healthy aging.