Does Affect Explain Racial/Ethnic Differences in Diurnal Cortisol? A Daily Diary Study

• In Event: 2-181 - Understanding Cultural Differences and Similarities in Development: Evidence from Stress Neurobiology and Psychopathology

Integrative Statement

Racial/ethnic minorities are more vulnerable to mental and physical health problems, but little is known about the psychobiological underpinnings of these disparities. Theoretical accounts of these health disparities have argued they occur as a result of differential exposure to stressful life experiences, which in turn result in differences in the daily patterning of affective, cognitive, and biological processes that accumulate over time to foster psychopathology or physical illness (DeSantis et al., 2007; Levy, Heissel, Richeson, & Adam, 2016; Mays, Cochran, & Barnes, 2007; Susman, 2007). Surprisingly, however, little work has tested these assumptions by examining the links between daily psychological experiences and biological processes that may help explain long-term health disparities.
The current study sought to examine differences in cortisol diurnal patterns and positive and negative affect as an initial step towards elucidating long-term health disparities. A racially/ethnically diverse (60.54% racial/ethnic minority, 39.46% Non-Latino White; minority groups: n = 94 Asian American, n = 66 Latino, n = 40 African American, n = 24 Multiracial or Other race) sample of 370 adolescents (57.3% female) between the ages of 11.9 and 18 years (M = 14.65 years, SD = 1.39) participated in this study. These adolescents provided 16 cortisol samples (four samples per day across four days)—allowing the computation of diurnal cortisol slopes, the cortisol awakening response, and diurnal cortisol output (area under the curve)—as well as daily diary ratings of high-arousal and low-arousal positive and negative affect.
Consistent with prior research, we found that racial/ethnic minorities (particularly African American and Latino youth) exhibited flatter diurnal cortisol slopes compared to White youth. Additionally, there was a significant main effect of race for cortisol area under the curve (AUC) such that Latino youth exhibited lower AUC. Furthermore, African American and Asian American youth reported lower levels of positive affect (both high-arousal and low-arousal) compared to White youth. Intriguingly, racial/ethnic differences in affect did not explain differences in cortisol patterns. It is possible that early in development chronic stress associated with racial/ethnic minority status leads to increased daily cortisol output (Bush et al., 2011), but over time this results in downregulation of the HPA axis and lower AUC, CAR, and flatter slopes. Additionally, despite the fact that positive affect is associated with better health, lower morbidity, and greater longevity (Pressman & Cohen, 2005), the observed racial/ethnic differences in positive affect did not mediate the racial/ethnic differences in cortisol patterns.
We conclude by discussing potential reasons for these findings, including the need to refine models of relations between affect and HPA axis activity. Future research should take into account that racial/ethnic groups were heterogeneous and the differences between groups were small. Future studies should also help to elucidate the mechanisms behind the observed effects by attaining a deeper understanding of cultural development, which may help clarify these patterns and inform interventions aimed at mitigating health disparities.

Authors

• LillyBelle K. Deer, UC Davis
  Presenting Author

• Grant S Shields, University of California Davis
  Non-Presenting Author

• Susannah Ivory, Pennsylvania State University
  Non-Presenting Author

• Camelia E. Hostinar, University of California-Davis
  Non-Presenting Author

• Eva H. Telzer, University of North Carolina Chapel Hill
  Non-Presenting Author