Biological sex, socioeconomic position, and stress physiology among Native Americans: Findings from the Oklahoma Study of Native American Pain Risk III.

Native Americans (NAs) experience disproportionate exposure to chronic sociocultural stressors that may shape physiological stress systems and contribute to health disparities. Yet, little research has examined acute stress reactivity, stress recovery, and their predictors in NAs. The present study investigated the independent and joint effects of sex and socioeconomic position (SEP) on sympathetic-adrenomedullary (SAM), hypothalamic-pituitary-adrenal (HPA), and negative affective responses to the Trier Social Stress Test (TSST) in 120 healthy NA adults (74 women). SEP was assessed using objective (household income) and subjective (subjective social status) indicators. SAM (skin conductance level, heart rate, blood pressure), HPA (cortisol), and negative affect were measured during baseline, stress, and recovery. Men displayed robust stress responding across all measures, whereas women showed robust SAM and affective responses but blunted cortisol reactivity. Exploratory analyses suggested this difference was not likely explained by hormonal contraceptive use. Lower income was associated with heart rate blunting in both sexes and cortisol blunting among men. By contrast, cortisol blunting was consistent across the income gradient among women. Lower income was associated with poorer cortisol recovery in both sexes. Subjective social status was unrelated to stress outcomes. These findings suggest that sex and SEP jointly shape stress physiology among NAs and support an intersectionality-informed understanding of stress-system functioning. Future research is needed to further understand how sociocultural and structural stressors become biologically embedded in NA populations and contribute to stress-related health disparities, but to also identify sources of resilience.