Allostasis model facilitates understanding race differences in the diurnal cortisol rhythm

Area of Science:

• Psychoneuroendocrinology
• Stress Physiology
• Social Determinants of Health

Background:

• Allostasis theory posits cumulative stress impacts physiology.
• Hypothalamic-pituitary-adrenal (HPA) axis dysregulation is linked to age-related pathology.
• Early life stressor exposure may create race-based differences in HPA regulation.

Purpose of the Study:

• To investigate race differences in HPA axis regulation among young adults.
• To examine the role of stressor exposure, including racism, in race-based HPA differences.
• To assess the association between HPA functioning and mental health outcomes.

Main Methods:

• Salivary cortisol was measured in 275 young adults (Black and White) over 3 days.
• Four daily cortisol samples were collected to assess waking and diurnal rhythm.
• Hierarchical linear models analyzed race, stressor exposure, and HPA functioning.

Main Results:

• Black young adults exhibited flatter cortisol slopes (lower waking, higher bedtime cortisol) than Whites.
• Stressor exposure had more robust associations with HPA functioning in Whites.
• Flatter HPA slopes correlated with poorer mental health outcomes across both races.

Conclusions:

• Social contextual factors, including racism, influence HPA axis regulation and cortisol rhythms early in life.
• Differential stressor exposure contributes to race-based physiological differences.
• HPA axis dysregulation is linked to adverse mental health outcomes in young adulthood.