Lifetime Stressor Severity and Diurnal Cortisol in Older African American Adults: A Comparison of Three Theoretical Models

Multiple theoretical models have been proposed to explain how stressor exposure across the life course relates to the functioning of the hypothalamic-pituitary-adrenal (HPA) axis, as indexed by daily cortisol secretion. However, this association remains understudied in African Americans. The present study tested three competing models of stressor severity across the lifespan and diurnal cortisol secretion in a sample of 203 older African American adults. The cumulative model emphasizes total stressor severity across the lifespan, the biological embedding model emphasizes early-life stressor severity, and the sensitization model instead emphasizes the interaction between early-life and recent stressor severity. Lifetime stressor severity was assessed using the Stress and Adversity Inventory for Adults (Adult STRAIN). Analyses did not support any of the three models tested but, rather, a stressor characteristics perspective, wherein the severity of exposure to specific stressor characteristics was associated with blunted diurnal cortisol slopes. Sensitivity analyses revealed that early life stressor count, rather than severity, was associated with blunted diurnal cortisol slopes. Rather than supporting one of the three competing models of stressor severity, our findings provide preliminary evidence for a stressor characteristics approach and the biological embedding model when examining how lifetime stressor exposure affects HPA-axis activity.