Developmental origins of flatter cortisol rhythms: Socioeconomic status and adult cortisol activity

Objective: Low socioeconomic status (SES) is associated with increased psychosocial stress among low-income persons, which could contribute to differences in activity of the HPA axis (assessed by diurnal cortisol profiles). The current article investigates associations of SES from different developmental stages with cortisol profiles. Methods: Using data from a large, socioeconomically diverse birth cohort (N=1,490) in Cebu, Philippines, the current study compares the relative and joint contributions of SES from five developmental periods, between the prenatal/birth period and early adulthood, to adult cortisol, and examines the effects of chronic exposure to low SES. Results: Chronically low SES from infancy through early adulthood predicts the highest bedtime cortisol levels, lowest cortisol awakening responses (CARs), lowest total cortisol levels across the day (area under curve or AUC), and the flattest cortisol rhythms between wake up and bedtime, a profile associated with poorer health. Results indicate that cumulative economic strain (between the prenatal period and early adulthood) predicts flatter cortisol rhythms more consistently than SES from any particular period. Conclusion: Interventions focusing on the psychosocial stressors associated with economic deprivation during any period from infancy to adulthood may be helpful, but targeting interventions across multiple periods may have the greatest impact. Interventions aimed at improving economic conditions between infancy and early adulthood may have implications for long-term changes in HPA axis functioning.