Concurrent and prospective associations between family socioeconomic status, social support and salivary diurnal and hair cortisol in adolescence

Background Exposure to socioeconomic adversity is hypothesized to impact hypothalamic–pituitary–adrenal (HPA) axis activity and cortisol secretion, but existing evidence is inconsistent. Yet, few studies have investigated this association using a developmental approach that considers potential protective contextual factors. This study examined the role of stability and changes in family socioeconomic status (SES) in the prediction of multiple cortisol indicators and tested whether social support moderated these associations. Methods Participants were part of a population‐based sample of twin pairs recruited at birth. Family SES was assessed in early childhood (ages 0–5) and mid‐adolescence (age 14). Social support was assessed at ages 14 and 19. Diurnal cortisol ( n = 569) was measured at age 14 at awakening, 30 min later, in the afternoon and evening over four non‐consecutive days. Hair cortisol concentration (HCC, n = 704) was measured at age 19. All data were collected before the pandemic and multilevel regression models were conducted to account for the nested data structure. Results Youth exposed to lower family SES levels in childhood and mid‐adolescence had a flatter diurnal slope and higher HCC compared with those who experienced upward socioeconomic mobility in mid‐adolescence. Contrastingly, mid‐adolescence SES showed no association with the diurnal slope or HCC for youth from higher‐SES households in early childhood. Moreover, youth raised in higher‐SES families in early childhood had a higher CAR in mid‐adolescence if they reported greater social support in mid‐adolescence. Social support also moderated the SES‐cortisol association in mid‐adolescence, with higher‐SES youth showing higher awakening cortisol secretion when reporting more social support. Conclusions Our findings support the hypothesis that early socioeconomic adversity sensitizes HPA axis activity to later socioeconomic disadvantage, which may bear consequences for socioemotional and behavioral functioning.