Caregiver depression is associated with hair cortisol in a low-income sample of preschool-aged children.

BACKGROUND: Caregiver depression and child temperamental characteristics such as effortful control have been associated with child dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis. Hair cortisol concentrations (HCC) has been increasingly adopted as an integrated marker of HPA axis activity. This study examined the associations between caregiver depressive symptoms, caregiver social support, child effortful control, and child HCC in a sample of a high-risk, low-income preschool-aged children. METHODS: 154 caregivers comprised mostly of mothers and their children (2-to-5 years) who were enrolled in a birth cohort study conducted in poor urban neighborhoods of São Paulo, Brazil. Through personal interviews at their homes, caregivers provided ratings of their psychosocial experiences and of their child's behavior. Hair was sampled from children with at least a 3-cm hair length. RESULTS: In a multivariable regression analysis, an unadjusted model showed child age to be negatively associated with HCC (ß = -0.32, p < .001). The adjusted model, which accounted for child age and sex, showed a positive relationship between caregiver depressive symptoms and HCC (ß = 0.22, p < .01). Caregiver social support and child effortful control were not associated with HCC. CONCLUSIONS: The elevated HCC among children with caregivers reporting greater depression risk is consistent with prior findings showing elevated HCC among children exposed to persistent stress. Stabilization of child HCC may be occurring within preschool children given the negative association between HCC and age. Greater research is needed to determine whether the effects of caregiver social support and effortful control can be captured through HCC.

An assessment of hair cortisol among postpartum Brazilian mothers and infants from a high-risk community in São Paulo: Intra-individual stability and association in mother-infant dyads.

This study examined maternal-infant synchrony of hair cortisol at 12 months after birth and the intra-individual stability of maternal hair cortisol in the postpartum period. Participants were selected from an ongoing São Paulo birth cohort project, where families are considered to be "high-risk" due to their chronic stress experiences, with the majority living in slums (favelas). Cortisol was collected through 3-cm segments of hair samples, with values representing approximate levels of cortisol from 9 to 12 months for mothers and children and 6 to 12 months for mothers. Maternal and infant cortisol values reflecting chronic stress 9-12 months after birth were highly correlated (r = .61, p < .001); earlier maternal cortisol levels (6-9 months) and child cortisol levels at 9-12 months (r = .51, p < .001) were also correlated. Maternal cortisol values showed stability over time (r = .79, p < .001). These maternal-infant correlations are high compared to the existing literature on hair cortisol in other mother-child dyads, suggesting stronger synchrony under high-risk contexts where families are faced with challenging circumstances.