Search

Psychosocial and socioeconomic adversity in early childhood (termed 'social adversity') can have lifelong detrimental effects on health and development. Physiological stress is one proposed mechanism by which social adversity 'gets under the skin'. There is substantial research interest in whether hair cortisol, a biomarker proposed to measure the cumulative physiological stress response over time, can illustrate this mechanism. As a result, a growing number of studies have tested for associations between indicators of social adversity and child hair cortisol. The aim of this paper is to conduct a comprehensive, systematic review of the evidence for associations between indicators of social adversity and hair cortisol, specifically in young children (birth to 8 years) published any time up to 31 December 2019. The literature search identified 44 published studies that met inclusion criteria. The studies examined associations between one or more indicators of social adversity and child hair cortisol across 35 independent cohorts comprising 8370 children. Indicators of adversity examined in the identified literature included socioeconomic factors (e.g. low parental education, low income and unemployment), psychosocial factors (e.g. parent stress, poor mental health and family violence), and children's direct exposure to maltreatment, abuse and stressful events. Across all indicators of adversity, a total of 142 associations with hair cortisol were examined. Evidence of associations was limited and inconsistent; 34/142 (24%) showed evidence of a positive association between adversity and higher hair cortisol, 8/142 (6%) showed a negative association, and more than two thirds (100/142, 70%) of all examined associations were null. The collective evidence appears insufficient to conclude that there is a relationship between social adversity and hair cortisol, as a measure of physiological stress response, in young children., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Physiological stress is thought to be one way that early adversity may impact children's health. How this occurs may be related to parental factors such as mothers' own stress and parenting behaviour. Hair cortisol offers a novel method for examining long-term physiological stress in mother-child dyads. The current study used hair cortisol to examine the role that maternal physiological stress and parenting behaviours play in explaining any effects of adversity on young children's physiological stress. This cross-sectional study comprised 603 mother-child dyads at child age 2 years, recruited during pregnancy for their experience of adversity through an Australian nurse home visiting trial. Hair cortisol data were available for 438 participating mothers (73%) and 319 (53%) children. Confirmatory factor analysis was used to define composite exposures of economic (e.g. unemployment, financial hardship) and psychosocial (e.g. poor mental health, family violence) adversity, and positive maternal parenting behaviour (e.g. warm, responsive). Structural equation modelling examined maternal mediating pathways through which adversity was associated with children's physiological stress. Results of the structural model showed that higher maternal and child physiological stress (hair cortisol) were positively associated with one another. Parenting behaviour was not associated with children's physiological stress. There was no evidence of any mediating pathways by which economic or psychosocial adversity were associated with children's physiological stress. The independent association identified between maternal and child hair cortisol suggests that young children's physiological stress may not be determined by exogenous environmental exposures; endogenous genetic factors may play a greater role.

Objective: Children exposed to early adversity (eg, financial hardship, family violence, parent mental health difficulties) are at greater risk of poor health outcomes. Physiological stress is one mechanism thought to explain this pathway. We investigated associations between adversity and young children's health and whether child stress (measured using hair cortisol) mediated these associations., Methods: This was a cross-sectional study of 3-year-old children whose mothers were recruited during pregnancy, through the right@home trial, for their experience of adversity. Using total counts of 9 sociodemographic and 9 psychosocial indicators of adversity, regression models examined relationships among adversity risk counts, child hair cortisol (potential mediator), and 5 health outcomes: externalizing and internalizing problems, physical and socioemotional wellbeing, and overweight/obesity., Results: Hair cortisol data were available for 297 out of 500 (59%) participating children. When examined separately, sociodemographic adversity risk was associated with higher externalizing problems, and psychosocial adversity risk was associated with higher externalizing problems and poorer physical/socioemotional wellbeing. When examined together in a single model, psychosocial (but not sociodemographic) adversity was associated with higher externalizing problems (unstandardized mean difference [β], 0.53; P = .002) and poorer physical wellbeing (β, 1.19; P = .009); higher hair cortisol was associated with higher externalizing problems (β, 0.76; P = .02). There was no evidence that stress (hair cortisol) mediated associations between adversity and health., Conclusions: In 3-year-old children, we found no evidence that physiological stress (hair cortisol) mediated associations between adversity risk and children's health. Hair cortisol may be limited as a single measure of stress, or physiological stress may not be a mechanism for explaining the effects of adversity on these young children's health., (Copyright © 2019 Academic Pediatric Association. Published by Elsevier Inc. All rights reserved.)

Hair cortisol has the potential to provide insight into young children's long-term stress response to social adversity. This study investigated associations between children's exposure to adversity from pregnancy to 2 years of age and their hair cortisol at 2 years, using a longitudinal cohort of children enriched for adversity risk, whose mothers were recruited during pregnancy through the "right@home" trial. Exposures were 18 maternal socioeconomic and psychosocial indicators of adversity, examined as concurrent, cumulative, and longitudinal exposure from pregnancy to 2 years. Hair samples were analyzed from 319/603 (53%) children participating at 2 years. Multivariable regression analyses for concurrent exposure showed three indicators of adversity were associated with higher hair cortisol (housing tenure of public rental, paying board or living rent free; not living in a safe place; higher maternal stress symptoms), one with lower hair cortisol (housing problems), and 14 indicators with no evidence of association. There was no evidence of association for the cumulative adversity count. Longitudinal exposure showed "intermittent" and "persistent" high maternal stress symptoms were associated with higher hair cortisol. The small number of associations identified suggests that hair cortisol is limited as a measure of stress response to social adversity in children at 2 years., (© 2019 Wiley Periodicals, Inc.)