Differential sensitization of parenting on early adolescent cortisol: Moderation by profiles of maternal stress
Introduction
The hypothalamic–pituitary–adrenal (HPA) axis is a critical component of the stress-response neurobiological system that responds to physical and psychological stressors via a cascade of neuroendocrine hormones, ending with cortisol. Although genetic and prenatal programing effects are linked to neurobiological development and functioning (Bartels et al., 2003, Belsky and Pluess, 2009), the development of the HPA axis is also shaped by environmental experiences (Del Giudice et al., 2011); this is especially true of early caregiving experiences, as evidenced in both nonhuman primates (Sánchez, 2006) and children (Hostinar et al., 2014, McEwen, 2012). Considerable work in this area has centered around infants and young children, thus, much of our understanding of how parenting practices influence the developing HPA axis is based on sensitive, responsive, and consistent parenting (Hostinar et al., 2014), the fundamental caregiving behaviors for infants and young children (Ainsworth et al., 1974). However, little is known about the effects of parenting practices on the HPA axis in early adolescence, a developmental period associated with heightened stress and emotional responsiveness to the social environment (Steinberg and Morris, 2001), as well as increased conflict with parents (Marceau et al., 2015). Accumulating evidence suggests that the HPA axis becomes more reactive to stress during adolescence (Gunnar et al., 2009, Klein and Romeo, 2013, Lupien et al., 2009). Thus, a better understanding of how key parenting behaviors are related to HPA functioning in early adolescence is needed and may have important clinical implications for designing effective parenting interventions aimed at improving stress reactivity and regulation.
Extensive research has identified inconsistent discipline, poor parental supervision, and harsh parenting as salient parenting behaviors linked to adolescents’ poor emotion regulation, externalizing behavior problems, and substance use (Duncombe et al., 2012, Luyckx et al., 2011, MacKenzie et al., 2013). Albeit limited, evidence suggests that as with neglectful early care (Bruce et al., 2009, Johnson et al., 2011), poor parental supervision (Martin et al., 2014) has been linked to flatter slope in morning-to-evening cortisol in older children. In contrast, inconsistent discipline and harsh parenting have not been found to affect diurnal cortisol rhythms in early adolescence (Martin et al., 2012, Martin et al., 2014). It may be that in comparison to inconsistent discipline and harsh parenting, parental supervision is a better predictor of cortisol regulation in older children. Alternatively, because parenting does not occur in isolation, parents’ experiences of stress may differentially affect the influence of parenting behaviors on HPA axis functioning.
Numerous studies have linked environmental stressors, particularly in mothers, to their children’s dysregulated HPA functioning. Parental stress (Fisher and Stoolmiller, 2008, Koch et al., 2010), interparental aggression (Sturge-Apple et al., 2012), parental substance use while controlling for the number of adverse life events experienced by their children (Evans et al., 2013), maternal depression (Lupien et al., 2000), and socioeconomic disadvantage (Lupien et al., 2000, Zalewski et al., 2012) have all been associated with dysregulated child cortisol. Experiences of childhood abuse have likewise been associated with dampened cortisol reactivity in adulthood (Carpenter et al., 2007). In contract, less is known about how maternal childhood abuse impacts her child’s cortisol regulation. This body of research highlights the link between maternal stress and youths’ cortisol reactivity and regulation, yet the manner in which such stressors influence the relationship between parenting behaviors and child cortisol is not well understood. Moreover, a limitation of the aforementioned research is that most studies examined individual stressors in isolation (Sturge-Apple et al., 2012) or combined the stressors into a composite (Martin et al., 2012) or cumulative risk index (Zalewski et al., 2012). These methods lack specificity, as such stressors often co-occur in meaningful ways. A more ecologically valid way to examine the effects of maternal stress involves assessing multiple indicators of stress to determine distinct patterns of co-occurrence, in tandem with examining the more proximal role of parenting behaviors.
Our study used a latent profile analytic approach to investigate how phenotypes of maternal stress moderate the relationship between inconsistent discipline, poor parental supervision, and harsh parenting behaviors and early adolescent diurnal cortisol rhythms in 9–12-year-olds (Fig. 1). We examined multiple indicators of mothers’ current as well as childhood stress due to exposure to child abuse. Based on findings that childhood abuse history alone may be insufficient but when combined with ongoing stress in the form of depression or other psychological stressors, is related to neurobiological dysregulation (Heim et al., 2004, Kaufman et al., 1997, Rinne et al., 2002), we expected at least 4 groups with distinctive stress profiles: a low stress group, a group with current high levels of stress, a group with high levels of childhood but not current stress, and a group with high levels of current and childhood stress. Further, based on prior findings on the association between parenting behaviors and diurnal cortisol rhythms in early adolescence (e.g., Martin et al., 2014) we hypothesized that there would be a direct link between parenting behaviors and diurnal cortisol rhythms in early adolescence. We further hypothesized that the associations between parenting behaviors and youths’ diurnal cortisol rhythms would be stronger in the presence of maternal stress, particularly for combined childhood and current stress (e.g., Heim et al., 2004).
Section snippets
Participants
The present data were collected as part of a follow-up assessment from youths and families who had participated in the Healthy Families America (HFA) San Diego clinical trial from child birth to age 3 (Landsverk et al., 2002). For detailed information about the original study and sample see Martin et al. (2014). For our study, a total of 239 families, of the original 488, were recruited. Families were excluded if the participating caregiver was not the youth’s biological mother (n = 33), if the
Latent profile analysis of maternal stress
Table 2 shows the model fit statistics from step 1 of the 3-step LPA from models with 2–5 profiles. Although the BLRT indicated that each model had a significantly better fit than did the prior model, the information criteria indicators, in general, indicated that the 4-profile model had the best fit. Additionally, the fit indices of the 5-profile model increased from those of the 4-profile model, which had the lowest values. Entropy was also the highest for the 4-profile model and in the
Discussion
The purpose of the present study was to examine whether the association between parenting behaviors and youth’s HPA axis functioning would vary depending on parental stress in early adolescence. The findings indicated that when multiple potential stressors are considered, the mothers in this study experienced distinctive patterns of stress, with three stress profiles – current parenting stress, concurrent parenting and childhood stress, and childhood stress – and one low stress profile.
Conclusions
Despite its limitations, our study contributes to the literature in numerous ways. Our study supports a model of differential sensitization of the HPA axis based upon maternal parenting practices. The relationship of the specific parenting behaviors examined – inconsistent discipline, parental supervision, and harsh parenting – with adolescent diurnal cortisol profiles depended on mothers’ experience of current and ongoing stress. This finding suggests that the widely accepted one-size-fits-all
Conflict of interest
The authors have no conflicts of interest to disclose.
Role of funding source
Funding for this study was provided by the following grants: HD045894, NICHD, U.S. PHS; MH059780 and MH078105, NIMH, U.S. PHS; and DA023920, NIDA, U.S. PHS. The funding organizations had no further role in the study design; in the collection, analysis, and interpretation of the data; in the writing of this paper; or in the decision to submit the paper for publication.
Contributors
Phil Fisher designed the original study and wrote the protocol. All of the authors made contributions to the conceptualization of the study. Christina Gamache Martin conducted the literature review and statistical analyses. Hyoun Kim assisted in and reviewed the analyses. Christina Gamache Martin wrote the first draft of the manuscript. All authors contributed to and approved of the final manuscript.
Acknowledgements
Funding for this research was provided by the following grants: HD045894, NICHD, NIH, U.S. PHS; MH059780, and MH078105, NIMH, NIH, U.S. PHS; and DA023920, NIDA, NIH, U.S. PHS. The authors thank the families who participated in the study; John Landsverk, Cynthia Connelly, and their colleagues at the Child and Adolescent Services Research Center in San Diego, and Cheryl Mikkola for editorial assistance.
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