Harsh parenting, physical health, and the protective role of positive parent-adolescent relationships
Introduction
Harsh parenting is associated with poorer child physical health (Brody et al., 2013, Miller et al., 2011, Repetti et al., 2002) including long-term effects on health outcomes (Dube et al., 2009, Wegman and Steltler, 2009). This association is often attributed to a causal effect of harsh parenting on the adolescent's biological functioning (Miller et al., 2011, Shonkoff et al., 2009) and health-related behaviors (Anda et al., 1999, Hillis et al., 2001). In other words, harsh parenting is thought to have a negative influence over time on physical health. However, this literature is based principally on cross-sectional retrospective reports, which provide limited evidence for causal claims due to their significant limitations (Hardt and Rutter, 2004). In the present study, we examined the association between parental harshness and changes in adolescent physical health over time using prospective longitudinal data.
As evidenced by the modest effect sizes from prior studies (e.g., Brody et al., 2013), some children and adolescents may be less subject to the hypothesized health risks of harsh parenting than others. Theoretical work suggests that positivity in the context of close relationships (Pietromonaco et al., 2013) is health protective, and this idea is supported by cross-sectional data from both human populations (Schafer et al., 2014) and nonhuman populations (Francis and Meaney, 1999, Meaney and Szyf, 2005). In the current study we assess the degree to which warmth from one parent buffers the hypothesized health risk of harshness from the other parent during adolescence.
Harsh parenting includes negative affect, potentially physical aggression, and is driven more by the parent's emotional reactions than the best interests of the child (Rueger et al., 2011). Our hypothesis of harsh parenting predicting changes in physical health draws heavily from the theoretical framework of Biological Embedding (Bush and Boyce, 2014, Hertzman, 2012, Miller et al., 2011). According to this framework, early stress that is chronic and severe potentiates the expression of physiological responses that anticipate continuity in those environmental characteristics. That is, from white blood cell activity, to hormone release, to potentiation of neurotransmitter receptor sites, the body shifts to a high-vigilance state that leads to a “weathering” effect on health including premature aging, and early onset of chronic disease.
In a recent review, Miller et al. (2011) report that child health is affected by stress that is severe, and chronic. They define severe stress as “difficulties that fall outside the normal range of what children normatively experience in developed countries” (p. 960) and chronic stress as “an experience where the stimulus [or threat posed by a stimulus] remains present in the child's life over a lengthy period of time” (p. 960).” In the current study, we propose that parents who reject, coerce, hit, and are self-centered during a video recorded interaction with their child fall outside the normal range of expected child experience in developed countries. Parenting behavior is stable over time (Schofield and Weaver, 2015), and most children are exposed to their parents' behavior for almost two decades. This supports classifying harsh parenting as a chronic stressful environment (Brody et al., 2013, Repetti et al., 2002, Shonkoff et al., 2009). Acknowledgement of the potential role of harsh parenting on physical health is particularly important because of the exposure period. The developing brain is relatively more receptive to environmental signals during childhood and adolescence (Barker et al., 2005, Johnson, 2005), and the resulting effects can last throughout the lifespan (McGowan et al., 2009, Wegman and Steltler, 2009).
There are several reasons to expect that harsh parenting could affect adolescent's metabolism and physical health. Central to the biological embedding framework is biological mediation. For example, when parents are harsh, the adolescent's emotional needs are unlikely to be met (Cicchetti and Toth, 2005), which results in deficits in emotion regulation (Brody et al., 2013). This process, in turn, could affect health through chronic release of catecholamines and hormones like cortisol from the hypothalamic–pituitary–adrenal (HPA) axis and the sympathetic-adrenal-medullary systems (Black, 2006). These neurobiological responses to stress that are adaptive under normative conditions of intermittent stress become pathogenic under conditions of chronic or overwhelming stress (Boyce and Ellis, 2005, McEwen, 1998). An additional reason suggested by the biological embedding framework for harsh parenting to affect adolescent's physical health is that harsh parenting lowers cardiovascular reactivity (Johnston-Brooks et al., 1998). A final reason is that harsh parenting is associated with reductions in the children's health-promoting behaviors such as practicing safe sex or abstaining from smoking (Anda et al., 1999, Hillis et al., 2001).
Consistent with these ideas, growing up in a harsh family environment is negatively associated with physical health, growth, and development (Mechanic and Hansell, 1989, Montgomery et al., 1997, Russek and Schwartz, 1997, Stein et al., 1994, Weidner et al., 1992, Williamson et al., 2002), and positively associated with obesity (Siervo et al., 2009). Empirical support for a causal effect of harsh parenting on physical health does not yet include prediction from harsh parenting to changes over time in physical health; this absence is widely acknowledged as a significant limitation of existing research (Berger and Zolotor, 2013, Fergusson et al., 2008; Schafer et al., 2014). The meta-analysis on this area of research conducted by Wegman and Stetler (2009) identified only one prospective longitudinal study, and that did not attempt to predict changes in health (White and Widom, 2003). Without prospective longitudinal tests for a health risk of harsh parenting, the empirical support for this widely-assumed link from harsh parenting to later physical health remains severely limited (Hardt and Rutter, 2004). The current study will also add to the small literature testing for a link between parenting and changes in body mass index (Lane et al., 2013, O'Brien et al., 2007).
In contrast to harsh parenting, warmth and nurturance from close relationships–like the parent-adolescent relationship-promotes physical health (Cohen, 2004). This type of support is believed to reduce the effects of stressful events by promoting less threatening interpretations of those events, as well as more effective coping strategies (Cohen, 2004). This health-protective role of a positive parent-adolescent relationship could manifest in at least two different ways. First, a positive parent-adolescent relationship could improve adolescent health directly (Berkman et al., 2000, Pietromonaco et al., 2013). Alternatively, a positive parent-adolescent relationship could reduce the health risk associated with harsh parenting (a moderating or buffering effect). Our search of the literature identified no examples of a positive relationship with one parent buffering the health risk of harshness by a second parent. However, the framework of Biological Embedding provides several reasons to expect such moderation.
First, adolescents who receive warmth from a parent show greater emotional regulation (Choe et al., 2013, Cummings et al., 2005; Denham et al., 1997; Eisenberg et al., 1998) and lower stress response (Miller et al., 2009), which are putative mechanisms through which harsh parenting could affect physical health. Second, a positive relationship with one parent could create or reinforce the perception that support is available for the adolescent, which may dampen the child's psychological and emotional responses to the stress created by the other parent's harshness (Cohen and Wills, 1985, Wethington and Kessler, 1986). Third, a positive relationship with one parent might also redirect an adolescent's maladaptive behavioral responses (e.g., risky behavior, aggression) to the other parent's harshness (Leidy et al., 2011, Wills and Cleary, 1996). Consistent with this reasoning, research on psychosocial adjustment shows warmth from one parent to buffer the effects of harshness from the other parent (McKee et al., 2007), and for supportive parenting to buffer the effects of family socioeconomic adversity (Pettit et al., 1997). Based on these ideas, we predict that a positive relationship with one parent will buffer the hypothesized health risk of harsh parenting from the other parent.
A final question we address in the current study is that of the nature of any longitudinal link from parenting to adolescent physical health. One possibility is that parenting predicts stable long term changes in physical health. This would be reflected by prediction from parenting to the slope term in a growth model of adolescent health (Singer and Willett, 2003). However, a second possibility is that parenting may show only short-term effects on adolescent health, which would be reflected in prediction by harsh parenting to occasion-specific change, but not to overarching change over time. A third possibility is that the hypothesized influence of parental harshness on short-term changes in health will wane over time, as adolescents move out or in other ways decrease the amount of interaction with their parents. Because failure to specify the effects of short-term change could result in spurious effects for a conventional growth model (Hoffman and Stawski, 2009), we consider all these possibilities.
The current study advances the literature on parenting and physical health in several ways. First, unlike most of the studies on parenting behavior and physical health that rely on one-time simultaneous assessments of previous parenting behavior and current health (Miller et al., 2011), we include longitudinal assessments of health outcomes and observed parenting behaviors. Latent change score models (Ferrer and McArdle, 2010) are used to model both growth (i.e., change in level) and occasion-to-occasion associations (quasi-simplex autoregression) in a single overarching model (Fig. 1). That is, this model allows for the estimation of latent trajectories of health outcomes and for time-varying effects of parenting behavior on change in health outcomes at the true score level (free of measurement error). Second, parenting behavior is frequently assessed via self-reports, the limitations of which could affect reliability, validity, and statistical power (Bailey et al., 2012, Forman et al., 2003, Miller et al., 2011). For example, some of the association between self-reported parent behavior and child health may be attributable to genetic predispositions shared between parents and children (i.e., gene-environment correlation; see Plomin, 1994). Observation based assessments of parent behavior have lower heritability than self-reported assessments of parenting (Kendler and Baker, 2007) making them less subject to such misinterpretation. Third, our focus on the simultaneous, potentially interactive influences of both parents on the adolescent's health more closely reflects the complexity of family system. Fourth, we test for alternative patterns of change over time in adolescent physical health, as well as alternative patterns of prediction from parenting to health over time.
Section snippets
Participants
Data for the present study were collected as part of the Iowa Youth and Families Project (IYFP) an investigation originally focused on the effects of economic hardship on parents and their early adolescents. The current analyses focus on the 451 two-parent families in the IYFP. These families were recruited via telephone through the cohort of all seventh-grade students (ages 12–13) in eight counties in north central Iowa who were enrolled in public or private schools during winter and spring of
Results
Descriptive statistics are presented in Table 1. Adolescent reported physical health at the first assessment had an average of 3.92 and a standard deviation of 0.85. Both self-reported physical health and body mass index showed consistent variability in early to middle adolescence, but adolescents began to diverge in their BMI scores in late adolescence, which is reflected in increasing standard deviations over time.
Discussion
In this study we analyzed change in self-reported physical health and body mass index (BMI) during adolescence. As predicted, adolescents who experience harshness from either parent showed significant decreases in physical health and significant increases in BMI. These differences were not evident at the beginning of adolescence but became evident over time and persisted into young adulthood; they suggest that the associations between parent harshness and adolescent health are not due to
Implications and contributions
One practical implication of these findings is that although interventions often focus on extreme maltreatment and deprivation, harsh parenting may also affect adolescent health. A second point concerns the observed protective effect of warmth from a second parent. This finding echoes results from the developmental psychology literature suggesting that perceiving support from one friend can buffer hostility or bullying from other peers (Adams et al., 2011, Parker and Asher, 1993, Peters et al.,
Acknowledgements
This research is currently supported by a grant from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (HD064687). The content is solely the responsibility of the authors and does not necessarily represent the official views of the funding agencies. Support for earlier years of the study also came from multiple sources, including the National Institute of Mental Health (MH00567, MH19734, MH43270, MH59355, MH62989, MH48165, MH051361), the National Institute on
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