Toxic Stress and Protective Factors in Multiethnic School-Age Children

Sunday, 30 July 2017

Eileen M. Condon, MSN
Yale School of Nursing, Yale University, Orange, CT, USA


 Exposure to stress in early childhood is associated with poor health and developmental outcomes that extend across the lifespan (McEwen, 2008a). To explain this link, researchers have proposed a conceptual taxonomy consisting of three types of stress response in early childhood: positive stress, tolerable stress, and toxic stress (Shonkoff et al., 2012). The most potent stress response, toxic stress, results from exposure to chronic stressors such as poverty, violence, or parental mental illness. Without the protection of a nurturing caregiver, this exposure can result in persistent elevation of the child’s stress response system, and in turn impair brain development and contribute to disruption in the neuroendocrine, immune, metabolic and cardiovascular systems (Juster, McEwen, & Lupien, 2010; McEwen, 2008b). These physiological disruptions are associated with poor long-term health and behavioral outcomes, including growth delay, obesity, depression, alcoholism, and cardiovascular disease (Garner, 2013). Identifying factors that protect against toxic stress is of significant importance to nursing research and clinical practice, as toxic stress prevention is essential for health promotion, disease prevention, and reduction of health disparities among families at risk.

 Although toxic stress is a metaphor that cannot be empirically measured, examining the physiological, health, and behavioral outcomes associated with chronic stress exposure in childhood may provide important insight into the mechanisms through which toxic stress can be prevented. Studies of animals and maltreated children demonstrate that supportive caregiving can buffer against exposure to chronic stress, but the specific positive caregiving patterns that best protect children against chronic stress are poorly understood (Hostinar, Sullivan, & Gunnar, 2014). Past maternal experiences and maternal mental health can also impact the caregiver-child relationship, but the relationship between these maternal characteristics and indicators of exposure to chronic stress in children remain largely unexplored (Goodman et al., 2011). Racial discrimination can also be a significant source of stress for racial and ethnic minority families, but the relationships among maternal experiences of racism, racial socialization parenting behaviors, and indicators of exposure to chronic stress in children have not been examined (Yasui, 2015). Therefore, the purpose of this study is to describe and examine associations among maternal characteristics (past maternal experiences and maternal mental health), maternal caregiving patterns, and indicators of exposure to chronic stress in a multiethnic, urban sample of mothers and children at early school age (4-9 years).

 This study is framed by the ecobiodevelopmental (EBD) model, which guides understanding of the link between early childhood adversity and lifelong health via the toxic stress response. Within this framework, a child’s biology interacts with the early social environment to influence long-term health and development (Shonkoff et al., 2012).


 This ongoing descriptive study employs a cross-sectional design and includes a sample of maternal-child dyads living in socioeconomically disadvantaged neighborhoods in New Haven, Connecticut. Families in the sample are anticipated to primarily self-identify as Latina and Black, and the targeted sample size is 58 dyads. Families are eligible for inclusion if the child is between 4-9 years of age and the child’s mother has regular contact with the child. Maternal variables include past maternal experiences (adverse childhood experiences, family strengths, experiences of discrimination), maternal mental health (PTSD symptoms), and current caregiving patterns (parental reflective functioning, parenting behaviors, racial socialization behaviors). Child variables include neuroendocrine functioning (hair cortisol), immune functioning (salivary cytokines and c-reactive protein), cardiovascular functioning (blood pressure), health (body mass index, growth delay, health history), behavior (internalizing/externalizing behaviors), and learning (school performance). At the completion of data collection, univariate statistics will be used to describe maternal characteristics, maternal caregiving patterns, and child indicators of exposure to chronic stress in the sample population. Bivariate analyses will be used to examine the strength and direction of relationships between the maternal and child variables.


 Completion of data collection is expected in Spring 2017. Preliminary descriptive results will be presented, with a focus on associations among maternal protective factors and physiological indicators of exposure to chronic stress in children.

 This study is innovative in its use of biological outcome measures to explore the effects of maternal protective factors within families at risk for toxic stress. However, physiological indicators of toxic stress are poorly defined in the literature, and thus biomarkers for the current study were selected based on available knowledge and feasibility. Another limitation is the study’s small sample size, which may not be adequate to use multivariate statistical methods to study the relationships between variables. However, it is expected that this exploratory study will provide an important foundation for future research on toxic stress and protective factors in young children at risk.


 Given the cascade of poor outcomes associated with toxic stress, there is a pressing need to understand the mechanisms through which toxic stress can be prevented in early childhood. The results of this study will lay important groundwork for future nursing research studies focused on promoting health and reducing disparities in vulnerable families at risk for toxic stress. The findings of this study will also make a valuable contribution to nursing clinical care, as the protective caregiving strategies identified can be encouraged both in the primary care setting and as part of in-depth interventions. Furthermore, identifying links among maternal characteristics, current caregiving patterns, and indicators of exposure to chronic stress in children may play an important role in the development of social and economic policies that reduce maternal stressors, promote family strengths, prevent intergenerational transmission of trauma, and empower socioeconomically disadvantaged communities.