Effects of a therapeutic intervention for foster preschoolers on diurnal cortisol activity
Introduction
Alterations in hypothalamic–adrenal–pituitary (HPA) axis activity (as measured by salivary cortisol activity) have been observed in children following a range of adverse early life experiences. For example, atypical patterns of HPA axis activity have been reported in children who experienced the early loss of a caregiver (Meinlschmidt and Heim, 2005), in children who were maltreated in their family of origin (De Bellis et al., 1999; Shea et al., 2004), and in children who were subjected to severe neglect as a result of institutional rearing in developing countries (Carlson and Earls, 1997). The characteristic pattern of alterations noted for these children is a flattening of diurnal (morning-to-evening) cortisol activity, owing largely to low early-morning cortisol levels (Gunnar and Vazqeuz, 2001). Similar patterns associated with chronic stress have been noted in adults (Heim et al., 2000), and it is presumed that these flattened or hypoactive patterns reflect downregulation of the HPA axis following periods of heightened activity early in life (Friese et al., 2005).
Animal models of early adverse experiences have provided evidence that manipulations affecting the development and functioning of the HPA axis operate, at least in part, via their impact on maternal care (Smotherman and Bell, 1980). In rodents, manipulations impacting the dam's licking and grooming of her pup have shown long-term effects on HPA axis reactivity and regulation; similar results were found when dams characteristically provided high or low levels of licking and grooming (Meaney and Szyf, 2005). In non-human primates, manipulations that disrupt the mother–infant relations—including maternal deprivation and repeated separation—produce offspring that are behaviorally vulnerable to stressors (Suomi, 1997; Levine, 2005). In several recent studies of rhesus infants reared under conditions of maternal deprivation or repeated, unpredictable maternal separations, researchers have reported atypical diurnal cortisol activity resulting particularly from low early-morning cortisol levels (Boyce et al., 1995; Sánchez et al., 2005). These animal data suggest that circumstances that limit a caregiver's ability to serve as an external source of affective and physiological regulation during critical points in development impact the development of the HPA axis. Moreover, these studies have implications for understanding how disturbances in the caregiving system during early human development might impact the developing child (Heim and Nemeroff, 2001; Gunnar et al., 2006).
The association between disruptions in maternal care and altered HPA axis activity might be particularly relevant for foster children. Several recent studies have shown that, like other maltreated children and children reared in neglectful institutional care, foster children show atypical diurnal cortisol activity. These patterns often involve very low early-morning cortisol levels with little change from morning to evening. For example, Dozier et al. (2006) reported smaller morning-to-evening cortisol changes in a sample of 55 foster children (placed in care in infancy) relative to a non–foster care sample. Similarly, Fisher et al. (2006) documented that a significantly greater proportion of foster preschoolers entering new placements had very low early-morning cortisol levels compared to a non–foster care sample of comparable socioeconomic class. Consistent with the hypothesis that disruptions in caregiving might mediate these effects, there is emerging evidence (Bruce et al., 2007) that foster children who exhibit extremely low early-morning cortisol levels are likely to have experienced more severe neglect and more foster placement disruptions during infancy and toddlerhood compared to those with more typical early-morning cortisol levels.
Inasmuch as there are over 500,000 foster children in the United States (US Department of Health and Human Services, 2006), issues surrounding altered HPA axis activity and the associated symptoms of anxiety and affective dysregulation in foster children could have considerable public health implications. Numerous studies have documented exceptionally high risk for poor outcomes in this population. For example, foster children have been found to exhibit very high rates of psychiatric symptoms and mental disorders (Landsverk et al., 2001), substance abuse (Hurlburt et al., 2004), poor academic outcomes (Fanshel, 1978; Wodarski et al., 1990; Stock and Fisher, 2006), and physical growth retardation (Wyatt et al., 1997; Pears and Fisher, 2005). Increased understanding about the associations between specific dimensions of early stress, alterations in HPA axis activity, and negative outcomes has the potential to clarify explanatory models regarding risk and protection in foster children.
In addition, there is a need to better understand the limits of HPA axis plasticity following exposure to early adversity. Although this is a relatively new line of inquiry, converging sources of evidence have suggested that the HPA axis remains mutable over time and could be impacted by therapeutic interventions and other environmental changes. First, studies of rodents exposed to “enriched environments” following early adversity have shown improved neural development (e.g., greater synaptic density; Turner and Greenough, 1985), although the data on whether enriched environments lead to more typical neuroendocrine functioning are equivocal (Moncek et al., 2004). Second, psychotherapeutic treatment studies on adult human populations (with and without psychopathology) have shown similar improvements in HPA axis functioning. For example, Mommersteeg et al. (2006a) examined diurnal cortisol levels in a psychotherapy treatment study of adults with burnout following chronic stress exposure. Compared to the healthy adults from the comparison group, the adults in the treatment group exhibited lower pretreatment early-morning cortisol levels that increased significantly following 14 treatment sessions. Similarly, several studies have documented the positive effects of stress management interventions in reducing healthy individuals’ cortisol responses to acute stressors (Gaab et al., 2003, Gaab et al., 2006; Hammerfald et al., 2005). Third, in a series of studies on children adopted in the United States following institutional rearing in developing nations, researchers have documented low early-morning cortisol levels at the time of adoption that became more typical (i.e., having a morning peak in cortisol that declines gradually through the day) after time in the adoptive families (Bruce et al., 2000; Gunnar et al., 2001). The evidence from these three sources supports the idea that therapeutic interventions might have the potential to impact HPA axis functioning in children following exposure to early stress.
In the present study, we examined whether foster preschoolers randomly assigned to a therapeutic family-based intervention would develop more typical diurnal cortisol activity over time compared to foster preschoolers randomly assigned to regular foster care. Typical diurnal cortisol activity was defined by comparing children in both foster care groups to a group of same-aged, non-maltreated, low-income community children. The intervention (described below) has been documented to reduce the risk for failed adoptions or reunifications with birth parents following foster care, particularly when multiple prior foster placements are involved (Fisher et al., 2005). To examine changes in diurnal cortisol activity, we tracked monthly early-morning and evening cortisol levels over 12 months following a new foster placement.
It is important to note that the focus of the current study was on only one component of HPA axis functioning: basal diurnal cortisol activity. There is a vast literature involving human and animal studies focusing on the responsiveness of the HPA axis to laboratory-induced and naturally occurring stressors. We chose to focus on basal activity for several reasons. First, as is noted above, alterations in this area of HPA functioning have been observed among foster children and similar human and animal populations with early disruptions in maternal care. Second, no reports in the literature have shown laboratory-induced social stressors to reliably produce HPA axis activity in preschoolers. Third and finally, there are ethical concerns with using social or physical stressors in this vulnerable population.
Section snippets
Participants
The sample was comprised of 3–6-year-old foster preschoolers entering new placements (N=117) under the care of a public child welfare agency in a Pacific Northwest city with a population of about 150,000. To be eligible for the study, the placement had to be expected to last for at least 3 months. Recruitment occurred continuously over 3.5 years.
Eligible participants were randomly assigned to the Multidimensional Treatment Foster Care for Preschoolers (MTFC-P) intervention condition or to a
Results
The means and standard deviations for monthly AM–PM cortisol change, AM cortisol level, and PM cortisol level by group are shown in Table 1.
Discussion
This study addressed two interrelated questions regarding the effects of a therapeutic parenting intervention on diurnal cortisol levels in foster preschoolers: whether it could impact diurnal cortisol activity following exposure to early adversity (including neglect, maltreatment, and relationship disruption) and, if so, whether it could improve diurnal cortisol activity by increasing AM cortisol levels. The growth modeling analyses provided fairly unequivocal support for the hypothesis that
Role of the funding sources
NIH provided funding but played no other role in the research.
Conflict of interest
Dr. Fisher is a partner in Treatment Foster Care Consultants, LLC, which provides consultation on the implementation of the MTFC-P intervention in community settings.
Acknowledgments
Support for this research was provided by the following grants: R01 MH059780 and R01 MH065046, NIMH, US PHS; R01 HD045894, NICHD, US PHS; P20 DA017592, NIDA, US PHS; and P30 MH046690, NIMH and ORMH, US PHS. The authors wish to express appreciation to Seymour Levine and Hyoun Kim for their contributions to this manuscript; to members of the Early Experience, Stress Neurobiology, and Prevention Science Network for support and mentorship; to Kristen Greenley, Karla Antoine, Kim Bronz, and the
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Cited by (0)
- 1
Now at the Department of Sociology, Brigham Young University, 2008 Joseph F. Smith Building, Provo, UT 84602, USA.
- 2
Now at the Center on Teaching and Learning, 5292 University of Oregon, Eugene, OR 97403-5292, USA.