Poverty is associated with poor physical and emotional development. Activation of the hypothalamic-pituitary-adrenocortical (HPA) axis is argued to be one of the pathways through which poverty acts on these outcomes. While studies of school-aged children have found some evidence for this, there is little evidence for this hypothesis early in development. This may be, in part, because for very young children, the security of their attachment relationships with parents moderates the impact of poverty on HPA axis functioning. The current study investigated the relations between family income as a percentage of the federal poverty limit (FPL), salivary cortisol and attachment (Attachment Q-sort) during well-child checkups with inoculations in 177 toddlers between 12- and 22-months of age. Approximately half of the toddlers were in families living below 150% FPL, with 47% of these classified as securely attached, compared to 72% of toddlers in families living above 150% FPL. Cortisol levels increased in response to the inoculation and this did not differ by poverty or attachment security. Overall, however, beginning at clinic arrival toddlers in families living below 150% FPL who had an insecure attachment had significantly higher cortisol compared to toddlers living in poverty or near poverty with secure attachments. This finding held when we removed toddlers with high levels of negative life events in their families and primary caregivers who exceeded the screening cutoff for depressive symptoms. Thus, attachment was a significant moderator of the association between poverty and HPA axis activity, with significant implications for screening and referral of caregiving dyads at risk.
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The authors would like to thank the patients, families, providers and medical staff at the Children’s Minnesota clinics without whom this research would not have been possible, Lea Neumann for assisting with data collection, and Christina Stolz for database preparation. The research was supported by The JPB Research Network on Toxic Stress , a project of the Center on the Developing Child at Harvard University.
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