Wednesday, September 14, 2016

A psychological mechanism to explain why childhood adversity diminishes adult health?

A large number of studies have by now shown that harsh social and physical environments early in life are associated with a substantial increase in the risk of chronic illnesses, such as heart disease, diabetes, and some forms of cancer. It is generally assumed that the hypothalamic-pituitary-adrenal (HPA) axis is an essential biological intermediary of these poor health outcomes in adulthood. Zilioli et al. suggest that lowered sense of self worth is the psychological mechanism that persists into adulthood to alter stress physiology. Their abstract:
Childhood adversity is associated with poor health outcomes in adulthood; the hypothalamic-pituitary-adrenal (HPA) axis has been proposed as a crucial biological intermediary of these long-term effects. Here, we tested whether childhood adversity was associated with diurnal cortisol parameters and whether this link was partially explained by self-esteem. In both adults and youths, childhood adversity was associated with lower levels of cortisol at awakening, and this association was partially driven by low self-esteem. Further, we found a significant indirect pathway through which greater adversity during childhood was linked to a flatter cortisol slope via self-esteem. Finally, youths who had a caregiver with high self-esteem experienced a steeper decline in cortisol throughout the day compared with youths whose caregiver reported low self-esteem. We conclude that self-esteem is a plausible psychological mechanism through which childhood adversity may get embedded in the activity of the HPA axis across the life span.
And, a clip from their discussion, noting limits to the interpretation of the correlations they observe:
These findings suggest that one’s sense of self-worth might act as a proximal psychological mechanism through which childhood adversity gets embedded in human stress physiology. Specifically, higher self-esteem was associated with a steeper (i.e., healthier) cortisol decline during the day, whereas low self-esteem was associated with a flatter cortisol slope. Depression and neuroticism were tested as alternative pathways linking childhood adversity to cortisol secretion and were found not to be significant, which suggests that the indirect effect was specific to self-esteem. Nevertheless, it is plausible that other psychological pathways exist that might carry the effects of childhood adversity across the life span. For example, attachment security, a potential antecedent of self-esteem that forms during childhood, would be a strong candidate for playing such a role. Unfortunately, this construct was not assessed in our studies, but we hope that future work will test this hypothesis.

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