Abuse During Childhood and Biomarkers of Stress-Response in Adulthood

Abstract

A history of child abuse (CA) is associated with a number of leading causes of death and disability in adulthood, and an important mechanism linking CA to such outcomes is the hypothalamic pituitary adrenal (HPA) axis. Biomarkers of its activity are cortisol and its antagonist dehydroepiandrosterone (DHEA), both detectable in hair and saliva, with hair reflecting long-term secretions and saliva reflecting short-term secretions. A commonly cited limitation for the use of hair is the washout of such biomarkers over time in distal segments (>6cm from the scalp). Therefore, in Chapter 1, we evaluated the impact of such washout by comparing distal and proximal segments reflecting the same time period in pregnancy. We found that distal HCC were significantly lower and poorly concordant with proximal HCC, which has methodological implications for researchers interested in using distal hair segments at delivery for their associations with CA history and pregnancy-related outcomes. In Chapter 2, we used non-distal hair segments to evaluate the association between HCC from preconception to the third trimester and measures of stress, including a history of CA. Using linear mixed models, we found no differences in HCC or its patterns according to CA history and observed few differences in HCC across the stress measures overall. Findings suggest that CA may not impact cortisol as measured in hair, or that CA-related dysregulations may be obscured by naturally occurring increases in hair cortisol during pregnancy. In Chapter 3, we examined the relationship between a history of CA and salivary rhythms of cortisol and DHEA in postmenopausal women using piecewise linear mixed models. We found that a history of CA was more consistently associated with dysregulations in DHEA than cortisol, suggesting that CA may impact health in older women via DHEA dysregulations. Ultimately, we hope that the research undertaken in this Dissertation will contribute to the literature attempting to explain the underlying mechanisms linking CA and adverse health outcomes across the life course, and that it be used to advocate for survivors of child abuse and their families.