Browsing by Subject "HPA Axis"

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    The Effects of Child Maltreatment, Genetic Factors, and HPA Axis Functioning on Internalizing Symptoms in African American Children: A Moderated Mediation Model
    (2017-08) VanZomeren, Adrienne
    Child maltreatment is a potent relational pathogen that alters functioning across diverse developmental domains, and has been shown to increase risk for a host of mental health problems, including internalizing disorders. Similarities in the neuroendocrine profiles of individuals who develop internalizing symptoms and individuals who have been maltreated are striking, and suggest a role of neuroendocrine functioning, specifically the hypothalamic-pituitary-adrenal (HPA) axis, in the pathogenesis of internalizing disorders following child maltreatment. Risk and protective genetic factors, particularly relevant to HPA axis functioning, have been discovered, further highlighting involvement of the HPA axis and offering ideas about how some maltreated children may evade the biological impact of maltreatment. There has been movement in the field toward identifying mediators and moderators at multiple levels of analysis to best inform developmental mechanisms, which may ultimately aid in the treatment and prevention of deleterious outcomes following child maltreatment. Utilizing a large, ethnically homogenous sample, the current study employed exploratory and confirmatory factor analysis and structural equation modeling to examine associations among child maltreatment, risk across multiple HPA-related genes, daytime cortisol patterns, and internalizing symptoms in effort to clarify biological mechanisms. Results revealed that experiences of maltreatment prior to age 5 were most predictive of internalizing symptoms in African American youth, whereas maltreatment occurring at or after age 5 was most predictive of HPA axis dysregulation in the form of blunted diurnal decrease of cortisol. Genetic factors did not alter the relationship between maltreatment and cortisol, nor were genetic risk patterns reflected in HPA functioning. There was no mediation of the relationship between maltreatment and internalizing symptoms by HPA dysfunction. Results are interpreted through a developmental psychopathology lens, emphasizing the principle of equifinality, whereby children follow multiple pathways toward internalizing symptoms. Implications for future research, particularly the need for longitudinal studies in this area, are discussed.
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    Interplay Between Frontolimbic Resting State Connectivity And Hypothalamic-Pituitary-Adrenal Axis Functioning In Adolescents With And Without Depression
    (2019-03) Thai, Michelle
    Depression is associated with abnormalities in HPA-axis functioning and neural circuitry that underlie the stress response. Although positive associations have been found between cortisol levels and amygdala metabolism, activation, and volume, the associations between cortisol and resting state functional connectivity (RSFC) has not been examined. RSFC captures intrinsic connections between brain regions that may set the stage for the rallying of the HPA system. The association between frontolimbic RSFC in particular and HPA axis functioning is critical since stress system functioning involves activating to and recovering from threat, processes mediated by limbic and prefrontal activity respectively. The purpose of this study was to examine the association between cortisol and frontolimbic RSFC in healthy controls and adolescents with depression. Overall, healthy controls tended to show positive correlations between frontolimbic connectivity and cortisol levels in the context of the TSST whereas patients with depression showed an inverse relationship. Positive association between neural and HPA stress systems in healthy controls may suggest coordinated upregulation and downregulation of these two stress systems in response to stress. In contrast, in patients with depression, excessive recruitment of the mPFC by the amygdala may interfere with HPA system recruitment efficiency and successful rallying of HPA axis in response to social stress. These findings provide evidence that the intrinsic quality of this frontolimbic channel is related to HPA axis functioning, and patients with MDD show different patterns of associations compared to HC, which may interfere with adaptive stress functioning.