The human stress response has been shaped by natural selection to manage acute environmental challenges. While short-term activation of this response is imperative for survival, its chronic stimulation can lead to negative health consequences due to dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis and its end product, the glucocorticoid cortisol. In fact, chronic psychosocial stress has been identified as an important pathway through which lifestyle alterations associated with market integration (MI; the degree of production for and consumption from a market-based economy) impact traditionally-living societies experiencing rapid cultural changes. Few studies, however, have systematically examined the relationships between MI and HPA axis activity. Moreover, limited research has examined how factors associated with MI influence children's perceptions of the shifting cultural milieu. The primary goal of this dissertation was to illuminate the dynamic features of the human stress response among the indigenous Shuar of Amazonian Ecuador with four objectives: 1) To examine HPA axis activity among the Shuar to address fundamental questions about the basic biological mechanisms of the human stress response; 2) To examine individual differences in HPA axis activity as shaped by age, sex, and body mass index (BMI); 3) To evaluate how factors associated with MI influence the HPA axis activity of Shuar children and adolescents; and 4) To utilize a conceptual model (cultural consonance) to better understand how Shuar youth perceive changes in the sociocultural environment. Results suggested that age was positively associated with cortisol levels, while age and sex moderated the relationship between BMI and the decline in cortisol across the day. Factors associated with MI did not directly affect the cortisol patterns of Shuar children and adolescents; however, age, sex, and BMI moderated these relationships. For example, Shuar youth experiencing greater exposure to MI displayed age-related increases in waking cortisol levels. Finally, Shuar children and adolescents with less exposure to MI demonstrated more incongruity with their locally-defined model of lifestyle success due to limited access to items identified as important for “a good life”. These studies illustrate the complexity of the human stress response in the context of culture change. This dissertation includes unpublished, co-authored materials. / 10000-01-01

Relationship conflict is robustly linked to negative physiological responses that have serious implications for partners’ overall physical health. The link between relationship conflict and physiological reactivity, however, has been studied almost exclusively in a laboratory setting. The first aim of this study was to assess the link between conflict and physiological function in couples’ home environments. Newlywed spouses reported occurrences of marital conflict in a daily diary and concurrently provided morning and evening saliva samples for the calculation of daily diurnal cortisol slopes. Spouses experienced less steep (i.e., less healthy) diurnal cortisol slopes on days of greater marital conflict. The second aim of this study was to examine whether spouses’ connections with close others outside their marriages (i.e., quantity and quality of perceived network support) moderate physiological responses to marital conflict. Whereas the quantity of network support did not influence spouses’ responses to conflict, the quality of spouses’ network support attenuated the association between daily marital conflict and diurnal cortisol. Specifically, whereas those spouses who were less satisfied with their network support experienced less steep diurnal cortisol on days of greater marital conflict, those spouses who were more satisfied with their network support exhibited no effects of daily marital conflict on diurnal cortisol. Implications for maintaining quality social relationships outside a marriage are discussed. / text

abstract: Stress in individuals presents in various forms and may accumulate across development to predict maladaptive physical and psychological outcomes, including greater risk for the onset of internalizing symptoms. Early life stress, daily life experiences, and the stress response of the hypothalamic-pituitary-adrenal (HPA) axis have all been examined as potential predictors of the development of psychopathology, but rarely have researchers attempted to understand the covariation or interaction among these stress domains using a longitudinal design when looking at the influence of stress on internalizing psychopathology. Further, most research has examined these processes in adulthood or adolescence with much less attention given to the influence of these dynamic stress pathways in childhood. Guided by the biopsychosocial model of stress, this study explored early life stress, daily life stress, diurnal cortisol (cortisol AM slope), and internalizing symptoms in a racially/ethnically and socioeconomically diverse sample of twins participating in an ongoing longitudinal study (N=970 children; Arizona Twin Project; Lemery-Chalfant et al. 2013). An additive model of stress and a stress sensitization framework model were considered as potential pathways of stress to internalizing symptoms in middle childhood. Based on a thorough review of relevant literature, it was expected that each stress indicator would individually predict internalizing symptoms. It was also predicted that early life stress would moderate the associations between diurnal cortisol and internalizing symptoms, as well as daily life stress and internalizing symptoms. Multilevel modeling analyses showed that early life stress and cortisol AM slope, but not daily life stress, predicted internalizing symptoms. Early life stress did not moderate the associations between daily life stress and internalizing symptoms or cortisol AM slope and internalizing symptoms. Results support independent additive contributions of both physiological stress processes and early life parental stressors in the development of internalizing symptoms in middle childhood. Future investigation is needed to better understand the sensitizing effects of early parental life stress during this developmental stage. / Dissertation/Thesis / Masters Thesis Psychology 2020

abstract: Built upon Control Value Theory, this dissertation consists of two studies that examine university students’ future-oriented motivation, socio-emotional regulation, and diurnal cortisol patterns in understanding students’ well-being in the academic-context. Study 1 examined the roles that Learning-related Hopelessness and Future Time Perspective Connectedness play in predicting students’ diurnal cortisol patterns, diurnal cortisol slope (DS) and cortisol awakening response (CAR). Self-reported surveys were collected (N = 60), and diurnal cortisol samples were provided over two waves, the week before a mid-term examination (n = 46), and the week during students’ mid-term (n = 40). Using multi-nomial logistic regression, results showed that Learning-related Hopelessness was not predictive of diurnal cortisol pattern change after adjusting for key covariates; and that Future Time Perspective Connectedness predicted higher likelihood for students to have low CAR across both waves of data collection. Study 2 examined students’ future-oriented motivation (Future Time Perspective Value) and socio-emotional regulation (Effortful Control and Social Support) in predicting diurnal cortisol patterns over the course of a semester. Self-reported surveys were collected (N = 67), and diurnal cortisol samples were provided over three waves of data collection, at the beginning of the semester (n = 63), during a stressful academic period (n = 47), and during a relaxation phase near the end of the semester (n = 43). Results from RM ANCOVA showed that Non-academic Social Support was negatively associated with CAR at the beginning of the semester. Multi-nomial logistics regression results indicated that Future Time Perspective Value and Academic Social Support jointly predicted CAR pattern change. Specifically, the interaction term marginally predicted a higher likelihood of students switching from having high CAR at the beginning or stressful times in the semester to having low CAR at the end the semester, compared to those who had low CAR over all three waves. The two studies have major limits in sample size, which restricted the full inclusion of all hypothesized covariates in statistical models, and compromised interpretability of the data. However, the methodology and theoretical implications are unique, providing contributions to educational research, specifically with regard to post-secondary students’ academic experience and well-being. / Dissertation/Thesis / Doctoral Dissertation Family and Human Development 2017