Theses and Dissertations at Montana State University (MSU)
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Item The impact of trait anxiety and psychosocial stress on sympathetic neural control in humans(Montana State University - Bozeman, College of Letters & Science, 2023) Bigalke, Jeremy Andrew; Chairperson, Graduate Committee: Cara A. Palmer; This is a manuscript style paper that includes co-authored chapters.Anxiety is highly prevalent, and while it is often adaptive, excessive stress and anxiety may predispose individuals to a heightened risk of cardiovascular disease. While excessive activity of the sympathetic nervous system (SNS) may underlie this association, direct measures of muscle sympathetic nerve activity (MSNA) indicate little, if any, alterations in resting sympathetic outflow in individuals with anxiety disorders. Assessment of the relationship between trait anxiety, MSNA, and blood pressure using a large cohort of healthy adults has not yet been conducted. Further, utilization of stress tasks within microneurographic settings that minimize the potential influence of breathing alterations, muscle movement, and other variables on the typically observed inter-individual variability in MSNA responsiveness to mental stress are needed to adequately assess the sole contribution of psychological stress on sympathetic neural activity. In Study 1, the association between trait anxiety, MSNA, and resting blood pressure was assessed in a population of 88 healthy adults, representing the largest study to date pairing trait anxiety with directly recorded sympathetic outflow to the periphery. Our findings indicate an independent relationship between trait anxiety, MSNA, and blood pressure when controlling for both age and sex. In Study 2, we utilized the trier social stress test (TSST) to assess the impact of anticipatory stress on MSNA and blood pressure in 28 healthy adults. Our findings showed that anticipatory stress is associated with increased blood pressure and reduced MSNA. Additionally, this appears to be baroreflex mediated as the magnitude of changes in blood pressure were directly proportional to reductions in MSNA, a relationship that was weakened or nonexistent during the active speech portion of the task. Lastly, anticipatory MSNA responsiveness accurately predicted reactivity to subsequent stress tasks. Together, these studies highlight a key relationship between both chronic, and acute psychological stress and anxiety on sympathoneural function in healthy adults.Item Early family environments and memory: the role of physiological and psychological responses to acute stress(Montana State University - Bozeman, College of Letters & Science, 2020) Counts, Cory; Chairperson, Graduate Committee: Neha John-HendersonChildhood family environments have important implications for outcomes in adulthood. Specifically, the experience of adversity in childhood is related to numerous maladaptive outcomes later in life. It is currently unknown how early adversity affects memory consolidation and processing. Previous research has established an association with anxiety and depression possessing a negative memory bias. A negative memory bias is defined as attentional and perceptual favor towards information that is contextually negative or threatening. Research has not examined the relationship between negative memory bias and childhood adversity after the induction of stress. Stress has previously shown to be disruptive to memory outcomes. Further, a growing body of research has shown that early childhood adversity associates with blunted physiological responses to stress. It is possible that through the pathway of blunted reactivity, early childhood adversity associates with negative memory bias. To test these hypotheses, a sample of college students (N=64) studied a 50-word list that included 25 emotionally negative words and 25 emotionally neutral words. Participants then completed the Trier Social Stress Test, an evaluative stressor well known for inducing stress. After the stress task, participants were asked to freely recall words they previously studied. Results showed that higher ratings or risk and emotional abuse in childhood associated with increased negative word recall. The relationship was partially mediated through blunted heart rate reactivity to the stress task. Implications and future directions are discussed.Item Changes in task performance as a result of stress(Montana State University - Bozeman, College of Letters & Science, 1975) Brown, Scott Wilson