Theses and dissertations

This collection includes both ASU Theses and Dissertations, submitted by graduate students, and the Barrett, Honors College theses submitted by undergraduate students. 

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Therapeutic neural mechanisms of mindfulness-based therapy in adults with autism

Description
Adults with autism spectrum disorder (ASD) face heightened risk of co-occurring psychiatric conditions, especially depression and anxiety disorders, which contribute to seven-fold higher suicide rates than the general population. Mindfulness-based stress reduction (MBSR) is an 8-week meditation intervention centered around training continuous redirection of attention toward present moment experience, and…

Adults with autism spectrum disorder (ASD) face heightened risk of co-occurring psychiatric conditions, especially depression and anxiety disorders, which contribute to seven-fold higher suicide rates than the general population. Mindfulness-based stress reduction (MBSR) is an 8-week meditation intervention centered around training continuous redirection of attention toward present moment experience, and has been shown to improve mental health in autistic adults. However, the underlying therapeutic neural mechanisms and whether behavioral and brain changes are mindfulness-specific have yet to be elucidated. In this randomized clinical trial, I utilized functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) to characterize fMRI functional activity (Study 1) and connectivity (Study 2) and EEG neurophysiological (Study 3) changes between MBSR and a social support/relaxation education (SE) active control group. Study 1 revealed an MBSR-specific increase in the midcingulate cortex fMRI blood oxygen level dependent signal which was associated with reduced depression. Study 2 identified nonspecific intervention improvements in depression, anxiety, and autistic, and MBSR-specific improvements in the mindfulness trait ‘nonjudgment toward experience’ and in the executive functioning domain of working memory. MBSR-specific decreases in insula-thalamus and frontal pole-posterior cingulate functional connectivity was associated with improvements in anxiety, mindfulness traits, and working memory abilities. Both MBSR and SE groups showed decreased amygdala-sensorimotor and frontal pole-insula connectivity which correlated with reduced depression. Study 3 consisted of an EEG spectral power analysis at high-frequency brainwaves associated with default mode network (DMN) activity. Results showed MBSR-specific and nonspecific decreases in beta- and gamma-band power, with effects being generally more robust in the MBSR group; additionally, MBSR-specific decreases in posterior gamma correlated with anxiolytic effects. Collectively, these studies suggest: 1) social support is sufficient for improvements in depression, anxiety, and autistic traits; 2) MBSR provides additional benefits related to mindfulness traits and working memory; and 3) distinct and shared neural mechanisms of mindfulness training in adults with ASD, implicating the salience and default mode networks and high-frequency neurophysiology. Findings bear relevance to the development of personalized medicine approaches for psychiatric co-morbidity in ASD, provide putative targets for neurostimulation research, and warrant replication and extension using advanced multimodal imaging approaches.
ContributorsPagni, Broc (Author) / Braden, B. Blair (Thesis advisor) / Newbern, Jason (Thesis advisor) / Davis, Mary (Committee member) / Brewer, Gene (Committee member) / Arizona State University (Publisher)
Created2022
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Daily Rumination and Diurnal Cortisol: The Role of Bicultural Competence and Gender

Description

Latinos make up the fastest growing ethnic minority group in the United States and are at higher risk for the developmental of internalizing symptoms in adolescence than other ethnic groups (Merikangas et al., 2010). Rumination has been identified as a transdiagnostic risk factor associated with several internalizing disorders such as…

Latinos make up the fastest growing ethnic minority group in the United States and are at higher risk for the developmental of internalizing symptoms in adolescence than other ethnic groups (Merikangas et al., 2010). Rumination has been identified as a transdiagnostic risk factor associated with several internalizing disorders such as depression, anxiety, and comorbidities of the two (McLaughlin & Nolen-Hoeksema, 2011; Nolen-Hoeksema et al., 2008). Further, indicators of the hypothalamic-pituitary-adrenal (HPA) axis (i.e., flatter diurnal cortisol slopes [DCS] and greater cortisol awakening responses [CAR]) are associated with greater risk of internalizing disorders and chronic stress (Adam et al., 2010; Adam et al., 2017). Notably, no studies have examined the association between rumination and the diurnal cortisol slope in Latino populations, and literature on the relation of rumination and the CAR is mixed (Cropley et al., 2015; Hilt et al., 2017; Zoccola et al., 2011). Leveraging self-reported rumination as well as gold-standard salivary cortisol collection procedures (Stalder et al., 2016), the current study sought to elucidate associations between daily rumination and diurnal cortisol in an adolescent Latino sample by examining gender differences and bicultural competence as potential moderators of this association. Results indicated a significant but small association between night-before rumination on problems/stress and next-day DCS. Further, gender differences were detected in the effects of same-day rumination and the CAR. Greater rumination on feelings was associated with a smaller CAR the same day in males, while greater rumination on problems/stress was linked with a greater CAR the same day in females. In addition, there were no buffering effects of bicultural competence. Findings inform future research regarding potential bidirectional relations of daily rumination and the CAR, as well was how different kinds of daily rumination may have differing associations with the CAR of males and females.
ContributorsTrent, Kevin (Author) / Doane, Leah (Thesis director) / Davis, Mary (Committee member) / Cruz, Rick (Committee member) / Barrett, The Honors College (Contributor) / Department of Psychology (Contributor) / Historical, Philosophical & Religious Studies, Sch (Contributor)
Created2023-05