UMD Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/3
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.
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Item Effects of early and concurrent parenting and child cortisol reactivity on hippocampal structure and functional connectivity during childhood: A prospective, longitudinal study(2017) Blankenship, Sarah Louise; Dougherty, Lea R; Riggins, Tracy; Neuroscience and Cognitive Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Offspring of depressed mothers are at increased risk for emotional and behavioral disorders and social impairment. One proposed mechanism of risk transmission is through exposure to maladaptive parenting styles, as depressed mothers display higher levels of hostility and lower levels of support than non-depressed mothers. Rodent models indicate that the early parenting environment programs the endogenous stress response system, the hypothalamic-pituitary-adrenal (HPA) axis, through a cascade of epigenetic processes, ultimately elevating levels of glucocorticoid stress hormones (i.e., cortisol in humans). Elevated cortisol levels have been linked to both structural and functional changes in the hippocampus, a medial temporal lobe structure implicated in regulation of the HPA axis and the pathophysiology of depressive disorders. Despite elucidation of the pathways through which parenting influences neurobiological development in rodents, research examining these associations in humans is only emerging. The present study aimed to translate the rodent literature by examining the effects of early and concurrent parenting on hippocampal structure and functional connectivity during childhood, with a specific emphasis on exploring the mediating role of cortisol reactivity, in a longitudinal sample of offspring of depressed mothers and a community comparison group. At 3-6 and 5-10 years, observational measures of parenting and children’s salivary cortisol responses to a laboratory stressor were assessed. At 5-10 years, children completed structural and resting-state functional MRI scans. Findings revealed timing- and region-dependent associations. Early positive parenting predicted larger hippocampal head volumes whereas concurrent positive parenting predicted smaller body volumes. Early cortisol reactivity predicted larger body volumes whereas concurrent cortisol reactivity predicted smaller tail volumes. Concurrent parenting (positive and negative) predicted hippocampus subregion connectivity with regions of the cerebellum. Early cortisol reactivity predicted increased hippocampal connectivity with the cuneus and regions of the cingulate gyrus. There was a significant indirect effect of greater T1 Negative Parenting on smaller left hippocampal tail volume through increased concurrent cortisol reactivity. Significant interactions with maternal depression were also observed. This research provides a necessary translation of the rodent literature and elucidates possible timing-dependent neurobiological pathways through which early experience may confer increased risk for poor outcomes in human offspring.Item Cortisol Reactivity and Observed Parenting among Mothers of Children with and without ADHD(2015) Thomas, Sharon Renee; Chronis-Tuscano, Andrea; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Parenting is a robust predictor of developmental outcomes among children with ADHD. Early parenting predicts the persistence and course of ADHD and comorbid problems above and beyond risk associated with shared genetic effects. Yet, on average, mothers of children with ADHD are less positive and more negative in their parent-child interactions compared to mothers of non-disordered children. Little is known about psychobiological markers which may be associated with individual variations in maternal parenting in families of children with ADHD. Neurobiological models of parenting suggest that maternal cortisol levels following a stressor may be positively associated with hostile and intrusive parenting; however, to date no studies have examined maternal cortisol reactivity and parenting in school-age, or clinical samples of, children. Mothers’ regulation of physiological stress responses may be particularly important for families of children with ADHD, as parenting a child with chronically challenging behaviors represents a persistent environmental stressor. The current study sought to extend the existing literature by providing an empirical examination of the relationship between maternal cortisol reactivity following two laboratory stressors and parenting among mothers of children with and without ADHD. It was hypothesized that child ADHD group would moderate the relationship between cortisol reactivity and self-reported and observed parenting. Greater total cortisol output and greater increase in cortisol during the TSST were associated with decreased positive parenting and increased negative and directive parenting, with the exception of parental involvement, which was associated with increased cortisol output during the TSST. Conversely, cortisol output during the PCI was associated with increased positive parenting, increased parental involvement, and decreased negative parenting. In contrast to the TSST, a greater decrease in cortisol during the PCI indicated more positive parenting and parental involvement. These associations were specific to mothers of children with ADHD, with the exception of maternal directiveness, which was specific to comparison mothers. Findings add to our understanding of physiological processes associated with maternal parenting and contribute to an integrative biological, psychological, and cognitive process model of parenting in families of children with ADHD.Item Stability and Change of Cortisol Reactivity to a Laboratory Stressor from Early to Middle Childhood(2015) Leppert, Katherine A.; Dougherty, Lea R; Psychology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This study examined the stability and change of children’s cortisol reactivity to a laboratory stressor from early to middle childhood and moderators of change. Ninety-six children completed stress-inducing laboratory tasks and provided five salivary cortisol samples at preschool age (T1; M = 49.88 months, SD = 9.51 months) and three years later (T2; M = 87.44 months, SD = 11.42 months). At T1, parents completed clinical interviews assessing child and parent psychopathology. Cortisol reactivity patterns significantly changed from decreasing to increasing reactivity from early to middle childhood. Moreover, preschool psychopathology moderated this change. Children with fewer preschool psychiatric symptoms demonstrated more stable reactivity patterns, whereas children with preschool psychiatric comorbidity demonstrated more unstable reactivity patterns across assessments. Findings suggest a developmental shift from decreasing to increasing cortisol reactivity from early to middle childhood, and highlight early preschool psychopathology as a moderator of change in cortisol reactivity.