Psychiatry - Theses
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ItemAssociations between early adversity, brain development, and mental health during adolescence( 2022)Early adverse experiences, like childhood maltreatment and socioeconomic disadvantage, are associated with lifelong consequences for mental health. However, the underlying neurobiological mechanisms of these associations are yet to be characterized. It has been suggested that adverse experiences may shape mental health via alterations in neurodevelopment. The aim of this thesis was to investigate how childhood maltreatment and socioeconomic disadvantage (which are both highly prevalent in the general community and are strong predictors of poor mental health outcomes), influence brain development during childhood and adolescence, and how those changes, in turn, contribute to mental health outcomes. An additional aim of the thesis was to examine environmental and psychological factors that may buffer the effects of adversity on brain development and mental health. This thesis used structural magnetic resonance imaging and resting state functional magnetic resonance imaging data from two studies, the Orygen Adolescent Development Study, and the Adolescent Brain Cognitive Development Study, in order to comprehensively characterize associations between childhood maltreatment, socioeconomic status (SES), and brain structure and functional connectivity as well as mental health. In the first and second study we investigated associations between childhood maltreatment (as well as specific dimensions of maltreatment) and longitudinal development of functional connectivity during adolescence, and showed that total maltreatment, abuse, and neglect, are associated with deviations in typical patterns of functional connectivity development. We also showed that these alterations in functional connectivity development are associated with mental health outcomes. Next, in the third study, we systematically synthesized the association between SES and brain structure, function, and connectivity, and showed that while there were some consistencies in findings, results were often mixed (especially at the level of individual SES indices). In the fourth and fifth study, we focused specifically on neighborhood disadvantage given that our review (third study) identified this to be a relatively unexplored SES indicator. In the fourth study, we showed that neighborhood disadvantage is associated with longitudinal alterations in brain-predicted-age trajectory, which was found to be moderated by temperamental effortful control. In the sixth study, we demonstrated cross-sectional alterations in functional connectivity as a function of disadvantage. We also showed that some of these alterations were associated with poor mental health. However, some associations between neighborhood disadvantage and functional connectivity were found to be moderated by positive parenting and favorable school environments. Finally, in studies six and seven, we demonstrate the independent and interactive effects of different SES indicators on brain structure and connectivity. We show that household income moderated the association between neighborhood disadvantage/low parent educational attainment and connectivity/brain structure. Overall, the findings of this thesis build knowledge around the impact of early adverse experiences on brain structure and functional connectivity, as well as mental health, during childhood and adolescence. Using whole-brain approaches, longitudinal data, and large samples, we were able to demonstrate that both childhood maltreatment and low SES are associated with widespread alterations in brain structure and function. These findings bring us one step closer to understanding the neurobiological pathways through which adversity ‘gets under the skin’ and impacts children’s mental health and wellbeing, and opens up exciting avenues for future research.
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ItemA prospective longitudinal study of child development following in-utero exposure to antidepressant medication( 2014)Background: The recognition of the importance of treatment for depression in pregnancy to optimise both maternal and child outcomes parallels the increasing use of antidepressants in pregnancy across many countries in the world. However, there is also research to suggest that women are often reluctant to commence treatment or they abruptly cease antidepressant treatment on becoming pregnant due to concerns about long term safety of exposure for their unborn child. This thesis examines child developmental outcomes following in utero exposure to antidepressant medication using two data sets. These two data sets are distinct in methodology allowing a comparison of both methods and results when examining child outcomes following exposure in pregnancy. Methods: The first study is the Victorian Psychotropic Registry (VPR), a purpose designed, prospective, longitudinal study established by the candidate and where children have been followed from in utero to 5 years of age. The second study is the Longitudinal Study of Australian Children (LSAC), a large, normative, population based cohort across early childhood established by the Commonwealth Government of Australia. Both studies had an antidepressant exposed group of children and a control group and both studies had measures of maternal depression in pregnancy, postpartum and into childhood as well as measures of other exposures in pregnancy, such as alcohol and smoking. The VPR collected all data prospectively whereas the pregnancy measures for LSAC were retrospectively collected in the postpartum. The three areas of child development of focus in this thesis are: cognitive development, motor development and child adjustment and emotional development. Where possible, measures were chosen in LSAC, which closely matched those in age and domain to the VPR. Children were assessed at 4-7 years of age across the two studies. Results: This thesis found that in both data sets there was no evidence of an effect on cognitive development from antidepressant exposure in pregnancy. The results for both motor development and emotional development were more complex. For motor development there was a trend to lower scores in the VPR study on a specific neuropsychological measure of motor development: Movement ABC, without reaching a statistically significant difference but small effect sizes. There was no observational or task measures of motor development in LSAC. Both the VPR study and LSAC found a difference on a screening measure, Peds QL Physical Health Score, with exposed children having a lower score. However, when this was adjusted for the covariate of maternal depression this was no longer significant. Child adjustment and emotional development was examined in two areas. The first was internalizing and externalizing scores, within the VPR on the CBCL and within LSAC on SDQ, the second area was parenting and parent-child relational stress measured in VPR with PSI total stress score and within LSAC with the Parenting Efficacy Scale. VPR found there was no statistically significant difference on either measure for exposed children. Whereas, LSAC found both internalizing and externalizing scores and Parenting Efficacy Scale scores did show statistically significant differences, with higher externalizing and internalizing scores and lower Parenting Efficacy scores in exposed children. However, again when adjusted for the covariate of maternal depression these differences became non significant. Conclusions: Using two independent samples to examine antidepressant exposure in pregnancy on child developmental outcomes, no statistically significant difference was found between children exposed and controls on a range of cognitive, motor, child emotional and adjust outcomes at 4-6 years of age. There was also no difference in mothers who took antidepressants in pregnancy on parenting stress and efficacy at 4-6 years postpartum. However, the secondary findings within LSAC study was that maternal depression in the postpartum, as measured by the K6, was associated with poorer cognitive, language, emotional and parenting outcomes This suggests the very important role of maternal depression in examining longitudinal child outcomes. This thesis has contributed both original data to the limited information available on child developmental outcomes following antidepressant exposure across two distinct studies. By using two studies this thesis has also allowed a comparison of findings using different methodologies. This thesis has also been able to contribute data on the effects of maternal depression on child development. These findings support clinical recommendations and practices, which highlight the importance of detection and appropriate treatment of maternal depression in pregnancy.
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ItemLinguistic politeness in middle childhood: its social functions, and relationships to behaviour and development( 1997-07)This research compared Brown and Levinson’s “face saving” account of linguistic politeness with the everyday or social normative account in the context of children’s requesting skills. The research also explored the relationship between children’s politeness skills and their behavioural adjustment. The subjects comprised four groups of ten-and-a-half year old children: a comparison group without behaviour problems, a hostile-aggressive group; an anxious-fearful group; and a comorbid group. All the children were selected from the Australian Temperament Project subject population based on parents’ ratings of the children on the hostile-aggressive and anxious-fearful subscales of the Rutter Child Behaviour Questionnaire. Study 1 found that all the groups of children discriminated between others on the power and distance dimensions in ways consistent with social norms, e.g. adults are judged as more powerful than children. Study 1 also showed that the hostile-aggressive and comorbid groups were significantly less likely to discriminate between others on these dimensions compared to the comparison group. Study 2 showed that for all the children studied politeness as a normative way of speaking was marked by use of please whereas face saving politeness was marked by the use of question directives and hints compared to other request forms. Further, Study 2 showed that there were no differences between children with and without behaviour problems in their use of please to mark different ways of asking.