Melbourne School of Psychological Sciences - Theses
Permanent URI for this collection
Search Results
1 - 3 of 3
-
ItemSleep, mood, and cognitive vulnerability in adolescents: a naturalistic study over restricted and extended sleep opportunities( 2013)Introduction: It is well established that for adolescents, school days are associated with sleep restriction, and that insufficient sleep has been linked to mood disturbances. This longitudinal study assessed sleep, mood, and life stress over the school term and vacation periods with restricted and extended sleep opportunities. The relationships between objective and subjective sleep, as well as between sleep and mood were examined. A cognitive model was proposed and tested to assess whether sleep-specific (i.e., dysfunctional beliefs and attitudes about sleep) and global (i.e., dysfunctional attitudes) cognitive vulnerabilities played a role in these relationships. Methods: One-hundred and forty-six adolescents (47.3% male) aged 16.2+/-1.0 years (M+/-SD) from the general community wore an actigraph continuously for four weeks: the last week of a school term (Time-E), the following two-week vacation (Time-V), and the first week of the next term (Time-S). Social demographic information, chronotype, and cognitive vulnerabilities were assessed at Time-E. Subjective sleep, symptoms of depression, anxiety, and life stress were repeatedly measured at Time-E, Time-V, Time-S, and the middle of the subsequent school term. Regression analyses were used to explore the relationship between sleep and mood, and structural equation modelling was used to examine changes of variables over time, as well as the moderating roles of cognitive vulnerabilities. Results: Compared with school days, sleep during the vacation was characterized by later timing, longer duration, lower quality and greater variability. Daily changes in actigraphy- measured sleep over the vacation period showed linear delays in sleep timing throughout the vacation, while changes in time-in-bed were non-significant. The first vacation week was characterized by a linear decrease in total sleep time and sleep quality, and these changes stabilized during the second vacation week. Compared to vacations, school terms were associated with higher symptoms of depression, anxiety, and life stress. Poorer sleep quality, particularly poorer subjective perception of sleep quality, was significantly associated with higher symptoms of depression and anxiety. Sleep- specific cognitive vulnerability moderated the relationship between objective and subjective sleep onset latency during extended but not restricted sleep opportunity. After controlling for life stress, global cognitive vulnerability played different moderating roles in the relationship between subjective sleep and mood over school term and vacation periods. Higher global cognitive vulnerability was associated with a stronger relationship between subjective sleep and symptoms of anxiety (but not depression) during the school term, as well as with a stronger relationship between subjective sleep and symptoms of depression (but not anxiety) during the vacation period. Conclusion: Sleep, mood, and life stress changed markedly over the school term and vacation periods. Changes in sleep over the vacation suggested that the recovery from school- related sleep restriction was completed within two weeks’ extended sleep opportunity, and the average sleep duration over this period suggested that sleep requirements in adolescence may be less than conventionally described in the media and in the scientific literature. Cognitive vulnerabilities played important roles in the relationship between sleep and mood. Adolescents with higher cognitive vulnerability might be more emotionally vulnerable towards school-related sleep restriction. These findings have important implications for future studies, as well as practical implications for policies and interventions designed to improve adolescents’ wellbeing.
-
ItemNeighbourhood disadvantage and internalising symptoms in adolescents: the mediating role of stressful life events, temperament, and maternal aggression( 2013)Purpose of the study: Disadvantaged neighbourhoods are associated with increased risk for anxiety and depression in adolescents. However the mechanisms for this relationship are not fully understood. Using a longitudinal design, I investigated whether several potential mediators, including stressful life events, maternal aggressive, dysphoric and positive behaviour, and adolescent temperament (Surgency, Negative affectivity, Effortful Control, Affiliation), could help explain the relationship between neighbourhood disadvantage and symptoms of anxiety and depression in early- to mid-adolescence. Method: A community sample of 245 adolescents and their parents participated in a range of assessments at baseline (age approximately 12-13 years old), including an observational assessment of parent-adolescent interactions, and a battery of adolescent-rated questionnaires. Neighbourhood disadvantage was assessed by combining Postal Area data collected during this first wave of assessment with a measure of disadvantage called the Socio-Economic Indexes For Areas (SEIFA) developed by the Australian Bureau of Statistics Adolescents were followed-up approximately 4 years later and completed questionnaires assessing depressive and anxious symptoms. Results: Analyses revealed that adolescents from disadvantaged neighbourhoods were more likely to report a greater number of stressful life events, and depressive and anxious symptoms. They were also more likely to score higher on temperament measures of Negative Affectivity, and lower on measures of Surgency and Effortful control. Mothers from disadvantaged neighbourhoods were more likely to display aggressive and dysphoric behaviour for longer periods, and positive behaviour for shorter periods, however no differences were detected in regard to the frequency of these behaviours. Mediational analyses using a bootsrapping approach determined that stressful life events and three temperament dimensions (low Surgency, low Effortful Control, high Negative Affectivity) significantly mediated the relationship between neighbourhood disadvantage and symptoms of anxiety and depression at baseline. Stressful life events and maternal aggression significantly mediated the relationship between neighbourhood disadvantage and change in depressive and anxious symptoms from baseline to follow-up. Conclusion: The research reported in this thesis provides evidence that disadvantaged neighbourhoods differ from less disadvantaged neighbourhoods in several different ways. In addition, various factors were found to partially mediate the relationship between neighbourhood disadvantage and anxiety and depression at different periods during adolescence. Temperament appears to be important earlier in adolescence, maternal affective behaviour seems to be important during mid- to later-adolescence, while stressful life events appear to act throughout adolescence. These findings suggest that the neighbourhood environment is likely to influence adolescents both directly, and indirectly through its effects on more proximal and individual risk factors. It was concluded that prevention and intervention programs targeting a range of risk factors in adolescents from disadvantaged neigbourhoods could be particularly effective at reducing the prevalence of internalising disorders in adolescents.
-
ItemAffective responsivity in Williams Syndrome: behaviour, psychophysiology, and brain( 2013)The primary goal of this thesis was to evaluate the behavioural and psychophysiological affective response profiles of Williams syndrome (WS) individuals, and to examine the links between these affective responses and amygdala structure and function. It is proposed that abnormalities in the structure and function of the amygdala would be associated with atypical affective responsivity in WS individuals. To achieve these goals, three studies were conducted. Study 1 compared affective behavioural responsivity of WS and control groups across domains of music, anxiety, fear, and sociability. This study also evaluated the relationships between these affective behaviour domains to compare inter-domain relationships between WS and controls. A secondary goal of this study was to evaluate the stability in sociability scores in WS individuals over a five year period. Study 2 compared affective psychophysiological responsivity of WS and control groups in terms of several psychophysiological measures, namely, startle eyeblink, (SEB), zygomatic activity (ZY), corrugator activity (CO), skin conductance (SC), and heart rate (HR). Psychophysiological responsivity, especially affective SEB modulation, was considered an indirect means of evaluating amygdala functioning. Study 3 evaluated relationships between behavioural and psychophysiological affective responsivity and amygdala volume in WS individuals. Data for Study 1 and Study 2 were collected concurrently. In brief, 25 genetically confirmed WS individuals and 25 normal control participants, matched on chronological age, sex, and handedness, ranging in age from 10 to 37 years, were evaluated. Participants were administered measures that assessed handedness, intelligence, affective behavioural responsivity in domains of music and sociability, and psychophysiological responsivity. Parents/guardians completed questionnaires detailing participants’ fears, anxieties, and musical interests. In Study 1, for a subset of 19 of the 25 WS participants, sociability scores were collected at two time points, at Time 1, five years prior by Martens (2005) and Time 2, during the current study, to examine stability of scores over time. In Study 3, for 17 of the 25 WS participants, amygdala volumes, measured via MRI scans at Time 1 were used to predict affective behavioural and psychophysiological responsivity at Time 2. The findings in Study 1 showed higher affective responsivity to music, elevated fear and anxiety, and hyper-sociability in WS participants, compared to controls. The associations between affective responsivity in these behaviour domains differed across the WS and control groups. The findings in Study 1 also showed stability in sociability scores over a five year period between Time 1 and Time 2. The findings in Study 2 demonstrated exaggerated psychophysiological responsivity in the WS group, compared to the control group, in terms of SEB, ZY activity, CO activity and HR, but not SC. The findings of Study 3 indicated that disproportionately large right amygdala structure and atypical right function in particular are markers of abnormality, which appear to underpin an affective response profile characterised by reduced defensiveness and increased heightened attentional processing of affective stimuli. The observed patterns of affective behavioural responsivity provided some preliminary support that the left and right amygdalae modulate affective behavioural responses in a different manner. Taken together, the findings in Study 1 and Study 2 suggest heightened affective responsivity in WS individuals, compared to controls. The findings in Study 3 suggest that disproportionately large right amygdala volume and atypical right amygdala function in particular are associated with some aspects of the affective response profile of WS individuals, although not always in a manner consistent with between group differences. Overall, the findings provide some limited support for the argument made in this thesis that abnormalities in the amygdala would be associated with atypical affective responsivity in WS individuals, but the need for further research on the role of other structures is clear. The findings across the three studies are discussed in relation to an integrated and overarching model, the Hyper-responsive Amygdala Model, which links affective behavioural responsivity, psychophysiological responsivity, amygdala structure, and amygdala function in WS individuals.