Melbourne School of Psychological Sciences - Theses
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ItemSleep and PTSD: bi-directional relationship and underlying mechanism( 2023-04)Post-traumatic stress disorder (PTSD) is a debilitating and enduring disorder that a small but significant number of people develop following exposure to a traumatic event. A common feature of PTSD is disrupted sleep including insomnia and nightmares. Ongoing difficulties in sleeping prevent the sleep-dependent adaptive processing of traumatic memories. Further, sleep disruptions prevent recovery, and perpetuate the disorder when established. This thesis aimed to investigate the bi-directional association between changes in sleep and PTSD symptoms as well as between sleep and underlying fear memory processes. In part I, I examined the immediate effect of changes in sleep on fluctuations of PTSD symptoms and vice versa. Here I used both subjective and, for the first time, objective measures of sleep (study 1). This study found differences in the association between sleep and daytime PTSD symptoms depending on the sleep measurement method. Additionally, preliminary evidence suggests sex-specificity in the association between night-time sleep and daytime PTSD symptoms. Part II focused on the role of sleep in fear conditioning and extinction learning – the experimental model of PTSD development and treatment. Extinction learning and extinction recall (i.e., the ability to learn and remember that previously dangerous stimuli are not threatening anymore) are thought to be impaired in PTSD and impacted by sleep. Particularly rapid eye movement (REM) sleep has been suggested as the sleep stage most important for processing emotional memories. First, a systematic review summarized the available literature assessing the effect of REM and other sleep stages using a meta-analytic approach (study 2). The overwhelming majority of research highlighted the importance of REM sleep, but the meta-analysis did not find the expected REM sleep effect on extinction recall. Following this and the finding from part I, the third and last study investigated the effect of subjectively reported sleep on fear conditioning and extinction learning (study 3). Again, no effect of subjective sleep indices on extinction recall was found. However, both studies found that there were differences between sexes and outcomes were dependent on the diagnostic status (study 2) or rather PTSD severity (study 3). Together, this thesis filled important gaps in the literature and highlighted that sleep is important in the expression of PTSD symptoms in day-to-day life as well as in the mechanism underling PTSD such as fear conditioning and extinction learning. However, the effect of sleep may vary depending on key associated factors. Specifically, the relationship may differ depending on the sleep measurement method (objective and subjective), the samples studied (clinical and control populations) and sex (men and women).
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ItemInfant Exposure to Intimate Partner Violence and Cognitive, Emotional, and Behavioural Development in Middle Childhood: Identifying Protective Factors in Schools( 2022)Children exposed to intimate partner violence (IPV) are at heightened risk of poor developmental outcomes, including impacts on their cognitive, social, emotional, mental, and academic functioning. However, little is known about the long-term outcomes of children exposed to IPV during infancy, and little is known about the protective role of schools for children exposed to IPV. The objective of this thesis was to generate evidence regarding the impact of early-life IPV on children’s cognitive, emotional, and behavioural development, and to examine the role of schools in moderating children’s outcomes. A multi-method approach was used across four studies. The first study was a systematic review of the relationship between IPV and child cognitive development. The second study used data from a longitudinal prospective pregnancy cohort study (N = 615) to explore the association between IPV exposure during infancy and cognitive functioning in middle childhood. The third study built upon the second by using longitudinal data (N = 1507) to explore the moderating role of school experiences in the association between IPV exposure and child cognitive, emotional, and behavioural functioning. Finally, primary school staff (N = 13) were interviewed in the fourth study to explore their perspectives on supporting the development of children exposed to IPV in schools. Results from Study 1 (presented in Chapter 7) indicated that IPV is associated with a range of cognitive outcomes, but there was limited research investigating executive functioning skills such as attention and working memory. In Study 2 (presented in Chapter 8), exposure to IPV during infancy was associated with general cognitive ability and executive attention in middle childhood, while IPV exposure in middle childhood was not associated with any cognitive outcomes. In Study 3 (presented in Chapter 9), exposure to IPV during infancy was associated with general cognitive ability and externalising symptoms in middle childhood, while IPV exposure in middle childhood was associated with both externalising and internalising symptoms. Positive school experiences, including high levels of support and connectedness and low levels of peer victimisation, acted as a moderator buffering against the effects of IPV exposure, such that children with positive school experiences demonstrated lower externalising symptoms. Study 4 (presented in Chapter 10) described a range of important themes for primary school staff supporting children exposed to IPV, including identifying IPV, impacts across development and school functioning, current school supports for students, staff experiences of supporting students, and their suggestions for further training to assist them working with children exposed to IPV. IPV is a serious traumatic childhood experience that can have impacts on long-term cognitive, emotional, and behavioural development, and the school environment is an important protective factor. These findings have implications for health and education policy and practice regarding awareness of IPV and responses to IPV during the perinatal period, interventions and supports for the cognitive and emotional functioning of children exposed to IPV, and increasing the capacity of schools to support children exposed to IPV. Future research directions include incorporating children’s voices, analysis of different patterns and trajectories of IPV exposure and underlying mechanisms in the association between IPV and development, and examination of specific protective factors for child resilience.
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ItemHarm-related concept breadth: Variability in understandings of prejudice, bullying, trauma, and mental disorder( 2021)Concept creep is the gradual semantic broadening of harm-related psychological concepts such as bullying, prejudice, trauma, and mental disorder (Haslam, 2016). If, as concept creep theory suggests, understandings of harm-based psychological concepts are undergoing a process of expansion, a cross-section of individuals might demonstrate different rates of adoption of these shifting meanings. This program of study sought to 1) empirically demonstrate individual differences in ‘harm concept breadth’ (HCB), 2) determine their structure, 3) develop a nomological network for HCB, and 4) test two models of HCB’s psychological basis. Study 1 developed the 40-item Harm Concept Breadth Scale, including refining an item pool, evaluating internal consistency, and preliminarily testing the latent structure of HCB. Study 2 and Study 3 replicated the internal consistency and latent structure of the scale, and established relationships between HCB and measures of sensitivity to self- and other-directed harm, conceptual inclusiveness, gender, and political orientation. Study 4 tested a sociodemographic model in which childhood material security predicts HCB via endorsement of postmaterialist values. Both variables predicted greater HCB, suggesting that satisfaction of material needs and values prioritising wellbeing and egalitarianism are independently related to holding broader concepts of harm. Study 5 investigated a mechanism by which childhood material security might influence HCB. The differentiated threat sensitivity model proposes two higher order threat dimensions: sensitivity to material and non-material threats (e.g., injury and disease versus exclusion and negative evaluation). In the model, threat perception is sensitised to relevant stimuli during childhood, and this differentiated sensitivity influences HCB. Material and non-material threat sensitivity dimensions were empirically distinguished. Non-material threat sensitivity was found to uniquely predict HCB, but did not mediate the relationship between childhood material security and HCB. Study 6 and Study 7 experimentally tested the causal effect of non-material threat sensitivity on HCB. In Study 6 an exclusion threat manipulation (Cyberball; Williams & Jarvis, 2006) had no effect on HCB. In Study 7 a novel experimental paradigm tested the effect of evaluative threat on HCB. Consistent with the differentiated sensitivity model, evaluative threat had an indirect effect on HCB via fear of negative evaluation. This research program makes several theoretical and practical contributions to the field. HCB is a novel construct with implications for a range of significant social phenomena. Disparities in breadth of harm-based concepts may play a role in ideological polarisation and conflict regarding the moralisation of social behaviours. Greater understanding of factors that increase sensitivity to concepts such as trauma and mental disorder may prove valuable in identifying vulnerabilities to psychological harm. This research develops the first reliable and valid measure of HCB. A further theoretical innovation is the identification of higher order dimensions of threat sensitivity, providing fertile ground for revisiting literature linking unidimensional threat to social psychological phenomena. In sum, this thesis provides the first exploration of a novel construct with theoretical and practical implications for our understanding of political polarisation, moral disagreement and vulnerability to psychological harm
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ItemAn investigation of parent posttraumatic cognitions and mental health outcomes after trauma exposure in children( 2017)Introduction: Parent posttraumatic cognitions have received little attention in the childhood posttraumatic stress literature, yet potentially play an important role in understanding how parents influence children’s recovery after trauma. The manner in which parents respond to their child’s experience is important in the development and treatment of childhood posttraumatic stress disorder (PTSD), and a range of parenting behaviours and parent psychological problems have been linked to childhood posttraumatic stress (Trickey, Siddaway, Meiser-Stedman, Serpell, & Field, 2012; Williamson et al., 2017). To date, limited empirical attention has been given to the nature of cognitions in parents of trauma-exposed children, and the research has been restricted to the use of small item pools, as a multidimensional measure of parent posttraumatic cognitions related to the child’s recovery had yet to be operationalised. The overall aim of this program of research was to develop a measure of parent posttraumatic cognitions for use after a child has experienced a traumatic event, and to examine whether these parent cognitions related to child and parent mental health outcomes. Method: This research had two parts. In Part A, a parent-report questionnaire, the Thinking About Recovery Scale (TARS), was developed to assess specific negative posttraumatic cognitions parents may have after their child is exposed to trauma. The theoretical-rational approach to scale development was used to generate items, which were then subjected to review by experts in the field of childhood trauma. In Part B, the TARS was used in a cross-sectional study, the Thinking About Recovery Project, to examine whether parent posttraumatic cognitions were related to mental health outcomes using a sample of parents and children after children’s experience of accidental injury. Participants were 116 parents and 88 children aged 8-16 years who had been physically injured (e.g., sporting injury, burns, motor vehicle accident) and subsequently admitted to hospital for at least 24 hours. Data collection involved questionnaires to assess parent and child posttraumatic cognitions and mental health outcomes (posttraumatic stress, depression, anxiety, externalising symptoms) between 3 and 6 months post injury. Results: The development and psychometric evaluation of the TARS is reported. The 33-item scale measuring three domains (My child has been permanently damaged; The world is dangerous for my child; Parents should always promote avoidance) demonstrated sound internal consistency and convergent validity when piloted in a sample of 116 parents of children who had been exposed to a serious accidental injury. Posttraumatic cognitions parents had about themselves, the world, and their child’s recovery were significantly associated with both parent and child posttraumatic stress symptoms (PTSS), and a range of other mental health outcomes. A range of parent posttraumatic cognitions were significantly associated with child posttraumatic cognitions. Parent cognitions related to the child mediated the relationship between parents and child PTSS. Discussion and Conclusion: This research was a necessary step in advancing knowledge about parental influences on children’s recovery from traumatic events. Findings provide an empirical basis for ongoing investigation into how parent posttraumatic cognitions may be contributing to the development and maintenance of PTSD symptomatology in parents and children, with particular consideration to cognitions parents have related to their child’s recovery.
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ItemThe role of candidate gene x environment interactions in eating pathology: an investigation of the 5-HTTLPR polymorphism( 2017)The present thesis with publication aimed to clarify current scientific understanding of candidate gene x environment (GxE) interactions in the eating disorder (ED) field, and to build upon existing findings through specific investigation of adolescent disordered eating and the 5-HTTLPR polymorphism. Study 1 involved a systematic review of published studies of GxE interactions involving 5-HTTLPR in the ED field, followed by four meta-analyses involving the combination of raw data from the original studies. From the four analyses undertaken (investigating the environmental variables traumatic life events, N = 909, sexual and/or physical abuse, N = 1,097, and the psychological variables depression, N = 1,254, and impulsivity, N = 1,122), results supported moderation by 5-HTTLPR in the relationship between sexual and physical abuse and bulimic spectrum pathology, with some support for moderation by 5-HTTLPR in the relationship between traumatic life events and overall EDs. No interactions between 5-HTTLPR and psychological factors were identified. Study 2 aimed to conceptually replicate these results in a large, independent sample drawn from the Australian Temperament Project (N = 650). Results showed no interaction between 5-HTTLPR and psychological factors (depressed mood or emotional control), but revealed a severity-dependent effect whereby there was some evidence of moderation by 5-HTTLPR in the relationship between severe, but not moderate-to-mild, parental physical punishment and adolescent EDI-2 Bulimia scores. The final investigation, Study 3, examined potential direct effects and GxE interactions between parenting and 5-HTTLPR to predict disordered eating from a ‘plasticity’ perspective, across two samples. Study 3a found an association between self-reported parental warmth and lowered EDI-2 Bulimia scores, and between self-reported parental use of physical punishment and greater EDI-2 Drive for Thinness scores (N = 650), however no moderation by 5-HTTLPR was identified. Study 3b aimed to replicate these findings using an observational measure of parenting behaviours, and constituted the largest study of observed parenting behaviours in the ED field (N = 304), as well as the first GxE interaction study in the field to include observational measurement of parenting behaviours. Results showed an association between parental warmth and lower EDI-2 Drive for Thinness scores, but no association between parental hostility and disordered eating, or any GxE interactions. Overall, results across the three studies of the present thesis supported moderation by 5-HTTLPR in the relationship between severe environmental stressors and eating pathology, but not between less severe environmental factors or psychological factors and ED outcomes. These results illustrate the important role of genetic factors in ED aetiology, carry implications for understanding the individual differences in response to potential environmental risk factors for EDs, and can be used to help inform ED prevention initiatives. Outstanding issues in investigation of candidate gene research in the ED field include sample size, publication bias, and multiple testing. Continued collaboration to increase sample sizes and careful selection of environmental and psychological measures is recommend for future GxE investigations, along with a move towards polygenic and genome wide investigative approaches.
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ItemTrauma and psychosis: investigating the role of post-traumatic intrusions, schemas and avoidance( 2016)Increasing evidence suggests that childhood trauma may play a role in the aetiology of psychosis, leading to suggestions that trauma-related symptoms may be mechanisms in the process. Two prominent cognitive models implicate post-traumatic intrusions and trauma-related schemas and emotion as key mechanisms. Neither of the models has been extensively tested, and both have implications for the content of hallucinations and delusions in relation to traumatic experiences. The aims of the current study are to 1) investigate statistical associations between the severity of trauma and psychosis, 2) investigate phenomenological associations between trauma, post-traumatic intrusions, hallucinations and delusions, and 3) explore the relationship between trauma-related avoidance and psychosis. Sixty-six people with first episode psychosis aged between 15 and 24 years were assessed for childhood trauma, post-traumatic stress disorder (PTSD) symptoms, psychotic symptoms and experiential avoidance. The content of hallucinations, delusions, post-traumatic intrusions and traumatic experiences (up to five of each) was assessed. Content relationships between hallucinations, trauma and post-traumatic intrusions were categorised as ‘direct’ (where hallucination content was identical to trauma or intrusion content), ‘indirect’ (where hallucinations contained elements of trauma/intrusion-specific content but were not exact representations of traumas/intrusions) or ‘thematic’ (where hallucinations were related to trauma or intrusions at the level of broader, schema-related themes). Sixty-five percent of the sample had experienced childhood trauma, and 26% met diagnostic criteria for PTSD. Childhood trauma severity was correlated with hallucination and delusion severity with moderate effect sizes (although the correlation with hallucinations did not reach significance). Post-traumatic intrusions correlated with both hallucinations and delusions with moderate to large effect sizes. In terms of hallucination content, 78% of people with hallucinations and childhood trauma had hallucinations related in content to their trauma. These relationships were primarily thematic, although a notable minority (25%) had hallucination content directly representative of their trauma. Sixty-four percent of people had more than one type of relationship (direct, indirect, thematic, or no relationship) between their trauma and hallucination content. Of those with hallucinations and post-traumatic intrusions, 73% experienced hallucinations related in content to their post-traumatic intrusions. For delusion content, 89% of people with delusions and trauma had delusional content related to their trauma. Relationships between childhood trauma, avoidance, hallucinations and delusions were investigated, and it was found that childhood trauma was correlated with experiential avoidance (with a moderate effect size), and that both experiential avoidance and post-traumatic avoidance were correlated with hallucinations and delusions (with moderate effect sizes). In a series of multiple linear regressions, post-traumatic intrusions (but not childhood trauma, post-traumatic avoidance, experiential avoidance or maladaptive schemas) were independently associated with hallucination severity and explained 13% of the variance in hallucinations. Post-traumatic intrusions and maladaptive schemas (but not childhood trauma, post-traumatic avoidance or experiential avoidance) were independently associated with delusion severity, and explained 14% and 5-8% of the variance in delusion severity respectively. These findings suggest that post-traumatic intrusions and maladaptive schemas may be particularly important mechanisms in the relationship between trauma and psychosis, and may be playing a stronger role than avoidance. This has implications for the treatment of trauma and PTSD symptoms in people with psychosis. Research trialling interventions that specifically target post-traumatic intrusions and schemas in people with early psychosis who have experienced childhood trauma is recommended.
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ItemResilience and recovery from trauma among Aboriginal help seeking clients in an urban Aboriginal community controlled organisation( 2016)This thesis explores aspects of historical loss, contemporary trauma, and resilience and recovery outcomes among Aboriginal help-seeking clients from the Family Counseling Services of the Victorian Aboriginal Health Service in Melbourne, Australia. In the first study, Aboriginal health professionals participated in focus groups and a 60-item Aboriginal Resilience and Recovery Questionnaire was developed. The results of a principal components analysis suggested the retention of two components that represent personal strengths and relational-cultural strengths. These two sub-scales and their composite scores (referred to as global strengths) were used in the subsequent study. In the second study, 81 Aboriginal clients from the Family Counseling Services participated in structured interviews that included self-report measures of historical loss, trauma exposure, stressful life events, posttraumatic stress symptoms, depression, drug and alcohol use, empowerment, resilience as coping with stress, and personal, relational-cultural and global strengths. Levels of trauma exposure were high among participants, and commonly endorsed symptoms of distress included those consistent with Posttraumatic Stress Disorder (PTSD), Complex PTSD and cultural idioms of distress as documented in the Aboriginal Australian Version of the Harvard Trauma Questionnaire (AAVHTQ). Forty per cent of the participants in the study were classified as PTSD symptomatic according to the AAVHTQ. Descriptive statistics showed that Aboriginal clients participating in the second study reported poorer outcomes across a range of social determinants and adversities in comparison to other Aboriginal Victorians in the general population. Two generations of child removal from one’s natural family, historical loss, experiences of racism, and not having access to funds for basic living expenses were all associated with greater trauma symptoms severity. Conversely, personal and relational-cultural strengths, and global strengths, were associated with lower trauma and depression symptom severity, and drug and alcohol use. Participants who reported experiencing more healing from past trauma also reported higher scores on subscales related to managing intense emotions, experiencing positive emotions, strong relationships (attachment), feeling safe, resilience as coping with stress, personal and relational-cultural strengths, and global strengths. Regression analyses revealed that trauma exposure, stressful life events,resilience as coping with stress, personal and relational-cultural strengths, and global strengths, were all important predictors of posttraumatic stress symptom severity. Stressful life events were found to partially mediate the relationship between trauma exposure and trauma symptom severity. When entered together as independent variables, only personal strengths had a main effect on trauma symptom severity, whereas relation-cultural strengths had a moderating effect on the relationship between trauma exposure and trauma symptom severity. Also, global strengths were found to moderate the relationship between trauma exposure and trauma symptom severity. When examining community and cultural-based subscales as predictors, only community opportunity and communal mastery were found to predict trauma symptom severity. Finally, post-hoc analyses revealed that global strengths also moderated the relationship between historical loss and trauma symptom severity, while cultural practices were found to be a predictor of empowerment, with self-esteem partially mediating the relationship between cultural practices and empowerment. Taken together, findings from the second study indicate a range of important risk and protective factors that help to differentiate post trauma outcomes among Aboriginal help-seeking clients attending the Family Counseling Services. Some of these factors are consistent with the PTSD and Complex PTSD recovery literature. Others represent unique socio-historical and cultural-resilience based factors that are particularly salient for Aboriginal Victorians. The Aboriginal Resilience and Recovery Questionnaire shows promise as a measure that can be used by Aboriginal counseling services across Australia to better assess the extent to which its therapeutic practices and programs support Aboriginal help-seeking clients in increasing their strengths and resources, and experiencing healing and trauma recovery outcomes.