Melbourne School of Psychological Sciences - Theses
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ItemThe genetic basis of singing ability: a twin study( 2016)Music is a human universal, an integral part of all known human culture. While most people possess the capacity for music perception and production, individual differences in various forms of music abilities are evident in the general population. The diversity in abilities has sparked intense debates regarding the relative importance of nature and nurture in shaping music ability. While in recent years, researchers have begun to explore the genetic basis of music perception abilities, the interrogation of the genetic basis of music production abilities has been relatively scarce. Singing is an ideal paradigm for investigating the genetic basis of music ability; it is a universal, multifaceted music ability that is spontaneously emergent and shaped by formal and informal music learning environments. The present study therefore employed a twin study design to investigate the genetic basis of singing ability and estimate the relative contribution of genetic and environmental factors influencing singing ability using a comprehensive set of singing tasks and measures. The study also aimed to identify environmental factors associated with singing ability and examine whether these factors have a genetic component, and whether shared genetic influences might explain the association between singing ability and these factors. The twin study was conducted online using a purpose-built online program Let’s Hear Twins Sing, which enabled twins to participate regardless of their geographical location. The 30 minutes online twin study comprised three singing tasks (vocal pitch-matching, singing a familiar song, and melody imitation), two music perception tasks and a questionnaire on music and singing background. The study took approximately 30 minutes to complete and the study data were captured online in real-time and saved on a server for subsequent analyses. The final sample consisted of 70 monozygotic (55 female; 15 male) and 38 dizygotic (24 female; 7 male; 7 male-female) twin pairs (mean age = 32.4 years), the majority were recruited through the Australian Twin Registry. Univariate genetic modelling revealed that both the objectively-assessed singing ability across all tasks and self-rated singing ability had similarly significant and substantial genetic components (A = 69-72%). Additive genetic influences also contributed significantly to the variation observed in various singing task measures, with moderate to large heritabilities (A = 44-71%), negligible to moderate common environmental (C = 0-37%) and moderate unique environmental (E = 19-40%) influences. Significant moderate to large genetic components were also estimated for environmental variables associated with singing ability: instrumental expertise (A = 68%), years of music training (A = 46%), and public singing engagement (A = 66%). Bivariate genetic analyses revealed that the associations between singing ability and both instrumental expertise and years of music training were mediated significantly by shared additive genetic influences. The novel findings therefore provided preliminary evidence for the role of genes in influencing singing ability and formal music training, as well as a partially shared genetic basis for singing ability and music training. The promising results establish a valuable background that encourages further behavioural and molecular genetic interrogations into the genetic bases of various types of music abilities.
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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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ItemFatigue after child brain injury( 2016)Objective: Traumatic brain injury (TBI) is one of the most frequent causes of childhood disability. Fatigue is commonly reported during the acute and chronic phases of TBI recovery. Fatigue is defined as reduced performance in response to prolonged or unusual exertion and leads to reduced quality of life and school participation in children. Despite the prevalence of fatigue following TBI, there is little examining its nature and course. In particular, patterns of fatigue over time and predictors of longitudinal outcome after child TBI are unclear. The aim of this thesis is to address identified gaps in the existing research within the field of fatigue after child TBI. Throughout, we adopt a model of fatigue that is developmentally sensitive and multidimensional – including physical, sleep/rest, and cognitive elements. First, through systematic review of the literature we identify a psychometrically robust fatigue assessment instrument for use in child TBI. We then use this multidimensional fatigue measure to assess fatigue at three time-points after child TBI: 6 weeks, 6- and 12-months in order to meet the following study aims. First, we aim to compare fatigue in our TBI sample to published control data (at 6-weeks and 12-months post-injury), by TBI severity. Second, we examine fatigue over time (6- to 12-months post-injury) within our sample. Fourth, we explore factors predictive of worse fatigue on the fatigue measure at 6-weeks (child and parent perspectives) and 12-months (parent perspectives) post-injury. Our hypotheses were that fatigue following child TBI (a) would be higher than reported in published healthy children control data, (b) would reduce over time post-injury and (c) would be associated with more severe TBI and other hypothesised risk factors (such as sociodemographic characteristics). Method: Phase 1: A systematic review of fatigue assessment instruments used in children was conducted using key academic databases. Study quality and the psychometric properties of the instruments were assessed. Phase 2: We included participants already recruited to a larger prospective longitudinal study comprising 159 children (0-17 years at injury) with mild, moderate or severe TBI, presenting to one of three participating sites (two Canadian, one Australia). From the larger cohort, a subsample of 47 adolescents (8-18 years at injury) also participated in follow-up- 6-weeks post-injury. As part of the larger study protocol, at the time of child TBI, parents provided pre-injury child data based on retrospective report, including report of pre-injury fatigue and sleep difficulties. Healthy control data published from an American sample of children age 2-19 years was used for group comparisons (Panepinto et al., 2014). Results: Phase 1: Systematic Review identified twenty fatigue instruments, and two demonstrated strong measurement properties. Phase 2: Fatigue was rated by 35 participants (parents and adolescents) 6-weeks post-injury. At 6-weeks post-injury, fatigue in child TBI was significantly worse relative to control data (47 per cent and 29 per cent rated severe fatigue respectively). Between 6- and 12-months post-injury there was no detectable improvement in fatigue. Rather, cognitive fatigue worsened over time. Fatigue 12-months post-injury was again worse relative to control data (parent ratings). Fatigue was predicted by multiple variables, including pre-injury sociodemographic factors (female sex), psychological well-being (general fatigue) and pre-injury fatigue (sleep/rest fatigue). Symptoms after injury in multiple domains (physical/motor, pain, sleep psychological or inattention) additionally predicted fatigue 12 months post-injury. Conclusions: Fatigue is a complex, severe and persistent complaint after child TBI. Interventions are required to help reduce fatigue after child TBI.
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ItemCognitive load effects on early visual processing( 2016)The dominant view maintained in the dual-task literature suggests that multitasking usually results in performance impairment due to cognitive resource limitation. But a limited number of dual-task studies have found that cognitive loads did not affect early perceptual processing of a second task. These findings were interpreted as suggesting that early perceptual processing does not require the support of cognitive resources (Chun et al., 2011; Lavie, 2005; Pashler, 1994). Surprisingly, a recent study showed that while participants were maintaining some visual working memory, performance on an unrelated visual perceptual task (i.e., grouping-by-proximity) was improved (Cocchi et al., 2011). The authors interpreted the results as suggesting that the more the cognitive resources are saturated, the more selective the early visual perceptual processing becomes. Such findings and interpretations are in conflict with the those dual-task studies that directly found no effects of cognitive load on early vision. Higher cognitive and perceptual processes are dynamically interrelated and subserved by overlapping brain networks. The seemingly conflicting findings between the study of Cocchi et al. (2011) and load studies highlights the need to systematically evaluate the possible effects of cognitive load on early visual perceptual processing. An increased scientific understanding of the possible cognitive load effects on early perceptual processing bears both theoretical and practical importance. Most early visual perceptual processing is contrast based. The vision researchers adopt a reverse engineering approach towards vision and the application of rigorous psychophysical techniques to studying basic early visual processing of contrast is the common practice. The accumulating research on early vision with such an approach suggests that the early visual perceptual systems are organized in a centre-surround antagonistic fashion and perform a divisive neural computation that determines neural responses in relation to contrast energy – normalization (Heeger, 1992). More importantly spatial attention has been shown to critically modulate the interaction between the centre excitation and surround inhibition such that the size of the spatial attention window determines the amount of surround inhibition that goes into the normalization process to decide the final output of the system (Reynolds and Heeger, 2009). An in-depth review of multiple relevant streams of literature suggests that early centre-surround interactions and the spatial attention effects on these centre surround interactions are the keys to further evaluating the cognitive load effects on early visual perceptual processing. In the current thesis, consequently, a set of four psychophysical experiments served the overall aim of exploring the possible mechanisms by which cognitive load may modulate early visual perceptual processing. Four relatively well-understood visual perceptual tasks that are thought to reflect the centre-surround interaction in early visual processing and spatial attention effects on centre-surround interaction in early vision were adopted. In all experiments, the perceptual tasks were performed during a concurrent no-, low and high-working memory load task. In Experiment 1, a contrast detection task was employed to explore whether cognitive load modulates centre excitation. Participants judged the orientation of a small Gabor of various contrasts located in the periphery. Results of Experiment 1 show that under high cognitive load, centre excitation was diminished suggesting when cognitive resources are depleted, early visual perceptual processing integrity is slightly reduced. In Experiment 2, cognitive load effects on surround inhibition magnitude were assessed using a motion direction discrimination task (Tadin et al., 2003). No effects of cognitive load on surround inhibition were found in Experiment 2. In Experiment 3 and 4, possible cognitive load effects on defocusing spatial attention were assessed in the periphery and fovea separately using a contrast detection task (Petrov and McKee, 2006) and the Chubb illusion task (Chubb et al., 1989) respectively. No effects of cognitive load were found in Experiment 3 and 4. According to the normalization model, the balance between centre excitation and surround inhibition determines contrast response. The results of this study suggest that under high cognitive load the centre excitation is diminished. Possible reasons for the lack of cognitive load effects on surround inhibition and spatial attention distribution are explored. Taken together, these findings show that cognitive load effects can penetrate to the early visual perceptual processing stage, however, with the experimental designs in the current thesis, these effects appear to be limited to centre excitatory mechanisms. Nevertheless, the results of this study suggest that cognitive load slightly reduces top-down modulation from higher cognitive functions to early visual perceptual processing. The findings of the current study are consistent with the findings that cognitive load defocuses spatial attention, which also suggests reduced top-down modulation under high cognitive load.
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ItemSeeing other people: what sensory perception teaches us about social perception( 2016)Stereotyping is a widespread phenomenon with occasionally destructive consequences. It is sometimes framed as a special case of categorisation (Allport, 1954), but since categorisation underlies all perception and decision-making (Ashby & Lee, 1993), this is suggestive of an analogy between social perception and basic, sensory perception. The aim of this thesis is to explore how far this analogy can be usefully extended. Each of the experiments presented uses computer-generated human faces as stimuli, generally requiring participants to make personality inferences about them. This is based on prior research that shows the personality judgments people make can be well described with two dimensions, warmth and competence (Cuddy, Fiske, & Glick, 2008), which are readily perceived in images of human faces (Oosterhof & Todorov, 2008). The empirical content of this thesis is presented in three thematically distinct chapters, followed by a general, concluding section. Multidimensional Scaling with Personality Perception Multidimensional scaling can use participants’ similarity judgments to model psychological space (Borg & Groenen, 2005). Since similarity is the yardstick of psychological space (Shephard, 1987) and stereotype-relevant constructs such as perceived homogeneity and atypicality can be expressed in terms of similarity, this makes MDS seem like a potentially promising way to characterise social perception. The three experiments in this chapter demonstrated that multidimensional scaling fits of judgments of the similarity of the inferred personalities of human faces reproduce several phenomena in the realm of social perception and also made novel findings. This method is thus validated for the study of social perception . Social Knowledge Partitioning in Function Learning According to Sewell and Lewandowsky (2011), ‘When knowledge partitioning occurs, people simplify a complex task by decomposing it into separate local solutions’ (p. 86). Knowledge partitioning demonstrates that purely exemplar-based models are insufficient for describing human cognition. The five experiments presented in this chapter showed that people sometimes partition socially meaningful knowledge, learning distinct rules for African and Caucasian faces when ethnicity does not predict correct responses. Attitude questionnaire scores revealed differences between those who partitioned and those who did not, albeit in an unexpected direction. Attempting to Replicate Ishii and Kitayama (2011) In this chapter, an attempt is made (unsuccessfully) to replicate Ishii and Kitayama’s (2001) ‘perceptual out-group homogeneity effect’ study. Whereas the previous two chapters of this thesis provided positive examples of how far the analogy between social and sensory perception can be usefully extended, this chapter provided a negative example. It is argued that while Ishii and Kitayama’s (2011) reasoning was appealing, the experiment presented in this chapter, which was designed to give the ‘perceptual out-group homogeneity effect’ the greatest possible chance to emerge, failed because their result was a false positive.
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ItemIdentifying dimensions of interest to support learning in disengaged students: the MINE project( 2016)For some time, there has been a concern that many students are disengaged with learning in schools. Despite the well-documented connection between interest in curriculum and learning, discovering what disengaged students are interested in has proven problematic using current methods of interest measurement. This thesis addresses these difficulties by introducing a new method of determining what students are interested in without the need for them to be confronted by direct enquiry. The My Interest Now for Engagement (MINE) software is an easy-to-use, playful and engaging online environment that allows students to explore and report upon interests by expressing their personal preferences. Based on iFish software (Pearce, 2008), The MINE tool also measures how adolescent learners feel about their selected interests through behavioural indicators of dynamic interest experience. Three development studies describe the design and testing of the MINE tool. The first study establishes a collection of appropriate interests for exploration within MINE’s interface. The second study establishes parameters for exploration within the software. The third study tests whether the MINE tool measures the interests of adolescent learners consistently and in line with the established framework. Findings indicated that the MINE tool was an effective measure for profiling adolescents’ interest. MINE was then used to profile the interests of 213 students studying in two academically underperforming schools in Melbourne, Australia. After establishing patterns of what these adolescent learners were interested in, findings indicated gender differences in the patterns of interest content. It was found that high ratings for positive affect, moderate to high ratings for hopeful, and very low ratings for negative affect were associated with expressed interests. The knowledge and value dimensions associated with reported interests were also examined. Behavioural indicators of knowledge and value were used to identify common patterns of interest experience. A four-cluster solution was found using an exploratory two-step cluster analysis. Four common patterns were identified and these were compared with the phases of interest development described in the Four-Phase Model of Interest Development (Hidi & Renninger, 2006). Clusters of interests defined by either low levels of knowledge or value aligned with the situational phases of interest development. Two clusters of interests associated with high ratings for knowledge, and high value, differentiated by very high or very low ratings of perceived effort, were aligned with the individual phases of interest development. The potential usefulness of the main study’s findings to a teacher wishing to engage a student is presented using a representative selection of six case studies. These case studies discuss potential curriculum connections between content and education as well as an in-depth analysis of the interest experience of the individuals being profiled, including interest triggered by the MINE tool itself. This research argues that knowledge of both the content and dynamic processes that combine when interest is activated might be useful for teachers when personalizing learning activities to engage or re-engage a student. The MINE tool generates interest profiles that provide information to teachers seeking to engage adolescent learners who have become disengaged with learning in schools. Hidi, S., & Renninger, K. A. (2006). The Four-Phase Model of Interest Development. Educational Psychologist, 41(2), 111-127. Pearce, J. M. (2008). A System to Encourage Playful Exploriation in a Reflective Environment. Paper presented at the EdMedia conference. Vienna.
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ItemSelf-compassion, self-criticism, parent-child attachment moderate the relation between anxious solitude and psychosocial adjustment in early adolescence( 2016)Research suggests heterogeneity in anxious solitary (AS) children’s internalizing trajectories. The thesis attempts to extend our understanding about the cognitive and relational factors in AS children’s adjustment trajectories. Study 1 explores how self-processes could lead to heterogeneity in AS children’s internalizing trajectories and Study 2 explores the contribution of parental attachment security in the self-compassion and self-criticism trajectories from 5th through 7th grade. Results suggested the importance of targeting self-processes and parental attachment security while designing interventions for AS children’s internalizing difficulties.
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ItemThe longitudinal transmission of effects between eating pathology, depression, and anxiety( 2016)Objective: Eating pathology [e.g., an eating disorder diagnosis or a disordered eating symptom(s)] is highly comorbid with negative mood (i.e., depression, anxiety and negative affect). To date, the transmission of effects between these respective constructs during adolescence remains unclear. Four possible alternatives have been proposed in the literature to account for the longitudinal relationship between eating pathology and negative mood; i) that eating pathology causes negative mood ii) that negative mood causes eating pathology, iii) that the constructs are bi-directionally related, and iv) that each construct is linked via shared risk factors. This thesis aimed to investigate which of the aforementioned models best accounts for the transmission of effects between symptoms of eating pathology with negative mood. In addition to negative mood, research has also identified that body mass index (BMI), pressures to be thin, thin ideal internalization, body dissatisfaction, dietary restraint, and a facet of the personality trait impulsivity, known as negative urgency, confer risk to the development and maintenance of eating pathology (e.g., Stice, 2002; Fischer et al., 2008). Many of these factors have been incorporated into an etiological model of bulimic pathology known as the dual pathway model (DPM), however, to date only one study (Stice, Shaw et al., 1998) has assessed the complete DPM longitudinally, hence, the predictive utility of the model is uncertain. This thesis therefore also aimed to test a revised version of the DPM to include a longitudinal aspect that examined evidence for potential bi-directional effects between symptoms of bulimic symptoms with depression. The revised assessment of the DPM also examined the influence of negative urgency on the model. Method: This thesis contains 3 studies. Study 1 was a systematic review and meta-analysis comprising 42 studies that assessed the longitudinal relationship between eating pathology and depression. Of these 42 studies, multilevel random-effects meta-analyses were conducted on 30 eligible studies. Study 2A assessed the longitudinal effects between different symptoms of eating pathology (e.g., dietary restraint, concerns about eating, shape and weight) with depression and anxiety. Data was analysed from 189 male and females participating in the Adolescent Development Study (ADS), a longitudinal study conducted in Melbourne, Australia. Eating pathology symptoms and depressive and anxiety symptoms were assessed at approximately ages 15, 16.5 and 18.5. Study 2B assessed the same sample as study 2A, but looked at the longitudinal effects between symptoms of eating pathology (e.g., dietary restraint, concerns about eating, shape and weight) with negative affect. Finally, study 3 tested the DPM of bulimic pathology by assessing 245 females (M = 23.77) at baseline (T1) and at one-month follow up (T2). Results: Results from study 1 indicated that depression and eating pathology were bi-directionally related, and that meta-regression revealed that specific study level effect modifiers influenced these effects (e.g., eating pathology symptom type). Results from study 2A indicated that overall disordered eating symptoms, and concerns about shape, weight, and eating were risk factors for anxiety. It was also shown that depression and eating pathology were risk factors for each other, with shape concerns at T1 longitudinally predicting depression at T2, and depression at T2 longitudinally predicting eating concerns at T3. Further, it was shown that the transmission of these effects varied according to participant age (e.g., the effect of depression on eating pathology occurred at a younger age relative to the effect of eating pathology on depression). Results from study 2B showed no support for the longitudinal effects between negative affect and eating pathology. Finally, results from study 3 indicated that the revised assessment of the DPM of bulimic pathology that included negative urgency, demonstrated strong support for the development of symptoms of eating pathology and depression cross-sectionally. Results also provided support for the maintenance of symptoms of depression, bulimia, and dietary restraint longitudinally. Conclusion: Eating pathology and depression are concurrent risk factors for each other. Further, eating pathology appears to confer risk to developing anxiety during adolescence. Findings illustrate the clinical importance of disambiguating the respective facets of eating pathology symptoms to understand the relative risk that each facet confers to depression and anxiety, and vice versa. Results also highlight that preventative interventions during adolescence designed to target specific facets of eating pathology, specifically concerns about eating, shape, and weight, might be most efficacious in reducing the influence of eating pathology symptoms on depression and/or anxiety, and vice versa. Finally, results indicated that shared risk factors (e.g., negative urgency), might be instrumental in reducing symptoms of eating pathology and negative mood.
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ItemThe SENSE study (Sleep and Education: learning New Skills Early): postintervention effects of a randomised controlled trial of a cognitive-behavioural and mindfulness-based group sleep improvement intervention among at-risk adolescents( 2016)Objective: There is growing recognition that many adolescents obtain insufficient and/or poor quality sleep. Sleep problems are also a major risk factor for the emergence of mental health problems in adolescence. However, few studies have examined disturbed sleep as a potential mechanism in the treatment and prevention of mental health problems among adolescents. Adolescent sleep problems can be treated using a range of approaches. School-based sleep education programs, which are typically delivered to whole school classes, have been shown to have little impact on sleep behaviour or mental health. Cognitive-behavioural and mindfulness-based sleep programs, which are typically delivered to at-risk or already symptomatic adolescents, have been shown to be more effective in improving sleep and emotional distress, but studies evaluating their effectiveness have been limited in several ways, including small sample sizes and inadequate/lack of control groups. We conducted a systematic review and meta-analysis examining the efficacy of cognitive-behavioural sleep interventions among adolescents. Searches of PubMed, PsycINFO, CENTRAL, EMBASE, and MEDLINE were performed from inception to 1 May 2016. Eight trials were selected (n=234, mean age=15.24 years; female=63.18%). Main outcomes were subjective (sleep diary/questionnaire) and objective (actigraphy) total sleep time (TST), sleep onset latency (SOL), sleep efficiency (SE), and wake after sleep onset (WASO). There was a small number of randomised controlled trials (RCTs; n=3), and a high risk of bias across the RCTs; therefore within sleep condition meta-analyses were examined. At post-intervention, subjective TST improved by 29.47 minutes (95% CI = 17.18, 41.75), SOL by 21.44 minutes (95% CI = -30.78, -12.11), SE by 5.34% (95% CI = 2.64, 8.04), and WASO by a medium effect size (d = 0.59 [95% CI = 0.36, 0.82). Objective SOL improved by 16.15 minutes (95% CI = -26.13, -6.17), and SE by 2.82% (95% CI = 0.58, 5.07). Global sleep quality, daytime sleepiness, depression, and anxiety also improved. Gains were generally maintained over time. Our meta-analysis provides preliminary evidence that cognitive-behavioural sleep interventions are an effective treatment for adolescent sleep problems, producing clinically meaningful responses within active treatment conditions. Their efficacy is maintained over time, and results in significant alleviation of sleep problems and improvement in functional outcomes. However, further large-scale, high-quality RCTs are needed to confirm these findings. The aim of this thesis was to investigate the post-intervention effects of a cognitive-behavioural/mindfulness-based group sleep intervention on sleep, mental health, and cognitive style among at-risk adolescents. The study went beyond simply measuring treatment outcomes to also evaluate mechanisms of change. Based on the behavioural, cognitive, hyperarousal, and transdiagnostic models of insomnia, a number of specific mediators were hypothesised to account for therapeutic change in cognitive-behavioural and mindfulness-based sleep interventions for adolescents, including earlier bedtimes, more consistent bedtimes, increased sleep hygiene awareness, and decreased dysfunctional beliefs and attitudes about sleep, worry, rumination, pre-sleep arousal, anxiety, and depression. Method: A RCT was conducted across Victorian secondary schools in Melbourne, Australia. Adolescents (aged 12-17 years) were recruited using a two-stage procedure, consisting of an in-school screening (n=1491) followed by a diagnostic interview for those meeting screening criteria (n=218), to identify students with high levels of anxiety and sleeping difficulties, but without past or current major depressive disorder (n=144). Eligible participants were randomised into either a sleep improvement intervention (‘Sleep SENSE’) or an active control ‘study skills’ intervention (‘Study SENSE’). One hundred twenty three participants began the interventions (Female=60%; Mean Age=14.48, SD=0.95), with 60 in the sleep condition and 63 in the control condition. All participants were required to complete a battery of mood, sleep and cognitive style questionnaires, seven-days of wrist actigraphy (an objective measurement of sleep), and sleep diary entry at pre-and-post intervention. Results: The sleep intervention condition was associated with significantly greater improvements in subjective sleep (global sleep quality, sleep onset latency, daytime sleepiness), objective sleep onset latency, anxiety, pre-sleep arousal, and sleep knowledge compared with the control intervention condition, with small-medium effect sizes. Parallel multiple mediation models showed that there were bidirectional relationships between improvements in subjective sleep quality and pre-sleep arousal/global anxiety. Conclusion: The SENSE study is an efficacy trial of a selective group-based sleep intervention for the treatment and prevention of sleep and mental health problems among at-risk adolescents experiencing both sleep and anxiety disturbance. The study provides evidence, using a methodologically rigorous design, including an active control comparison condition, that a multi-component group sleep intervention that includes cognitive-behavioural and mindfulness-based therapies, can improve wakefulness in bed variables, daytime dysfunction, anxiety, pre-sleep arousal, and sleep knowledge among at-risk adolescents. The results also provide evidence that pre-sleep arousal and anxiety are particularly important for adolescents’ perceived sleep quality, and should be key targets for new treatments of adolescent sleep problems. Public Health Significance: Given the high prevalence of adolescent sleep and internalising problems, the implications of an effective adolescent sleep intervention for clinical practice and public policy are potentially significant. However, changing sleep behaviour, especially objective measures of sleep, in this age group, has been challenging. This thesis shows that the Sleep-SENSE program can improve objective and subjective indices of sleep, as well as anxiety symptoms, when compared to an active control intervention. The results also showed that reductions in pre-sleep hyperarousal represent a key psychophysiological mechanism for therapeutic improvements in subjective sleep problems among anxious adolescents, and that cognitive behavioural and mindfulness-based sleep interventions should be directed towards adolescents with vulnerability for hyperarousal. Sleep SENSE is one of the only interventions demonstrated to be efficacious in improving sleep and mental health amongst vulnerable adolescents. Furthermore, the program is likely to be cost-effective - it involves a simple screening process and a group intervention format - and could be disseminated to a wide range of clinical and non-clinical settings in primary care, mental health, adolescent health and sleep medicine, and may assist in the treatment and prevention of adolescent sleep and mental health problems. The intervention also lends itself to flexible modes of delivery (e.g., non-specialist practitioners, group settings, individual settings, school-based, internet and other e-health modes of delivery), further enhancing its translational potential.
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ItemInvestigating anxiety and depression in adults with low intellectual ability( 2016)Adults with low ability have been routinely excluded from general population research that supports cognitive behavioural therapy for anxiety and depression. Even studies using samples of adults with ability below average exclude potential participants with profound and severe intellectual disability, without testing task-specific capacity. Consequently, little is known about the viability of cognitive models of anxiety and depression amongst adults with low ability. The present study addresses this through four main lines of enquiry: inclusion of all abilities through screening and validity procedures; prevalence of signs and symptoms of anxiety and depression as well as the impact of life stressors on these; cognitions and their specificity for anxiety and depression; and the impact of anxiety and ability on attentional responses to emotional stimuli. A sample of 70 adults from each level of low ability, unselected for signs or symptoms of anxiety and depression, was recruited from community-based disability support services. Participants were screened for general (receptive language) and task-specific abilities, interviewed for symptoms of anxiety and depression and disorder related cognitions then administered a visual-probe task with emotional face stimuli. Informants provided data on signs of mental ill-health, stressful life events and adaptive behaviour. Task-specific validity procedures governed data included for analysis. The inclusionary approach meant participants from all ability levels below average were included. Task-specific screening measures were superior to receptive language in predicting validity on research tasks, especially for participants with severe and profound intellectual disability. Dimensional measurements meant ability variables could be covaried or controlled in most analyses. Mean levels of signs and symptoms were lower than those in available reference studies, as were the rates of clinical level cases. General ability was positively correlated with signs of anxiety and depression but was not related to symptoms. Similarly, the number of life events was correlated with all scales on the measure of signs but not with symptoms of anxiety or depression. The lack of concordance highlights the gap between what informants see and what respondents think and feel. Learning a person’s subjective interpretation of events can help understand their emotions and behaviour. Depressive cognitions uniquely predicted significant variance in symptoms of depression but only ability, rather than anxious cognitions, predicted anxiety symptoms. Cognitive content-specificity for depression bolsters support for the use of cognitive behaviour therapy but further research into the relationship between ability and anxiety is required. The lack of directional bias in selective attention to emotional faces in any of the anxiety or ability groups means cognitive-motivational theory was not supported but future studies should address methodological issues. Attentional control theory was supported but the slowing of emotional face processing caused by high anxiety, but not depression needs replication. Trials of attentional training may be justified to reduce anxiety. Further research into cognitive models of anxiety and depression is urgently needed and future studies should ask theoretical as well as clinical questions.