Centre for Youth Mental Health - Theses
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ItemCharacteristics and Predictors of Suicidality in Young People with Depressive Disorders( 2023)Depression is one of the most prevalent and disabling mental health conditions among young people worldwide. Suicidality and depression are closely intertwined, yet the specific factors that contribute to the nature and severity of suicidality, or changes in suicidality over time, are not perfectly understood. Factors other than depressive symptom severity, such as comorbid psychopathology and personality traits, might be important contributors. In order to reduce the burden of suicidality in young people with depression, we need to improve our understanding of its underlying constructs and contributory elements. This has the potential to contribute to improved prevention and early intervention efforts across multiple stages of suicidality, in addition to informing more targeted clinical treatment approaches. Aims and Objectives The broad aim of this research program was to contribute towards an improved understanding of suicidal thoughts and behaviours in young people with clinically diagnosed depressive disorders. More specifically, the aim was to identify modifiable intervention targets, which could inform clinical treatment approaches, and suicide prevention and early intervention efforts more broadly. Methods This research program comprises four studies each addressing different research questions. Study 1 is a comprehensive systematic review of contributors to suicidality in young people with unipolar and bipolar depression. Study 2 is an analysis of the dimensionality of a widely used measure of suicidal ideation, including associations between this measure’s latent factors and actual suicidal behaviour in young people with major depressive disorder (MDD). Study 3 is an investigation of how different dimensions of social support are associated with suicidal ideation in a treatment seeking cohort of young people with MDD; and Study 4 is a longitudinal analysis of associations between a range of psychosocial correlates and suicidal ideation severity in this same cohort of young people MDD, assessed over a 12-week period. Main Results Several key themes can be drawn from the findings of this research program. First, there is a lack of consensus regarding how the construct of suicidality should be defined, highlighting the need for international collaboration in the development of a standardised, validated classification system for suicidal ideation and suicidal behaviours. The second key finding is that suicidality in young people with depressive disorders is multidimensional in nature. That is, the way in which suicidality manifests in an individual is multifaceted. Suicidality is comprised of multiple constructs encompassing both active and passive ideation, intrapersonal cognitions such as hopelessness and lack of self-worth, and interpersonal factors such as perceived burdensomeness. The third key finding is that there are multiple determinants of suicidality in young people with depressive disorders; in addition to depressive symptoms, there are numerous other predictors of the nature and severity of suicidality. Notably, familial support is an important protective factor, while psychopathological features such as state and trait anxiety contribute to suicidality severity. Discussion Outcomes of this research program reinforce the notion that suicidality is complex and multideterminant in nature. Depression symptomatology is an important contributor, suggesting that regular monitoring of depression symptom severity should be a core aspect of the clinical management of suicidality in young people with depressive disorders. Suicidality is not driven by depression symptomatology alone and it is clear that suicide prevention and intervention efforts need to go beyond simply reducing depression severity. Psychiatric comorbidity with depression, particularly comorbid anxiety, is an important determinant of suicidality. Anxiety and depression, in particular, share many clinical features and risk factors. Interventions targeting transdiagnostic features could have clinical utility in reducing the burden of suicide in young people. In addition, methodological assessment of personality features and carefully targeted intervention approaches such as dialectal behaviour therapy, or mentalization-based therapy, could be a beneficial component of the clinical management of depression and suicidality in young people. An important clinical implication of this research program is that there is likely substantial variability underlying the mechanisms for suicidality from one depressed young person to the next. This suggests that there is perhaps a similarly high degree of variability with respect to potentially effective treatment targets for suicidality. It raises the question of how useful it is to consider a diagnosis of depression as a specific risk factor for suicidality in young people. Alternative approaches to identifying aetiological mechanisms of suicidality, such as a specific symptom approach, could be warranted. It is crucial to develop and employ early intervention approaches for suicidality in young people which focus on the earliest stage of suicidality. Potential targets for early intervention, such as increasing adaptive social support to reduce severity of suicidal ideation, are likely to be beneficial in preventing transition to suicidal behaviour. This highlights the need to assess and monitor suicidality early in young people presenting with mental health symptoms, irrespective of the specific diagnosis. This requires the use of age-appropriate suicidality assessment tools designed for use in young people. Given the fluctuating nature of suicidality, real-time symptom monitoring could perhaps be implemented as part of routine clinical care. The use of transdiagnostic interventions aimed at modifying common cognitive processes underlying depression, anxiety, and suicidality could be an effective treatment approach. Although suicidality is a complex phenomenon and no single approach to prevention or intervention is likely to be universally effective, the findings of this research program do have the potential to help reduce the suicidality-related health burden in this particularly vulnerable population.
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ItemAntecedents of incident bipolar disorder in youth( 2017)Background: Bipolar disorder (BD) is a serious mental illness characterised by episodes of mania and depression. The disability associated with this disorder and the observation that at least a sub-proportion have a progressive course suggests that early or preventive interventions may be an effective strategy to minimise the disability. However, prevention efforts for BD require characterisation of targets for such interventions. Aims and objectives: Thus, the overall aim of this research program was to describe the pre-onset illness stages related to the development of incident (hypo)manic episodes and their associated functional impairment. Specifically, we aimed to examine clinical populations where preventive efforts may be more feasible. The objectives included identification of i) baseline characteristics associated with later BD among non-bipolar help-seeking youth; ii) rates and predictors of transition from major depressive disorder (MDD) to BD in previously published studies; iii) instruments that have prospective predictive validity in identifying BD and iv) the precursors of functional impairment in the post-illness period. Methods: This thesis comprises five studies that have examined these issues using diverse methodologies – using systematic review, meta-analyses and longitudinal cohort designs. Three studies involved examining baseline characteristics associated with the development of later BD from non-bipolar states. One study identified the instruments that have been used to predict the later onset of BD using a systematic review, while the final study examined the pre-onset predictors of later functioning among young people with first episode BD. Main results: The characteristics associated with later BD in the two cohort studies included subthreshold manic symptoms, comorbid substance use, severity of depression, antidepressant use and lower functioning. Meta-analyses identified that family history of BD, comorbid psychotic symptoms and lower age of onset of depression was predictive of transition from MDD to BD. The systematic review identified few instruments with prospective validity for predicting BD onset that had been replicated in clinical cohorts. However, instruments with validity in non-clinical cohorts, or those without replication were described. Across the first four studies, combinations of risk factors were associated with a greater risk of transition to BD. Poor premorbid adjustment in the pre-onset phase was predictive of later functioning among youth with first episode mania. Discussion: The findings of these studies point to the need to use combinations of risk factors identified using validated instruments, particularly in young people to predict the onset of BD. This may then help develop preventive interventions that may be tested in studies that are feasible and have adequate statistical power. Incorporating functional precursors into pre-illness stages may help with prevention of functional impairments. A putative instrument which may decrease measurement bias is also proposed. The primary limitation of the included studies was in the post-hoc nature of analyses and the associated lack of availability of all possible baseline confounders. Additionally, low statistical power limited the ability to examine certain associations. Future studies should examine multiple confounding variables in longitudinal cohorts of youth and young adults. Larger cohorts that are enriched for multiple risk factors may help improve statistical power.
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ItemPromotion of self-help strategies for sub-threshold depression: an e-mental health randomised controlled trial( 2012)Background: Sub-threshold depression refers to clinically relevant depressive symptoms that fall short of a diagnosis of major depression. Sub-threshold depression is very common in the general population, impairs functioning, increases the risk of developing major depression, and poses a significant burden at the population level. Public promotion of greater use of effective self-help strategies for depression has been proposed as one technique to reduce this population burden. Improving self-help strategies could reduce symptoms of sub-threshold depression and prevent major depression. Depression experts have identified several self-help strategies that are helpful for sub-threshold depression. The aim of the study was to develop messages based on these strategies that could be promoted to members of the public with sub-threshold depression, and to test whether their promotion was effective. Method: Twelve email messages (‘Mood Memos’) were developed, based on self-help strategies endorsed as effective and feasible by depression experts. The email messages were developed with reference to theories of behaviour change, persuasion, and health communication, in order to persuade recipients to engage in the self-help behaviours. The effectiveness of these emails was evaluated in a randomised controlled trial. Recruitment was via internet-based sources and participants joined the study by visiting the website www.moodmemos.com. Adults aged 18+ with sub-threshold depression who were not receiving professional treatment for depression were eligible to participate. Participants were randomly allocated to receive emails twice weekly for six weeks in a fully automated intervention. The active group received emails based on the effective self-help strategies and the control group received emails containing general information about depressive disorders. Assessment points were at baseline, midway through the intervention and at the end of the intervention (6 weeks post-baseline). The primary outcome was depression symptom score on the Patient Health Questionnaire-9 (PHQ-9). Secondary outcomes were psychological distress, assessed with the ten-item Kessler Psychological Distress Scale (K10), and level of functioning, assessed with the Work and Social Adjustment Scale. The primary hypotheses were that the emails containing self-help strategies would reduce depression symptoms and reduce the incidence of major depression more than the control emails post-intervention. Results: The study recruited an international sample of 1,326 adults with sub-threshold depression. There was a small, significant difference in depression symptoms post-intervention, favouring the active group (Cohen’s d = 0.17, 95% CI: 0.01 to 0.34). There was also a higher, though non-significant, risk of major depression in the control group (Relative Risk = 1.32, 95% CI: 0.89 to 1.98). A similar effect was found for psychological distress (d = 0.22, 95% CI: 0.05 to 0.38), but effects on functioning were less strong, with no significant difference between the active and control groups (d = 0.12, 95% CI: -0.05 to 0.28). A mediation analysis indicated that the effect of the emails on depression symptoms was completely mediated by the use of the self-help strategies promoted in the emails. Discussion: Overall, the results indicate that promoting effective self-help strategies to the public via automated emails was effective for sub-threshold depression. The improvement in depression was associated with use of the self-help strategies promoted in the emails. The delivery of self-help messages via email is a scalable, easily disseminated intervention. The study is a novel contribution with potential to reduce the large population burden of depression.