Understanding the determinants and socioeconomic inequality of behavioural and mental health problems, and services utilization among Australian adolescents

Behavioural and mental health problems are considered to be among the most important global public health concerns in the 21stcentury. Worldwide, the burden of behavioural and mental health issues is rapidly escalating, and this burden is part of the global burden of disease (GBD), including Australia. The responses to the growing burden of behavioural and mental health have been scarce, particularly among adolescents, owing to inadequate knowledge of the long-term effects of behavioural and mental health, and their consequences. Moreover, empirical evidence is lacking about how the social determinants (including inequality) of behavioural and mental health interact and bring about the utilization of mental health services in adolescents. Hence, the overarching aim of this thesis by publication is to investigate the burden of behavioural (bullying victimization) and mental health problems (mental disorders, self-harm, and suicidality) among adolescents aged 12-17 years of Australia. Moreover, the thesis aims to identify key social determinants of behavioural and mental health issues (bullying, victimization, mental disorders, self-harm, and suicidality), and mental health services. This thesis also investigates how the social determinants interact within the behavioural and mental health issues, and to what extent social determinants contribute to the inequity associated with bullying, victimization, mental disorder, self-harm, and suicidality, and in the utilization of mental health services for adolescents of Australia. To achieve the research goal, this PhD thesis by publication followed a typical format: eight empirical papers (which are to be published in peer-reviewed journals) bookended by substantial introductory and concluding chapters. This thesis is formulated on the basis of Erikson’s theory of psychosocial development, Andersen’s Behavioural Model of Service Utilization, ecosocial theory, and the World Health Organization (WHO) recommended Commission on Social Determinants of Health (CSDH) conceptual framework. It is based on a quantitative approach, using a nationally representative cross-sectional dataset from the second Australian Child and Adolescent Survey of Mental Health and Wellbeing: Young Minds Matter (YMM). This thesis is constructed using three main research themes: (I) Identifying the indicators of behavioural and mental health problems in adolescents (Studies 1-3); (II) Assessing mental health services utilization among adolescents with behavioural and mental health issues (Studies 4-6); and (III) Measuring socioeconomic inequality in behavioural and mental health problems and the utilization of mental health services among adolescents (Studies 7-8) in Australia. The thesis reveals that the prevalence of bullying, victimization, mental disorders, self-harm, and suicidality is especially high among Australian adolescents, although many adolescents with behavioural and mental health problems do not access any mental health services. The results show that a variety of sociodemographic factors are associated with behavioural and mental health problems (bullying, victimization, mental disorders, self-harm, and suicidality) together with the use of mental health services. Further, the thesis finds that bullying victimization can be indicators for mental disorders, self-harm and suicidality in adolescents. Moreover, mental disorders such as depression and anxiety disorder, in particular, have a mediating effect on the association between bullying victimization and health risk behaviours (self-harm and suicidality) in adolescents. In addition, this thesis reveals that socioeconomic disparities exist in behavioural and mental health, showing that adolescents from low-income families reported more bullying victimization, mental disorders, and suicidal behaviour than those from middle-and high-income families. The results also show that health services (e.g., general practitioners, psychiatrists, psychologists, community clinics) are more likely to be accessed by adolescents from economically worse-off families in comparison to their counterparts, implying pro-poor inequalities. in contrast, online services are found to be mostly used by adolescents from high-income families compared with adolescents from low-income families. Furthermore, the current thesis provides a better understanding of the social determinants (including inequality) of behavioural and mental health, and the use of mental health services among adolescents in Australia. Additionally, the findings of the thesis will help healthcare providers, researchers, academics, and policymakers to take new initiatives and implement effective prevention and evidence-based intervention programs to reduce the burden of behavioural and mental health problems and increase the use of mental health services among adolescent with mental health problems in Australia