Mental health in children with intellectual disability : family context and measurement

Children and young people with intellectual disability (ID) are at increased risk of mental health difficulties and emotional and behavioural problems. Using large-scale survey data and statistical modelling techniques, this thesis has been able to build on the knowledge base of emotional and behavioural difficulties in children and young people with ID. In Chapter 1, key definitions and context are discussed, along with an overview of conceptual and theoretical perspectives of child and family wellbeing and key existing literature in the field. This is followed by four empirical chapters (Chapters 2, 3, 4, and 5). Chapter 2 used structural equation modelling to explore whether parental mental health mediated the relationship between poverty and child anxiety (N = 648) using data from the first wave of the 1000 Families study and comparing anxiety in children with ID only (n = 323) to children with ID and autism (n = 325). Following this, Chapter 3 looks at the measurement of emotional and behavioural difficulties in children with ID (N = 626), examining the clinical utility of the parent-report Strengths and Difficulties Questionnaire (SDQ) in a large community sample from the first wave of the Families study. Chapter 4 uses two waves of data from the 1000 Families study to examine the bidirectional relationship between child internalising and externalising difficulties and parental mental distress, life satisfaction, and carer burden (N = 650). Building a longitudinal framework, Chapter 5 uses group-based trajectory modelling to examine the developmental trajectories of anxiety in individuals with ID from childhood to adulthood (N = 474). After these empirical chapters, the final chapter (Chapter 6) summarises and discusses the findings of the individual studies, and provides implications for theory, educational and clinical practice, and future research. In summary, the thesis showed that children and young people with ID had high levels of emotional and behavioural difficulties, but contextual factors such as socio-economic position and parental mental distress were key to understanding these findings. The SDQ had clinical utility as a brief screen of emotional and behavioural difficulties in children and young people with ID, with clear implications for research as well as educational and clinical practice. Child internalising and externalising difficulties were relatively stable over time, and longitudinal research suggested that individuals with ID followed several distinct trajectories of anxiety across development