Attention Deficit Hyperactivity Disorder (ADHD) Diagnosis In Children And Adolescents: Trends And Outcomes

Abstract

With increasing prevalence rates of ADHD throughout the developed world, there is growing debate about whether this trend is due to an actual increase in prevalence, better detection and diagnosis leading to improved outcomes, misdiagnosis, or diagnosis of ADHD in youth with mild or borderline symptomatology in which diagnosis does not improve outcomes (also known as overdiagnosis). While the evidence for overdiagnosis in many other conditions (especially in screen-detected cancers) is increasingly recognised, it has proven difficult to evaluate for ADHD. In this thesis a published framework for recognising the potential for overdiagnosis is used to investigate trends in diagnosing ADHD in children and adolescents – both globally and specifically in Australia. Further, potential harms and benefits associated with an ADHD diagnosis are explored by examining long-term outcomes. Results from a systematic scoping review show how a continuum of behaviours can lead to an endless supply of potential new cases and present some of the benefits and harms that may be associated with diagnosing children and adolescents with ADHD. Subsequently, the thesis presents data from two large population-based cohorts of Australian children to illustrate how increased diagnosis rates occur in children with high-risk as well as borderline and low-risk behaviours. Building on this, an emulated randomised controlled trial applies new epidemiological methods to observational data, showing that an ADHD diagnosis may not be associated with improved quality of life in teenagers. The thesis concludes with an analysis describing the context of the overarching issue of overdiagnosis and labelling of children and adolescents with ADHD, considering the evidence of benefits and harms and explores changes and further research needed to move forward.