Conceptualisation, assessment and treatment of Anhedonia in adolescent depression

Anhedonia, the loss of interest and/or pleasure in previously enjoyable experiences is a core symptom of Major Depressive Disorder. It is associated with depression severity, relapse and poor treatment outcome. Despite this, little is known about how this symptom is experienced by adolescents. Most current psychological treatments for depression do not target anhedonia and for young people there are no adequate measures of this symptom for use in research or treatment. This thesis aims to explore adolescents’ experiences of anhedonia, to critically evaluate the available anhedonia self-report measures and to develop a self-report measure that can be used by therapists and researchers to develop effective ways to reduce anhedonia in young people. Paper 1 explores adolescents’ experiences of anhedonia. Semi-structured interviews about the experience of anhedonia were conducted with 34 adolescents with a primary diagnosis of depression (n = 12) or elevated depressive symptoms (n = 22). Next self-reported measurements of anhedonia were examined. Paper 2 presents a systematic review and critical evaluation of the psychometric properties of 14 self-report anhedonia scales, which highlights limitations in their psychometric properties and relevance for adolescents. Following on from this, Paper 3 describes the development and validation (n = 2098) of an adolescent specific self-report measure of anhedonia developed based on adolescents’ experiences of anhedonia defined in Paper 1. Lastly, the treatment of adolescent anhedonia was explored in Paper 4. In this qualitative study, adolescents’ (n = 8) experiences of Brief Behavioural Activation (BA) for depression, a treatment development to enhance positive reinforcement and increase engagement in valued activities, were explored with a focus on understanding its impact on anhedonia. Taken together, these findings have implications for understanding, assessing and treating the symptom of anhedonia during adolescence in both clinical and research settings