The development of depression in children and adolescents with ADHD

Attention Deficit/Hyperactivity Disorder (ADHD) is a common mental health problem in childhood and adolescence, characterized by symptoms of hyperactivity, impulsivity and inattention. Apart from suffering from these symptoms, children and adolescents with ADHD also run the risk of developing other mental health problems, notable among which is depression. A depression worsens the outlook for those with ADHD, making it important to understand how it develops and so how it could be prevented. In this thesis, I describe the development of depression in adolescents with ADHD who participated in a large study with a follow-up period of over ten years, TRAILS. I found that, in adolescents with ADHD, the presence of additional mental health problems, such as anxiety and disruptive behaviour problems, facilitated the development of depression. Another risk factor for depression in adolescents with ADHD was the development of problematic peer relationships. In terms of specific brain functions and of family functioning, adolescents with both ADHD and depression were worse off than those with only one of the two problems, but I found little evidence for classifying ADHD plus depression as a separate psychiatric disorder type.