Introduction

An episode of clinical depression during childhood or adolescence has a negative impact on social, academic and family functioning, as well as being associated with an increased risk for recurrence (McCauley & Myers, 1992) and impairment in social-emotional functioning that extends into adult life (Harrington et al., 1990). Efforts to identify effective prevention and treatment strategies for depression in children are ongoing (Myers & McCauley, 1997). Prevention and treatment approaches need to be informed by a developmentally sensitive understanding of the mechanisms that underlie the onset of depression in young people.

Understanding the underpinnings of clinical depression is a complex task, which must include consideration of a multitude of factors. Depression is not simply a disorder of mood regulation but involves alterations in physiological and cognitive functioning. Moreover, the study of depression requires careful attention to developmental issues, especially the challenges of adolescence. While the general incidence of psychopathology increases only moderately during the adolescent years, the frequency of depression increases significantly, particularly in females (Rutter et al., 1976; Lewinsohn et al., 1993; Hankin et al., 1998). Furthermore, recent research suggests a discontinuity between prepubertal and postpubertal depression. Depression which first presents during the prepubertal period appears to be more strongly linked to environmental factors while postpubertal depression is best explained by a model of interaction between genetic and environmental factors (Thapar & McGuffin, 1996). More importantly, prepubertal depression represents a strong, but nonspecific risk for adult adjustment problems whereas adolescent depression is strongly linked to recurrent depressive episodes during adult life (Harrington et al., 1996).