Introduction

Until recently, mood disorders were thought to have their onsets in adulthood and to be rare in children and adolescents. This view failed to take into account the possibility that the clinical presentations of mood disorders might differ with age. Research now has shown that mood disorders do occur in children and adolescents but present somewhat differently than in adults (Bowring and Kovacs, 1992; Birmaher et al., 1996). Recognition of this phenomenon has stimulated the use of neuroimaging techniques for research in these disorders; clinical applications have not been established.

This chapter will first present the clinical characteristics of these disorders in children and adolescents, briefly reviewing what is known about the neurobiology of these disorders; it will then present an overview of both adult and pediatric imaging studies of relevance to mood disorders.

Clinical aspects of mood disorders in children and adolescents

Child and adolescent mood disorders are complex in both their clinical presentations and neurobiology. These disorders commonly involve cognitive, affective, vegetative, and perceptual systems. The underlying neurobiology appears to involve multiple neurotransmitter and neuroendocrine systems. The developmental course and presentation vary, depending upon the age of the patient and what other disorders are comorbid. Bipolar disorders are particularly complex because often their initial presentation is a severe, sometimes psychotic, depression that later evolves into episodes of mania or hypomania. One of the hallmarks of pediatric bipolar disorders is mood lability and marked irritability.

The development of mood and its disorders occurs at much younger ages than was previously thought.