Introduction

The emergence of newer, noninvasive approaches to brain research since the 1980s, for example magnetic resonance spectroscopy (MRS) and functional magnetic resonance imaging (fMRI), has provided findings of critical relevance to childhood-onset anxiety disorders. These techniques are particularly well suited for studying pediatric populations where radiation exposure limits the use of positron emission tomography (PET) and single photon emission computed tomography (SPECT). This chapter will discuss the use of these techniques in childhood-onset anxiety disorders.

For many years, investigations in adult psychiatric disorders have been extended to child populations with the intent of verifying the finding in children in a “top-down” fashion. In the process, the developmental focus was often lost. Recent investigations have kept the developmental focus at the forefront, while applying a systems neuroscience approach to childhood-onset neuropsychiatric disorders, including pediatric anxiety. Understanding the underlying neutral substrate of childhood-onset anxiety disorders requires knowledge of the normal functional development of the brain. Recent investigations have begun to refine and map systematically the developmental trajectory of brain functions in normal children and to apply this knowledge to the study of childhood-onset neuropsychiatric disorders (Casey et al., 1995, 1997b; Rosenberg et al., 1997a,b; Rosenberg and Keshavan, 1998). The techniques of fMRI and MRS provide in vivo noninvasive approaches for studying neural circuitry in childhood anxiety disorders. Moreover, these techniques permit delineation of critical developmental “windows” of abnormality in brain anatomy and function in pediatric anxiety disorders.