Neuroimaging of treatment effects in developmental neuropsychiatric disorders

Introduction As has been reviewed in Section 2 of this volume, neuroimaging studies are beginning to delineate those brain systems involved in a wide range of developmental psychopathology. Regions involved in a functional domain (attention, impulse control, mood regulation, etc.) are found to be altered in children with a psychiatric disorder relative to a control group. From a treatment perspective, the question is whether such differences constitute a “biomarker, ” a biological characteristic that is objectively measured and serves as an indicator of disease processes or responses to a therapeutic intervention (Frank and Hargreaves, 2003; Wise and Tracey, 2006) (see Table 21.1). Importantly, both pharmacological and psychosocial interventions can alter biomarkers. Biomarkers need not relate directly to etiology of the disease. Take for example the clinical use of a chest radiograph. A patient with pneumonia presents with fever, shortness of breath, and infiltrates on the radiograph. The pneumonia might be viral, bacterial or due to a toxic substance. The infiltrate represents the location and seriousness of the compromised lung function independent of etiology. Treatment of the underlying condition will lead to resolution of the infiltrate, thus making the radiograph valuable in monitoring treatment effects. It is likely that the first clinical uses of neuroimaging in pediatric mental disorders will parallel this example in which the utility is tied to monitoring treatment effects. Pediatric neuroimaging studies implicate many of the same brain regions in multiple disorders.