Nosology and measurement in child and adolescent psychiatry.

The last 50 years have witnessed enormous strides in the measurement and classification of child and adolescent psychiatric disorders. Debates about whether we should continue to depend upon a categorical nosology still continue, but we argue that, despite the absence of clear dividing lines between psychiatric disorders and normality and ubiquity of diagnostic comorbidity, the current official approach to nosology has served child and adolescent psychiatric research surprisingly well. In particular we point to the utility of non-developmental diagnostic criteria as tools for discovering developmental effects on psychopathology. We also maintain that the search for sharper boundaries between disorders is fundamentally mistaken. However, official nosologies have tended to privilege information collected in diagnostic interviews and to sideline observational and other methods that cannot easily be made to conform to the format of their criteria. We suggest that it is time to remedy this situation. The ICD-10 and DSM-IV are useless for children under the age of about two, while alternatives, such as the DC:0-3, suffer from a profound lack of empirical support. We suggest a way forward through the integration of methods from temperament and psychopathology research. Finally, we deplore the failure of standardized assessment techniques to have penetrated more deeply into everyday clinical assessment.