CATEGORICAL MODELS OF CHILDHOOD DISORDER - A CONCEPTUAL AND EMPIRICAL-ANALYSIS

In this review we explore the clinical and scientific status of catego rical models of childhood disorder. Three themes are developed. First, the practical origins of standardised category-based diagnostic schem es are examined along with their contemporary philosophical and psycho logical significance. Next, the impact that these systems have had on the science of child psychopathology is explored. We look at their lin k to the medical model and the assumption that childhood disorders are categorical, endogenous, and dysfunctional in nature. We argue that t hese assumptions underpin the dominant paradigm in child psychopatholo gy and so constrain empirical study and theory development. In the fin al section, the different ways in which researchers have responded to this link and its impact on science are presented. We present the sort of scientific realism associated with Meehl (1995) as the most approp riate basis for a philosophically respectable child psychopathology. F ollowing this approach means unpacking the paradigmatic assumptions, i ncluding the assumption of the categorical structure of disorder, into hypotheses that are then put to empirical test. The sorts of data tha t would allow us to test the categorical hypothesis are identified. We conclude by discussing the results from three recent studies using be haviour genetic analysis of twin data that, in fact, lead us toward a rejection of this hypothesis. The implications for diagnostic and clin ical practice of such a rejection are discussed.