Toward an Externalizing Spectrum in DSM–V: Incorporating Developmental Concerns

Progress and innovation in DSM–V include the proposal of a new structural organization of disorders that stands to bring childhood and adult disorders together. Specifically, many common disorders would be grouped under broader dimensions of internalizing and externalizing problems. Although this distinction originated in childhood psychopathology research, current work has drawn heavily from studies with adults. The integration of common childhood disorders into the current approach remains an important task. This article reviews evidence for a structural model of externalizing pathology with a focus on research with younger populations and highlights both commonalities and distinctions that exist between externalizing dimensions in children and the externalizing spectrum in adults. The article also summarizes 3 areas that pose key questions for delineating an externalizing spectrum that better reflects developmental concerns: the incorporation of childhood disorders, the integration of temperament and personality traits, and better accounting for relevant developmental issues, including person–environment interaction, critical developmental periods, and differentiating normal and abnormal behavior. KEYWORDS—externalizing behaviors; developmental psychopathology; aggression; attention deficit ⁄hyperactivity disorder; relational aggression; DSM–V This work was supported in part by funding from the Social Sciences and Humanities Research Council of Canada. I would like to thank Joan E. Grusec and Robert F. Krueger for their helpful comments on an earlier draft of this manuscript. Correspondence concerning this article should be addressed to Jennifer L. Tackett, Department of Psychology, University of Toronto, Toronto, ON, Canada M5S 3G3; e-mail: tackett@psych. utoronto.ca. a 2010 The Author Child Development Perspectives a 2010 The Society for Research in Child Development Volume 4, Number 3 Achenbach’s seminal work on an empirically based approach to assessment of childhood psychopathology has changed the way researchers, clinicians, and educators think about childhood behavioral problems (Achenbach, 1966; Achenbach & Edelbrock, 1984). This far-reaching influence has been sustained over the past several decades and resulted in the Achenbach family of instruments, with the Child Behavior Checklist (CBCL; Achenbach & Rescorla, 2001), in particular, remaining one of the most common forms of assessment of childhood psychopathology. One of the fundamental aspects of Achenbach’s original analyses was the introduction of a hierarchical conceptualization of mental disorders (Achenbach, 1966). Specifically, Achenbach identified two broad behavioral spectra, which he labeled internalizing and externalizing, that substantially accounted for the systematic covariation among more narrowly defined behavioral problems. In addition to the enormous impact that Achenbach’s work has had on the realm of childhood psychopathology, it has also had an impact on approaches to adult psychopathology, such that a similar hierarchical organization has more recently been identified in adult populations (Krueger, 1999). While Achenbach’s hierarchical structure resulted from analyses at the item level of specific behaviors, the hierarchical structure identified in adult populations has primarily resulted from analyses on disorders as defined by the Diagnostic and Statistical Manual of Mental Disorders (DSM; American Psychiatric Association, 2000). Thus, analogous internalizing and externalizing dimensions have emerged across childhood and adult populations as well as across differential levels of analysis. Over the past decade, this area of inquiry has flourished, with numerous researchers working toward identification of common causes and correlates to these broadband domains. Indeed, research in this area has progressed to an extent that this hierarchical organization, at the core still analogous to Achenbach’s early conceptualization, has been proposed as an overarching hierarchical scheme for the next edition of the DSM, DSM–V (Andrews et al., 2008). This movement toward a dimensional