Editorial: Progress Toward an Elaborated Externalizing Spectrum in Youth.

The conceptualization of psychopathology has begun to shift from a proliferation of discrete categorical diagnoses to a parsimonious set of hierarchically organized dimensions, such as in the Hierarchical Taxonomy of Psychopathology (HiTOP).1 This shift is driven by mounting evidence of substantial within-diagnosis heterogeneity and rampant cross-diagnosis comorbidity.2 This hierarchical structural approach represents a progression of increasing breadth and generality from individual symptoms to symptom dimensions to lower-order factors to higher-order psychopathology dimensions or spectra. These spectra include thought disorder, neurodevelopmental disorders, internalizing, and externalizing, all of which have received considerable support for their reliability and validity.3-6 These spectra are thought to encompass a range from normative personality traits and cognitive functions to the maladaptive extremes of psychopathology. Indeed, this continuity is critical for conceptualizing these higher-order dimensions as spectra.