Modeling psychopathology structure: a symptom-level analysis of Axis I and II disorders

Background. Analyses of co-morbidity patterns among common mental disorders have repeatedly indicated that relationships among disorders can be understood in terms of broad superordinate dimensions. However, these analyses have been based on syndromal-level indicators, which are often heterogeneous, rather than on symptoms, which are presumably more homogeneous. Method. Symptom-level exploratory and confirmatory analyses were used to explore the joint hierarchical organization of Axis I and II psychopathology, using data on 8405 individuals from the 2000 British Psychiatric Morbidity Survey. Results. Analyses indicated that 20 identified subordinate dimensions of psychopathology could be organized into four broad superordinate dimensions: Internalizing, Externalizing, Thought Disorder, and Pathological Introversion. Conclusions. These results extend existing model frameworks 'downward' as well as 'outward by analyzing symptoms rather than diagnoses, and by integrating symptoms from Axis I and II disorders in a common framework. This model demonstrates the importance of hierarchy in psychopathology structure, comprises replicable features of psychopathology structure, and has important implications for understanding the nature and organization of mental disorders.