The Space of Common Psychiatric Disorders in Adolescents: Comorbidity Structure and Individual Latent Liabilities

Objective To construct a virtual space of common adolescent psychiatric disorders, spanned by factors reflecting major psychopathological dimensions; and to locate psychiatric disorders in that space, examine whether the major psychopathological dimensions can be hierarchically organized, and determine the distribution of the latent scores of individuals in the space spanned by those dimensions. Method Exploratory factor analyses of data from the National Comorbidity Survey Adolescent Supplement (NCS-A) using the psychiatric diagnoses as indicators were used to identify the latent major psychopathological dimensions. The loadings of the disorders on those dimensions were used as coordinates to calculate the distance among disorders. The distribution of individuals in the space was based on the latent scores on the factors reflecting the major psychopathological conditions. Results A model with 3 correlated factors provided an excellent fit (Comparative Fit Index [CFI] = 0.97, Tucker-Lewis Index [TLI] = 0.95, the root mean squared error of approximation [RMSEA] = 0.008) for the structure of disorders and a 4-factor model could be hierarchically organized, ultimately yielding a general psychopathology factor. Distances between disorders ranged from 0.079 (between social phobia and generalized anxiety disorder [GAD]) and 1.173 (between specific phobia and conduct disorder [CD]). At the individual level, there were 546 distinct liabilities observed (22% of all 2,455 potential liabilities). Conclusion A novel way of understanding psychiatric disorders in adolescents is as existing in a space with a limited number of dimensions with no disorder aligning along 1 single dimension. These dimensions are hierarchically organized, allowing analyses at different levels of organization. Furthermore, individuals with psychiatric disorders present with a broad range of liabilities, reflecting the diversity of their clinical presentations.