Seminal work on the underlying meta-structure of comorbidity among common mental disorders [13] indicated that many common mental disorders can be considered indicators of latent dimensional propensities to experience two types of psychopathology: internalizing or externalizing. The externalizing dimension is characterized by antisocial personality disorder and alcohol, nicotine, and drug dependence. The internalizing dimension is often divided into two sub-dimensions, one involving distress (major depression, dysthymia, generalized anxiety) and the other involving fear (panic, social phobia, specific phobia). This meta-structure has been replicated numerous times. New 2011 NESARC studies expanded our understanding of the metastructure by examining whether the association of risk factors with individual psychiatric disorders could be better expressed in terms of the latent internalizing/externalizing dimensions, and whether cross-dimension associations between disorders could be better expressed in terms of the internalizing/externalizing dimensions, and expanded the range of disorders analyzed in the meta-structure.
