Abstract
PURPOSE OF REVIEW: Although numerous studies have examined the latent structure of internalizing and externalizing mental disorders, the effects of this structure in predicting the development of comorbidity have remained unexamined until recently. RECENT FINDINGS: A novel approach to study the effects of latent internalizing and externalizing predispositions to the development of comorbidity was used to analyze data from 14 countries in the WHO World Mental Health Survey Initiative. Pervasive significant positive associations were found between temporally primary and secondary internalizing and externalizing disorders in survival analyses, with time-lagged associations consistently stronger within domains than between domains. The vast majority of these associations were explained by latent internalizing and externalizing variables. Specific phobia and obsessive compulsive disorder were the most important internalizing components and hyperactivity disorder and oppositional-defiant disorder the most important externalizing components. Several intriguing residual time-lagged associations remained significant, though, even after controlling latent predispositions. SUMMARY: The latent variable model suggests that common causal pathways account for most comorbidity among internalizing-externalizing disorders. These pathways should be the focus of future research on the development of comorbidity, although isolation of consistent residual time-lagged associations between certain pairs of primary-secondary disorders is also important in pointing the way to subsequent focused study.