title: The effects of latent variables in the development of comorbidity among common mental disorders.
abstract: BACKGROUND
  Although numerous studies have examined the role of latent predispositions to internalizing and externalizing disorders in the structure of comorbidity among common mental disorders, none examined latent predispositions in predicting development of comorbidity.
  
  
  METHODS
  A novel method was used to study the role of latent variables in the development of comorbidity among lifetime DSM-IV disorders in the National Comorbidity Surveys. Broad preliminary findings are briefly presented to describe the method. The method used survival analysis to estimate time-lagged associations among 18 lifetime DSM-IV anxiety, mood, behavior, and substance disorders. A novel estimation approach examined the extent to which these predictive associations could be explained by latent canonical variables representing internalizing and externalizing disorders.
  
  
  RESULTS
  Consistently significant positive associations were found between temporally primary and secondary disorders. Within-domain time-lagged associations were generally stronger than between-domain associations. The vast majority of associations were explained by a model that assumed mediating effects of latent internalizing and externalizing variables, although the complexity of this model differed across samples. A number of intriguing residual associations emerged that warrant further investigation.
  
  
  CONCLUSIONS
  The good fit of the canonical model suggests that common causal pathways account for most comorbidity among the disorders considered. These common pathways should be the focus of future research on the development of comorbidity. However, the existence of several important residual associations shows that more is involved than simple mediation. The method developed to carry out these analyses provides a unique way to pinpoint these significant residual associations for subsequent focused study.
authors.affiliation: Department of Health Care Policy, Harvard Medical School, 180 Longwood Avenue, Boston, MA 02115, USA. kessler@hcp.med.harvard.edu
authors.forename: Ronald C
authors.initials: RC
authors.lastname: Kessler
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Cox
authors.forename: Jennifer Greif
authors.initials: JG
authors.lastname: Green
authors.forename: Johan
authors.initials: J
authors.lastname: Ormel
authors.forename: Katie A
authors.initials: KA
authors.lastname: McLaughlin
authors.forename: Kathleen Ries
authors.initials: KR
authors.lastname: Merikangas
authors.forename: Maria
authors.initials: M
authors.lastname: Petukhova
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Pine
authors.forename: Leo J
authors.initials: LJ
authors.lastname: Russo
authors.forename: Joel
authors.initials: J
authors.lastname: Swendsen
authors.forename: Hans-Ulrich
authors.initials: HU
authors.lastname: Wittchen
authors.forename: Alan M
authors.initials: AM
authors.lastname: Zaslavsky
mesh_terms: D000293:Adolescent; D000328:Adult; D001008:Anxiety Disorders / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology*; D015897:Comorbidity; D003430:Cross-Sectional Studies; D039721:Diagnostic and Statistical Manual of Mental Disorders; D006306:Health Surveys; D006801:Humans; D007389:Internal-External Control; D008137:Longitudinal Studies; D001523:Mental Disorders / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology*; D008875:Middle Aged; D008960:Models, Psychological; D015233:Models, Statistical; D019964:Mood Disorders / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology; D015999:Multivariate Analysis; D019966:Substance-Related Disorders / Q000175:diagnosis / Q000453:epidemiology* / Q000523:psychology*; D014481:United States; D055815:Young Adult