title: Examining the shared and unique relationships among substance use and mental disorders.
abstract: BACKGROUND
  Co-morbidity among use of different substances can be explained by a shared underlying dimensional factor. What remains unknown is whether the relationship between substance use and various co-morbid mental disorders can be explained solely by the general factor or whether there remain unique contributions of specific substances.
  
  
  METHODS
  Data were from the 2007 Australian National Survey of Mental Health and Wellbeing (NSMHWB). A unidimensional latent factor was constructed that represented general substance use. The shared and specific relationships between lifetime substance use indicators and internalizing disorders, suicidality and psychotic-like experiences (PLEs) were examined using Multiple Indicators Multiple Causes (MIMIC) models in the total sample. Additional analyses then examined the shared and specific relationships associated with substance dependence diagnoses as indicators of the latent trait focusing on a subsample of substance users.
  
  
  RESULTS
  General levels of latent substance use were significantly and positively related to internalizing disorders, suicidality and psychotic-like experiences. Similar results were found when examining general levels of latent substance dependence in a sample of substance users. There were several direct effects between specific substance use/dependence indicators and the mental health correlates that significantly improved the overall model fit but they were small in magnitude and had relatively little impact on the general relationship.
  
  
  CONCLUSIONS
  The majority of pairwise co-morbid relationships between substance use/dependence and mental health correlates can be explained through a general latent factor. Researchers should focus on investigating the commonalities across all substance use and dependence indicators when studying mental health co-morbidity.
authors.affiliation: NHMRC Centre for Research Excellence in Mental Health and Substance Use, National Drug and Alcohol Research Centre, University of New South Wales,Sydney,Australia.
authors.forename: M
authors.initials: M
authors.lastname: Sunderland
authors.affiliation: NHMRC Centre for Research Excellence in Mental Health and Substance Use, National Drug and Alcohol Research Centre, University of New South Wales,Sydney,Australia.
authors.forename: T
authors.initials: T
authors.lastname: Slade
authors.affiliation: Department of Psychology,University of Minnesota,Minneapolis,MN,USA.
authors.forename: R F
authors.initials: RF
authors.lastname: Krueger
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019973:Alcohol-Related Disorders / Q000453:epidemiology; D019969:Amphetamine-Related Disorders / Q000453:epidemiology; D001315:Australia / Q000453:epidemiology; D015984:Causality; D015897:Comorbidity; D005260:Female; D006801:Humans; D008297:Male; D002189:Marijuana Abuse / Q000453:epidemiology; D001523:Mental Disorders / Q000453:epidemiology*; D008875:Middle Aged; D015233:Models, Statistical; D009293:Opioid-Related Disorders / Q000453:epidemiology; D019966:Substance-Related Disorders / Q000453:epidemiology*; D055815:Young Adult
keywords: substance use disorders