title: Theoretical and observed subtypes of DSM-IV alcohol- and cannabis-use disorders in the Australian population.
abstract: OBJECTIVE
  Using a polythetic combinatorial approach to diagnosing substance-use disorders according to Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), criteria inevitably leads to substantial clinical heterogeneity in the manifestation of these disorders. Not all theoretically possible combinations of symptoms are found in reports from North American samples. Cross-cultural differences in substance use and dependence make it important to consider patterns of problematic use in other countries.
  
  
  METHODS
  The heterogeneity of DSM-IV alcohol- and cannabis-use disorders in Australia was explored by calculating the number of theoretically possible subtypes for these disorders based on the DSM-IV diagnostic criteria and identifying which of these subtypes are observed in the 1997 National Survey on Mental Health and Wellbeing.
  
  
  RESULTS
  Of the theoretically possible subtypes, 55.6% were observed for alcohol dependence, 73.3% for alcohol abuse, 61.9% for cannabis dependence, and 53.3% for cannabis abuse. Four subtypes, containing only one criterion each, accounted for 87.5% of individuals with alcohol abuse. Fourteen subtypes characterized 70% of participants with alcohol dependence. One subtype, use in physically hazardous situations, accounted for 75.7% of individuals with cannabis abuse. Eight subtypes represented 72.3% of individuals with cannabis dependence.
  
  
  CONCLUSIONS
  Alcohol and cannabis abuse appear to be homogeneous disorders, whereas alcohol and cannabis dependence are heterogeneous disorders, in Australia. All of the DSM-IV diagnostic criteria for substance dependence contributed to understanding the symptoms associated with these disorders among Australians. The importance of not making major decisions regarding the type and number of diagnostic criteria for a given disorder based on analysis of data from a single country was highlighted.
authors.affiliation: School of Psychology, University of Ulster Magee Campus, Northland Road, County Londonderry, BT48 7JL, Northern Ireland. o.mcbride@ulster.ac.uk
authors.forename: Orla
authors.initials: O
authors.lastname: McBride
authors.forename: Maree
authors.initials: M
authors.lastname: Teesson
authors.forename: Tim
authors.initials: T
authors.lastname: Slade
authors.forename: Andrew
authors.initials: A
authors.lastname: Baillie
mesh_terms: D000437:Alcoholism / Q000145:classification* / Q000175:diagnosis / Q000208:ethnology*; D001315:Australia / Q000208:ethnology; D003431:Cross-Cultural Comparison; D003625:Data Collection / Q000379:methods; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D006801:Humans; D008297:Male; D002189:Marijuana Abuse / Q000145:classification* / Q000175:diagnosis / Q000208:ethnology*; D008962:Models, Theoretical; D011159:Population Surveillance / Q000379:methods; D011897:Random Allocation