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.
Method: 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.