Cannabis use and dependence among Australian adults: results from the National Survey of Mental Health and Wellbeing

Aims. To examine: (i) the prevalence of cannabis use and DSM-IV cannabis de pendence among Australian adults, and (ii) correlates of level of cannabis involvement. Design. Cross-sectional survey assessing substance use and DSM -IV substance use disorders (abuse and dependence). Setting and participant s. A household survey of a nationally representative sample of 10 641 Austr alians aged 18 years and older. Measurements. Trained interviewers administ ered a structured, modified version of the Composite International Diagnost ic Interview (CIDI). Findings. In the past 12 months, 2.2% (95% CI: 1.8, 2. 6) of adults were diagnosed with DSM-IV cannabis use disorder, comprising c annabis dependence (1.5%; 95% CI: 1.2, 1.8) and cannabis abuse (0.7%, 95% C I: 0.6, 0.8). Almost one-third of cannabis users (31.7%; 95% CI: 27.7, 35.7 ) met criteria for cannabis dependence (21%; 95% CI: 16.7, 25.3) and abuse (10.7%; 95% CI: 8.0, 13.4). Multinomial logistic regression revealed that c ompared to non-dependent cannabis users, non-users were more likely to be f emale, aged 25 + years, out of the labour force and married/de facto, and d isplayed lower levels of co-morbidity. In contrast, dependent cannabis user s were more likely to be 18-24 years old, unemployed, and displayed higher levels of co-morbidity than non-dependent users. Conclusions. Cannabis use disorders affect approximately 300 000 Australian adults. A better understa nding of the factors associated with cannabis dependence may help identify groups who have difficulties controlling use and aid the development of str ategies for reducing cannabis-related harm.