Prevalence, Associations and Comorbidity of Cannabis Use and Cannabis Use Disorders in the Australian National Mental Health Surveys From 2007 to 2020–22

INTRODUCTION: As cannabis policies become more liberal, and products increasingly potent, it is important to monitor changes in rates of cannabis use and those at risk of harm. We used data from the largest national mental health survey in Australia to examine changes in prevalence, associations and comorbidity of past 12-month cannabis use and cannabis use disorder (CUD) from 2007 to 2020-22. METHODS: Data were drawn from the two most recent Australian National Surveys of Mental Health and Wellbeing (age range: 16-85): 2007 (n = 8841) and 2020-22 (n = 15,893). The prevalence of use and CUD were estimated and logistic regression was used to examine associations between individual characteristics and cannabis use outcomes, as well as changes in strength of association over time. RESULTS: Prevalence of recent cannabis use was stable from 2007 (6.7%, 95% CI 6.0%, 7.3%) to 2020-22 (6.7%, 95% CI 6.2%, 7.1%), as was CUD (1.0%, 95% CI 0.7%, 1.3%; 0.6%, 95% CI 0.4%, 0.8%). Respondents were significantly more likely to report CUD if they were younger (16-25 years), male, initiated cannabis use < 18 years, reported recent polysubstance use, exhibited other substance and mental disorders and had visited mental health services (OR 3.26-78.00). Compared to 2007, the association between younger age and CUD was stronger in 2020-22 (OR 2.39, 95% CI 1.20, 4.77), whereas the association between polysubstance use and CUD was weaker (OR 0.42, 95% CI 0.20, 0.91). DISCUSSION AND CONCLUSIONS: Findings suggest that population-level use and CUD may have remained stable over time, but young people may now be more vulnerable to developing CUD.