The epidemiology of cannabis use and cannabis-related harm in Australia 1993-2007

Aims To examine trends in patterns of cannabis use and related harm in the Australian population between 1993 and 2007. Design Analysis of prospectively collected data from: (1) the National Drug Strategy Household Survey (NDSHS) and Australian Secondary Student Alcohol and Drug Survey (ASSADS); (2) the National Hospital Morbidity Database (NHMD); and (3) the Alcohol and Other Drug Treatment Services National Minimum Dataset (AODTS-NMDS). Participants Australians aged 14 years and over from the general population; students aged 12-17 years; public and private hospital in-patients; public and private in-patients and out-patients attending for drug treatment. Measurement Prevalence of 12-month cannabis use among the general population and secondary students. Proportions in the general population by age group reporting: daily cannabis use; difficulties in controlling cannabis use; and heavy cannabis use on each occasion. Number of hospital and treatment presentations for cannabis-related problems. Findings Prevalence of past-year cannabis use has declined in the Australian population since the late 1990s. Among those reporting past-year use, daily use is prevalent among 40-49-year-olds, while heavy patterns of use are prevalent among 14-19-year-olds. Hospital presentations for cannabis-related problems reflect similar trends. Past-year cannabis use has decreased among the 10-19-year age group, but those who are daily users in this age group report using large quantities of cannabis. Conclusions Despite declines in the prevalence of cannabis use, continued public health campaigns warning of the harms associated with cannabis use are essential, aimed particularly at users who are already experiencing problems. The increasing demand for treatment for cannabis problems in Australia suggests the need for more accessible and more effective interventions for cannabis use disorders.