The number of Australians presenting for hospital treatment with cannabis-related problems has jumped by nearly a third since 2002 according to a study from the National Drug and Alcohol Research Centre (NDARC).
The study published online in Addiction found that although the overall number of Australians using cannabis has declined, the rate of harmful use, including daily use, has increased markedly since 1995, particularly among 40 to 49 year olds. Older users were twice as likely to report daily use compared to the 14 to 19 year age group. But younger daily users (aged 14-19) were significantly more likely than older users to use 10 or more cones or joints a day. Of the younger daily users, 63 per cent reported difficulties controlling their use.
Around nine per cent of Australians have smoked cannabis in the past year, down from 11 per cent in 2004. This decline has also been mirrored among school students, with cannabis use more than halving among this group over the last decade – from 32 per cent in 1996 to 14 per cent in 2005. But problems associated with use rose over this period.
The number of older users presenting to hospital with dependence and other cannabis related problems has increased markedly over the past five years and has nearly doubled among users aged 30-39. Hospital presentations for cannabis-induced psychosis were highest among the younger users aged 20-29. Overall the number of hospital outpatient treatment episodes for cannabis problems climbed from 23,826 in 2002 to 31,449 in 2007 – a 30 per cent increase.
The study analysed data from several sources covering the period 1993 to 2007, including the National Drug Strategy Household Survey and the National Hospital Morbidity Database.
Study lead author Amanda Roxburgh said the decline in overall cannabis use in Australia, if taken alone, ignores a worrying trend of increasingly harmful use.
“There is good evidence that daily or near daily use by adults can lead to the development of dependence and regular use is also associated with an increased risk of psychosis. Also the earlier someone starts using cannabis the more likely they are to develop problems including dependence later on.
“This is borne out by our figures. We are seeing younger cannabis users smoking at harmful levels – 10 or more cones or joints a day – and then when we look at the hospital presentations we are seeing large numbers of younger users present to hospital with acute problems such as cannabis-induced psychosis.
“With older users, we are seeing an increase in hospital presentations for conditions such as dependence, consistent with sustained patterns of cannabis use for prolonged periods of time.”
Professor Jan Copeland who heads the National Cannabis Prevention and Information Centre (NCPIC) said that the study highlighted the need for more prevention and education around high risk patterns of use, particularly among younger people.
“The significant drop in the number of Australians using cannabis may be indicative that prevention and education messages aimed at the general population have been successful, and we need to continue to focus on the prevention of cannabis initiation among young people,” says Professor Copeland.
“What is of ongoing concern is the number of young people who are reporting heavy harmful use and we need to trial more programs aimed at preventing and treating regular heavy use among this group.
“We also know that only a small minority of people seek early treatment for their cannabis use. This may reflect a lack of awareness of treatment for dependence and a lack of awareness of the harms related to regular cannabis use.”
The study conducted by Amanda Roxburgh and colleagues from the National Drug and Alcohol Research Centre at the University of New South Wales reviewed data from 1993 – 2007 collected in the National Drug Strategy Household Survey; the Australian Secondary Student Alcohol and Drug Survey; the National Hospital Morbidity Database and the Alcohol and other Drug Treatment Services Minimum Dataset. It is published online in Addiction March 2010.
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