16 October 2009
Australians have the dubious honour of being among the world’s top cannabis users, an international review shows (Lancet 2009; 374:1383-91).
United Nations Office on Drugs and Crime data revealed that cannabis users accounted for 3.9 per cent of the global population aged 15 to 64 years in 2006, with the highest use in Australia, New Zealand and the USA, followed by Europe.
A review of the adverse health effects of cannabis by lead author Professor Wayne Hall, from the school of population health at the University of Queensland, showed Australia was in the highest use category with more than 8 per cent of the population aged 15 to 64 years using cannabis annually.
The review showed the lifetime risk of dependence in cannabis users was around 9 per cent and highlighted recent evidence estimating cannabis use caused 0.2 per cent of the total disease burden in Australia.
Cannabis use was associated with major adverse effects, including a higher risk of motor vehicle accidents.
Australian research analysing tetrahydrocannabinol (THC) blood concentrations in 1420 drivers killed in car accidents found cannabis users were twice as likely to be culpable than non-users. Cannabis use was also associated with impaired respiratory function and adverse cardiovascular effects, particularly in adults with existing cardiovascular disease.
Regular cannabis use was also shown to affect adolescent psychosocial development and mental health, particularly in users with a history of psychotic symptoms or a family history of psychological disorders.
“The most probable adverse psychosocial effect in adolescents who become regular users is impaired educational attainment,” the authors said.
Last Reviewed: 16 October 2009