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Friday 16 August 2019 11:18am

Jude Ball image
Jude Ball

New research from the University of Otago, Wellington, has shed light on the declining use of cannabis use by teens.

Researcher Jude Ball says cannabis use has fallen across all socioeconomic and ethnic groups of students in high schools, with the biggest declines seen in Māori, younger students and those in low decile schools.

The research, published in the New Zealand Medical Journal today, comes ahead of next year's referendum on legalising personal cannabis use.

Ms Ball says there has been a long term decline in lifetime cannabis use among high school students, from 38 per cent in 2001, to 23 per cent in 2012.

The proportion of teens who use cannabis weekly, or more often, halved, from 6.7 per cent to 3.2 per cent over the period. In contrast, weekly cannabis use in the adult population remained relatively stable, at about five per cent of the population in 1998 and 2007/2008, and just under four per cent in 2012/13, according to Ministry of Health figures.

Ms Ball says not only are teenagers less likely to use cannabis, but they are increasingly staying away from alcohol, tobacco and other drugs too.

“The proportion of students who reported they had never used other psychoactive drugs increased over the study period from 89 per cent in 2001 to 95 per cent in 2012.”

She says the decline in drug taking in adolescents is welcome news, with regular cannabis use associated with a range of adverse health impacts, especially in adolescents.

“Early age of initiation (under 16 years of age) particularly in combination with alcohol and/or tobacco use is associated with greater risk of psychosis, addiction, poor educational outcomes and long-term functional impairment, so preventing or delaying cannabis use is important.”

Ms Ball says the decline in cannabis use among teens is surprising given our increasingly liberal attitudes towards cannabis, but is in line with trends overseas.

“Studies suggest that adolescent cannabis use is influenced by tobacco and alcohol trends, so tighter regulations on tobacco and alcohol use may play a role in mitigating the potential harm of cannabis liberalisation for teenagers.”

With New Zealanders to vote on legalising personal cannabis use in a binding referendum at the 2020 general election, Ms Ball says it is vital that any law changes minimise the risk of increasing youth cannabis use.

“Despite recent decreases, New Zealand adolescents are still much more likely to smoke cannabis than teens in Australia or England, so there is no room for complacency.”

The study is based on an analysis of data from the Youth 2000 National Youth Health and Wellbeing surveys undertaken in 2001, 2007 and 2012 by the Adolescent Health Research Group at the University of Auckland.

This latest research paper 'Declining adolescent cannabis use occurred across all demographic groups and was accompanied by declining use of other psychoactive drugs, New Zealand, 2001-2012' is published in the New Zealand Medical Journal.

For further information contact:

Ms Jude Ball
Research Fellow
Department of Public Health

Co-author of the research paper
Associate Professor Terryann Clark (Ngāpuhi)
School of Nursing, University of Auckland

Cheryl Norrie
Communications Adviser
University of Otago, Wellington
Mob +64 21 249 6787

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