Back to top

[ Skip to main content ]

Date published: 27th November 2013 | Type: Media release

Wayne Hall

People who use cannabis generally under appreciate how easily they could become dependent and often mistakenly believe the drug has no real health risks, the New Zealand Drug Foundation's Cannabis and Health Symposium was told today.

Professor Wayne Hall, from the University of Queensland, said epidemiological studies over the last 20 years had firmly established cannabis dependence as a significant problem.

“What’s clearest is that there are a lot more people seeking help for cannabis dependence than there ever have been, and this is equally true in places where the drug has been decriminalised – so it’s not just a result of compulsory treatment coming from law enforcement.“In Australia, for example, the figures for those seeking help are very close to the figures for those wanting treatment for alcohol dependence.”

He said around 9 percent of cannabis users develop a dependence problem, which is very significant considering how many people use the drug. But the risks are much higher (one in six or around 17 percent) for people who start smoking cannabis in early adolescence. Regular, daily users have a 33-50 percent chance of becoming dependent.

He said early users of cannabis are also much more likely to suffer the adverse health effects of cannabis use, which are now much better understood and more common that originally thought.

These include respiratory or cardiovascular problems, psychosis and poor performance school. Recent New Zealand evidence from the Dunedin cohort study, for example, showed chronic cannabis users had an average IQ of eight points below their peers.

“In 1993 we knew cannabis impaired cognitive and psychomotor function, but we didn’t know to what extent or whether theses effects were permanent or reversible,” Professor Hall said.

“But we now have neuro-imaging evidence that heavy cannabis use can physically alter structures in the brain responsible for those types of functions.”

Professor Hall concluded by saying we need to keep researching the health effects of cannabis, find better ways of treating cannabis dependence and better ways of educating young people about its risks.

The Cannabis and Health Symposium runs from 27-29 November and seeks to broaden New Zealand’s discussion of issues around cannabis such as recent research about its effects, whether there is a need for cannabis law reform and the best ways of addressing cannabis-related harm.

Check out these related articles: See more articles

meth contamination thumbnail

Lessons must be learnt from meth report

The report into HNZ’s response to "methamphetamine contamination" contains hard lessons for the government and its agencies. The harms cause......

Read More
meth contamination thumbnail

Practical advice for homeowners and landlords on meth testing

Worried about meth contamination? Should you test for meth resudue, and what if a test comes up positive? And what does it mean for your in......

Read More

Don't delay acting on synthetic cannabinoids

Winston Peters warns Government officials to take urgent action to stop further deaths from synthetic drugs...

Read More
MoS Nov 2018 thumbnail bordain

Once an addict always an addict, right?

Chloe King uses her own addiction and recovery experience to issue a forthright challenge to some of the common ‘armchair diagnosing’ belief......

Read More
Share:
e substance newsletter promotional thumbnail
Subscribe to email updates

Get regular news, analysis and commentary on drugs issues in New Zealand. Free.

Sign up now!

Did You Know resources thumbnail
Talk drugs with young people

Did You Know helps you talk with a young person about drugs -- videos, posters and conversation starter.

Get started