An expert on drug abuse speaks on the dangers of marijuana

Thursday 22 October, 2015

The idea that a big proportion of Australians use cannabis and that legalising it will not make much difference is simply not true, according to cannabis and drug abuse expert Professor Jan Copeland.

Speaking at Warrane on Wednesday 21 October 2015, Professor Copeland said there was a common misconception, sometimes promoted by the media, that a large proportion of Australians have tried cannabis. “The media makes a strong case that everybody uses cannabis anyway and it is completely harmless,” she said. But in fact only about 35 percent of Australians had tried the drug and most of them did not use it regularly. “When we say 35 per cent of the population have tried cannabis, almost all of them tried it once or twice and that was it,” she said. “Some go through a bit of a phase. First-year university is a bit of a notorious time for people experimenting and even using it every weekend...”

Professor Copeland said there was nevertheless a proportion of users who go on to have problems. She said while one of the arguments used in favour of legalising marijuana was that many people were already using it, she could not see how legalising it would improve the situation. “If the number of people using it is a measure of failure of the current policy, how then do we measure the success of legalisation?” she said.

Professor Copeland is Director of the National Cannabis Prevention and Information Centre (NCPIC), a consortium led by the National Drug & Alcohol Research Centre (NDARC) at UNSW. She started her career working in health care for 10 years as a registered nurse and as a registered midwife. She then went on to an honours in science (psychology) degree at UNSW and then completed a PhD in Community Medicine and Public Health and has been at the NDARC since 1989, setting up NCPIC in 2007. 

She said one of the problems in the past with getting medical help for people suffering from cannabis addiction was the common perception that the drug was not physically addictive.

“Is it addictive?” she said. “I believe it is. The science very strongly says it is and we have very good laboratory models.” Professor Copeland said it was possible to get rats addicted to cannabis, even though they generally don’t like it. “It is one drug that it is hard to get them to take,” she said. “Except for adolescent rats. They love it. There is something about the adolescent brain that finds it more rewarding.”

Professor Copeland noted that if young people did not try marijuana during adolescence it is much less likely they ever would without policy or other changes. One in 10 people who have ever used it go on to develop an addiction over their lifetime, compared with one in three of those who used nicotine and one in seven or eight alcohol users.

As with most drugs,  users tended  develop a tolerance and find they need to use more and more of it to get the same effect. Over the past couple of decades, strains of marijuana had been bred to increase the level of the chemical responsible for people feeling “stoned” - THC. It had reached very high levels and was causing an increase in symptoms like paranoia and hallucinations.  “Ten to 15 years ago, marijuana was only one-to-three percent THC,” Professor Copeland said. “Now it is about 14.9 percent - at least five times stronger than what used to be on the market. “Edibles are even more dangerous. They sell them like a chocolate bar and one square can have 10 milligrams of THC, which is a very big dose. And who has one square? People end up very sick, hallucinating and tragic things can happen. “There are also new very high potency oils - wax or shatter or dab - which are almost 100 percent THC. 

“It is clearly possible to be addicted. There is a very high craving. And although it is relatively easy to get through a cannabis withdrawal - we can put a person in ward and after seven days they are over the worst of the physical symptoms - the cravings can go on for weeks, months or years. So psychological addiction is a major driver.”

Professor Copeland said she was particularly concerned about the spread of what is synthetic cannabis which was used in some places because it was not typically detected in drug tests. It doesn’t contain THC that is found in cannabis but unregulated or tested chemicals that act  on the same brain receptors.  But it could be up to 100 times more potent than natural cannabis and had caused three deaths in Australia in recent times. Some people had hallucinations that made them think they were dead. In a recent survey of Australian users, over 70 percent said they would never use it again.

Another concern was the idea that medicinal cannabis could cure cancer. “This is a real worry,” she said. “Some people are giving up (medicinal) drugs despite the fact that there are absolutely no human trials for any cancer condition. It is absolutely not supported by science.” The idea that cannabis could be a potent drug for pain relief was also not supported by clinical studies at this time but with more currently being conducted. For example, a recent study found it was no better than a placebo or standard treatment for severe chronic pain. 

Professor Copeland noted that cannabis was a drug had both the respiratory-related harms of tobacco and the intoxication-related harms of alcohol.  One of the least discussed harms was its effect on school performance with research finding  a reduction in school completion rates of 60 percent among those using before the age of 16 years.  

In the Q&A session that followed her talk, Professor Copeland was asked to comment on long-term research into the effects of marijuana. She said that the current cohort of cannabis users had not been using the drug long enough for the long-term effects to become apparent, but some were just starting to move into ages where harms like lung cancer and heart diseaseare seen in tobacco smokers. “You can’t randomise people to be cannabis smokers for 25 years,” she said, “so you can only do it with correlation research. So you look at the weight of evidence over time. “Most users haven’t been exposed to it for long enough. But it has way more toxins in it than tobacco and it can be a gateway to nicotine smoking as well.”

Professor Copeland said the question of whether marijuana could be a gateway to harder drugs was much debated argument, but it was true that most heroin users had used cannabis but few cannabis users go on to be heroin addicts. Drug use tended to change brain reward pathways permanently and predisposed users to finding other drugs more rewarding when used in early adolescence as the brain develops. They could then move on to other drugs  especially when their tolerance to a drug like marijuana increased.
 

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