Helping Youth Make Sense of Cannabis

We have all heard a variety of claims about cannabis. Some are scary, like, “cannabis causes psychosis” or “cannabis leads to brain damage and dropping out of school.” Others tell a different story, “cannabis is a miraculous herb that alleviates the symptoms of everything from hiccups to Multiple Sclerosis.”

Making sense of these competing claims can be confusing . While there is at least some truth in almost all of them, accurate and balanced information about cannabis is more complex than simple statements. It is particularly important for young people to realize that there are no simple answers. People are complex beings. Cannabis use can affect  us all differently, but it has potential to impact our minds, bodies, relationships and future prospects.

So where do we begin? We need to acknowledge that all drugs can be both good and bad. Even medications recommended by a doctor can cause harm. Since all drug use carries some risk, it is important to learn how to weigh the potential benefits against the potential risk. Fortunately, human beings have been doing this for a long time. And the wisdom of the ages might be summed up as, “not too much, not too often, and only in safe contexts.” Using more of a drug (or a higher strength preparation) or using daily as opposed to once in a while is more dangerous. But risk is also linked to a wide range of contextual factors. Age – the younger a person is when they start using cannabis regularly, the more likely they are to experience harms in the short term or later in life. But other factors, like where and with whom one uses, also impact risk. Smoking cannabis on school property or driving under the influence are examples of particularly high-risk contexts for quite different reasons.

The reasons why we might use cannabis are also important, and they influence the balance of risk and benefit. If our use is motivated only by curiosity, for example, our use will likely be only occasional or experimental. On the other hand, if our use is about fitting in with a particular group or a way to cope with anxiety or some other mental health problem, we are more likely to develop a more regular and riskier pattern of use. Yet again, if we are consciously choosing to use cannabis to address troubling symptoms related to various health challenges, we may find it relatively easy to manage our use in a way that minimizes risk.

While it may be helpful to know the various potential risks and benefits associated with cannabis use, the more important issue is to become consciously aware of our own pattern of use and our reasons for using or not using. As human beings, we tend to “outsource” control of our behaviour to the environment. For example, when we are with our friends, we may talk a certain way. But when we are talking with our parents, our teachers, our boss – without thinking about it – we slip into a different way of talking. Drug use is more dangerous when we allow it to become a pattern that we don’t think about.

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Author: Dan Reist, Assistant Director (Knowledge Exchange) at the Centre for Addictions Research of BC

Cannabis and psychosis: Is there evidence of causal association?

It has been well known since historic times that cannabis may cause a variety of psychiatric symptoms. In fact, the desire to take cannabis or marijuana is primarily to obtain mental effects, and the line may be thin even in an occasional user between experiencing a pleasant and exciting psychoactive effect and a real psychotic episode. “Cannabis psychosis” is a term widely used for psychotic episodes resulting from cannabis use. These occur during or shortly after intake and may last days or weeks, but subside after discontinuation of the drug. They may require hospitalization and medication. Comprehensive summaries of mental health effects of cannabis have been published by Murray and Hall & Degenhardt.

It has often been debated whether use of cannabis can cause long-term psychotic states, and in particular schizophrenia and other chronic psychoses. Seeing patients with a combination of heavy cannabis use and schizophrenia, I was intrigued to assess the causal direction of the association. It was in the 1980s when I found out there was a survey on drug use in a national cohort of 50,000 Swedish 18-19 year old male conscripts (one year of military service was compulsory in Sweden until 2010) that we could link to data on occurrence of schizophrenia later in life. We found that those who reported use of cannabis in adolescence had a doubled risk of schizophrenia compared to those who did not use cannabis. With data on social background, psychological characteristics, and psychiatric condition assessed at conscription, we could control for such factors that might influence the association.

We have continued to follow this cohort and the men are now over 50 years old. The contribution of cannabis to new cases of schizophrenia has declined in occasional users but those who reported heavy use of cannabis in adolescence still have a twofold increased risk of schizophrenia, even at older ages. We do not know whether this is due to continued use of cannabis, or whether heavy early use could indeed have had very long lasting effects.

In recent years, several other studies have also found an association between cannabis use and later onset of chronic psychosis. A review was published in 2007 concluding that there is now “sufficient evidence to warn young people that using cannabis could increase the risk of developing a psychotic illness later in life.” The paper was accompanied by an editorial in which the prestigious journal the Lancet admitted that they had previously underestimated the risk of harmful effects of cannabis.

We recently studied the pattern of care of the patients with schizophrenia in our cohort of male conscripts, and it turns out that those patients with a history of cannabis use had double the number of total days in hospital and around double the number of hospitalizations that were twice as long in duration of those who did not have a history of cannabis use.

Thus, there is now evidence that cannabis is indeed a contributory cause of chronic psychoses, including schizophrenia. Certainly, cannabis is not the only cause of chronic psychosis. There generally needs to be other factors, such as genetic factors, personality characteristics, etc. to cause schizophrenia or other long-standing psychoses. It has been shown that the risk of psychosis in cannabis users is especially strong in psychologically vulnerable persons. Thus young people, and especially persons with mental health illness, should be warned about the risk of chronic psychotic disorders as an effect of cannabis use. Not only because of the risk of chronic psychosis, but also a number of other negative physical and mental side effects.

*Please note that the material presented here does not necessarily imply endorsement or agreement by individuals at the Centre for Addictions Research of BC

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Peter Allebeck, Professor of Social Medicine, Karolinska Institute, Stockholm, Sweden