“Skunk-like Cannabis Causes 24% of New Psychosis Cases” or So Mainstream Media Will Have You Believe …

Schizophrenia, Psychosis and Cannabis

The only person I know who has ever been diagnosed with schizophrenia is tee-total and claims never to have used illegal drugs and to only ever have been a non-smoking light drinker. It is a story I often think about when people tell me about cannabis causing schizophrenia. This sort of limited, completely unverifiable and one sided piece of anecdata is absolutely useless when discussing society wide issues, yet this kind of personal account is again and again used by newspapers like the Daily Mail (albeit more emotionally) whenever they need evidence of the deadly epidemic of Killer Skunk Psychosis sweeping our nation. Consequently, I think we are all familiar with “tragic and heartbreaking” tales from a middle class family about a son or daughter whose likely very normal adolescent use of cannabis (probably alongside alcohol and tobacco and who knows what else) was suddenly directly responsible for every problem that family ever suffered. Won’t someone think of the children? Otherwise, someone might think to blame the parents.

It is interesting to note that despite the Daily Mail’s reporting, Britain has some of the lowest rates of Schizophrenia in the world. http://en.wikipedia.org/wiki/Epidemiology_of_schizophrenia#By_country

The world schizophrenia rate remains roughly comparable. There are no huge spikes or variations from country to country, rather a more general trend that the Western world has a slightly lower rate than other parts of the world. If we are to believe that cannabis smoking is the number one way to develop schizophrenia we have to believe it to be true everywhere. The Netherlands, home of the coffee shop and a sensible decriminalisation policy does have a rate of schizophrenia very slightly higher than the UK. However it also has if anything a slightly lower rate of cannabis use. http://en.wikipedia.org/wiki/Annual_cannabis_use_by_country

Cannabis use has famously increased since the sixties, surely we would have been aware of a huge increase in mental illness growing steadily over the years? It has become common for well-meaning figures to shrug their shoulders and wring their hands and gently point out that perhaps the pro legalisation movement was onto something once, but not any more, not now, now that Killer Skunk is on the streets, inside every classroom, a fast tracked gateway to madness, heroin addiction, death and worse! This too is a laughable attitude to take as Dr Ben Goldacre points out, the information behind these claims is cherry picked, exaggerated and often just made up. http://www.badscience.net/2007/03/reefer-badness/#more-389 It seems bizarre that our parent's generation, those original hippies, would fall for the same repackaged reefer madness -as that is all this new media storm truly is.


A quick note on Skunk and some of the ideas mentioned by Dr Goldacre –Skunk is the name of a hybrid strain created from several different sets of landrace cannabis genetics bred together. These genetics have made their way into some but not all of the popular strains now available today. Skunk as a term used by politicians and the media refers to any high potency (in terms of THC) herbal cannabis.  There are no qualifying characteristics beyond that. Whereas we would characterise types of alcohol by a particular strength of volume, ingredients and methods of production, if a teenager or young person is in danger of smoking cannabis and it is at least quite strong (a subjective description) it must be skunk, otherwise it is nice safe hash and definitely not something dirty like soap bar. Such brilliant logic has made it harder and harder to talk about cannabis due to the false distinctions around it.

The biggest scandal around cannabis (and indeed several other drugs) is not that our laws are too permissive but that the advice and information around cannabis is flawed. The reality of cannabis use whether recreational or medical is overwhelmingly positive –people simply would not do it, write songs about it, talk about it, risk arrest over it, or move around the world for it. It is connected to ordinary people and celebrities, men and women, people from all walks of life and backgrounds. When it is so transparent to young people that the worst consequences for use come from the law (“Drugs ruin lives! If we catch you with drugs, we are going to ruin your life!”) rather than as direct side effects of its consumption, it undermines the credibility of the education around cannabis, other drugs and other subjects young people might learn about from school or the government. This is yet another way that prohibition harms society, by undermining trust in what should be legitimate information sources, young people are forced into the arms of the black market and hearsay. Once you have learned that one education policy is not true why should you have faith in any other?

If cannabis is a gateway drug that is addictive, that causes psychosis, that leads only to trouble there would not be the case that one in three of us in the UK have taken drugs (usually cannabis) –and that proportion is gradually increasing. http://www.theguardian.com/society/2014/oct/05/-sp-drug-use-is-rising-in-the-uk-but-were-not-addicted If a large proportion of cannabis users were suffering from self-induced mental illness society would break down, the fault lines would be felt across the country, there would be less unverifiable hearsay in the paper -the consequences would be everywhere. But according to the Daily Mail even occasional exposure can have terrible consequences http://www.dailymail.co.uk/news/article-471106/Smoking-just-cannabis-joint-raises-danger-mental-illness-40.html Shock headlines always sell papers, though if cannabis was a person the degree of inaccuracy around the reporting of cannabis would surely leave some parts of the media open to fairly straightforward libel cases.

It is strange that the Daily Mail and other parts of the media are so keen to attack cannabis, especially when it is so easy to find information about other much more readily abused legal psychoactive drugs.



The cause of this article is that this week, another study has emerged linking cannabis use among young people to schizophrenia. (Incidentally, this is also the week that Prince Charles has been hinted at being a toker by Will Self. http://www.theguardian.com/books/2015/feb/12/charles-the-heart-of-a-king-catherine-mayer-review-will-self) Counter articles have immediately appeared alongside the original reporting of the study pointing out that the authors of the study in no way assert that there is a causal association between cannabis use and schizophrenia. Likewise, there are any number of other scientific studies suggesting the opposite to the study, that cannabis use is harmless or even therapeutic for mental illnesses such as schizophrenia.

I can quite happily believe that cannabis might be bad for some people (in the same way I know people who cannot drink coffee or anything else caffeinated or who instantly become a mess if they drink alcohol) and in some cases may even exacerbate an existing health problem but these cases are very much in the the minority. There are few things that are suitable for everyone, but the ridiculous presentation of myths and opinions as fact so as to frighten people, inform policy and to deliberately undermine science are ultimately far more dangerous to young people and society than dried pieces of plant matter. Criminal records, social stigma and exposure to black markets along with a lack of credible advice on harm reduction is what really causes problems.

Harm Reduction

Anti cannabis studies are consistently discredited by more rigorous scientific examination or revealed not to be impartial due to having been funded by an anti cannabis lobby in the first place, or indeed to having been deliberately misinterpreted by journalists desperate for a headline, the best thing for a cannabis user and advocate to do is to counter nonsense whenever it is heard and to share sensible harm reduction advice when able. We know that mixing tobacco in joints is bad for you as it means that you end up smoking tobacco -which really is dangerous in a lot of different very serious ways. If you don't have access to a vapouriser then think about cooking with cannabis, smoking it pure, buying or growing the best quality cannabis and therefore medicine that you can. Stay away from unpredictable, dangerous legal highs that claim to emulate cannabis and take pride in knowing what you are putting in your body.

Finally though, lets consider the idea that in a small number of users high potency cannabis really does cause psychotic episodes or consistently makes existing mental health problems worse. What is the solution to this problem? I think its two part. It is up to discerning users to choose cannabis that has been grown carefully and has been well flushed before being cut down and dried. Likewise to select strains where there is a good balance between THC (presently seen as the more dangerous compound -not completely fair but lets run with it for now) CBD and other components.

The other part of the harm reduction solution is the long overdue ending of prohibition. Prohibition is a system which actively incentivizes criminal producers to make the cheapest and most dangerous product -maximum profit, lowest risk and no oversight on quality. If a cannabis user was able to confidently choose between something massively tipped towards excessively heavy amounts of THC or something more balanced or scaled more towards CBD then surely this would be a better system? A system with choice, a system where standards on how things are cultivated and produced. A system where users can ask questions and receive good and accurate information. A system where users have the option and guidance to choose weed with high CBD and anti-psychotic traits. A system where organised crime does not benefit and general society does. Due to the prevalence of cannabis use across society the reaction to terrifying headlines about mental illness should not be a fear of cannabis or reactionary new policies to increase penalties, instead these headlines should be met head on with anger, why are we not being given a choice? Why does the government continue to choose such a dangerous system on our behalf? Until the time comes where they make a new choice it is up to every user to challenge misinformation around cannabis and make sure that there are clear voices responding online and in person to every untruth published.

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  • Alex

    This is a fantastic article. Backing up any point with facts, unlike the majority of anti-cannabis articles which will just pick holes out of things to try and make a point. All round great read.

  • Shaun

    In regards to the link between use of strong herbal cannabis and mental illness , I say cum hoc ergo propter hoc. Perhaps some people use “skunk” to relieve symptoms of mental illness.

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