Children and young teenagers are best advised not to use drugs of any kind, not just cannabis. Young brains grow as they develop – a process termed “neuroplasticity” –  and drugs taken at a young age are bound to interfere with that process. Because of this, regardless of the need for evidence of harm, we should do what we can to prevent young people from accessing all recreational drugs and to delay the age of first use as long as possible. That is one of the strongest arguments against prohibition and in favour of cannabis law reform, it is not an argument in favour of continued prohibition which has seen the age of first use drop steadily over the years. Sadly the way this is usually reported by the tabloid press is far from objective, and indeed this lack of objectivity isn’t confined to the tabloid press.

The Today programme on Radio 4 is hardly to be compared with the lower reaches of the gutter press – like the Daily Mail for example – but this morning’s report about a new study went some way to bridging that gap. The study in question is:

Continued cannabis use and risk of incidence and persistence of psychotic symptoms: 10 year follow-up cohort study  (read it here)

The BBC coverage on today was quite clear in its message  (listen / download MP3 file here); the study and published conclusions were reported without any critical analysis which is par for the course when it comes to cannabis reporting. But toward the end of the item the studio presenter, Sarah Montague, asked the reporter, Danny shaw, what this means for the cannabis debate and how this plays into the debate about the classification of cannabis.  Danny Shaw made the following statement:

I think this adds support for the government’s – the Labour government’s – stance that it took three years ago to upgrade cannabis from class C to B. That was against the recommendation from the Advisory council on the misuse of drugs which said at the time there was a probable but weak causal link between psychotic illness and cannabis use and that cannabis played only a modest role in the development of these conditions.  It’s possible that the advisory council may have to review its findings in the light of  this research which is one of a series of studies which is really emphasising this very strong link between cannabis and psychosis.

As for the gutter press – for example the Daily Mail – their coverage was as expected, the story, headlined Cannabis use ‘doubles risk of psychosis for teenagers‘ covered all the claims of an increase in psychosis caused by cannabis and included an interesting quote from Professor (now Sir) Robin Murray

In short, it adds a further brick to the wall of evidence showing that use of traditional cannabis is a contributory cause of psychoses like schizophrenia

He didn’t explain what he meant by “traditional cannabis”, nor how this study shows any such thing and in fairness there is somewhat less than a “wall” of evidence to support the claim that cannabis actually causes serious mental illness.

In passing it’s interesting to note the Mail also emphasised the reefer madness scare by accompanying this report with a side bar story headed “Killers addiction”

Jake Fahri had been using  cannabis  since he was 12 before slashing another teenager’s throat  in ‘three minutes of absolute madness’ after a trivial row in a baker’s shop.

But enough of the Daily Mail, we expect nothing less.

The quote from Robin Murray was widely reported across the media (google search), it is perhaps a classic reefer madness soundbite of the sort the press love. So from the media’s coverage of this  can we assume the authors are supportive of prohibition? Well, it seems not. Somewhat less well reported in the UK were comments from Professor Wayne Hall from the University of Queensland and Professor Louisa Degenhardt from the Burnet Institute in Melbourne, as Science Daily reported

The major challenge is to deter enough young people from using cannabis so that the prevalence of psychosis is reduced, say experts from Australia in an accompanying editorial.

Professor Wayne Hall from the University of Queensland and Professor Louisa Degenhardt from the Burnet Institute in Melbourne, question the UK’s decision to retain criminal penalties for cannabis use, despite evidence that removing such penalties has little or no detectable effect on rates of use. They believe that an informed cannabis policy “should be based not only on the harms caused by cannabis use, but also on the harms caused by social policies that attempt to discourage its use, such as criminal penalties for possession and use.”

This, of course, throws a totally different light on the debate which is far different to the argument presented by the BBC or most of the British media and supports the statement made in the opening paragraph of this blog. In short, if cannabis is dangerous, it should be properly controlled and the trade properly regulated. So why is it that in this country the agenda is set, no debate is ever allowed and prohibition almost never questioned in the mainstream media?

The study claims to demonstrate that continued cannabis use increased the risk of a psychotic incident by nearly double. Of course, this is double a small number so it’s not a huge risk, but psychosis is a nasty illness and it does affect young people more than or adults, so clearly we do need to take some measures to protect this vulnerable group.

But is the study actually valid in its conclusions?

Imagine if a study were done into the effects of drinking and the study made no attempt to quantify what type of alcohol was being drunk – whether it was vodka or beer – and under a regime where that booze had been supplied by an unregulated illegal trade and was a highly uncertain quality product. Would anyone in their right minds draw any meaningful conclusions from such a study about the dangers of alcohol as supplied by a regulated and properly controlled trade? Of course not.

In addition to the complications created by an uncontrolled trade supplying a polluted product of unknown strength, cannabis presents another, additional unknown as a prohibited drug. Cannabis comes in many forms, containing different ratios of active chemicals (especially THC and CBD) which is thought to have a strong bearing on the mental health debate. This study made no attempt to identify the type of cannabis being used and in all honesty it couldn’t do so because of the regime of prohibition.  Worse it made no mention of these complications.

It’s also very likely the cannabis users studied smoked their cannabis with tobacco, it’s not at all clear if the study made any attempt to look only at users of pure cannabis but the word tobacco occurs only once in the paper’s text and that’s when describing the “Munich composite international diagnostic interview (DIA-X/M-CIDI)” technique. Controlling for “drugs” appears to mean

The variable use of other drugs included psychostimulants, sedatives, opiates, cocaine, phencyclidine, and psychedelic drugs

Likewise alcohol only features in the description of CIDI.

Not controlling for tobacco use is a major flaw however, because cannabis used with tobacco is often smoked to relieve a tobacco craving rather than the cannabis effect, thus leading to higher levels of use. People with psychotic illness are known to smoke tobacco at a far greater rate than people without the illness. Tobacco is not a neutral benign drug in this debate, so why wasn’t this complication even acknowledged?

The study also makes the conclusion that cannabis use comes before the onset of the illness and therefore the self medication theory is not supported. This is rather a big assumption as people developing mental illness often show “pre-morbid” indications of the illness; symptoms of an illness that hasn’t shown itself yet. An example might be finding a meaningless association of words funny, or disruptive behaviour at school. It’s never easy to spot these symptoms and indeed, they  may not be symptoms if they are seen. But self medicating cannabis use, especially unusually heavy cannabis use, caused by the developing but as yet not apparent illness may indeed be a possibility.

These are glaring errors with this study which undermines the credibility of it to a large extent. The only conclusion that can safely be drawn is surely that cannabis with tobacco used under a regime of prohibition increases the risk of psychosis for young people.

But considerations like this count for nothing with reefer madness style reporting.