Last week saw a familiar pattern of activity across all newsfeeds related to cannabis. A study from Ontario suggested that cases of schizophrenia had tripled in young men with Cannabis Use Disorder (CUD).
This news exploded across tabloid media. Like Chinese whispers, the headlines moved further and further away from what the study actually showed. This is to be predicted in the Daily Mail and similar publications but much more disturbing is that some medical professionals also jumped on the bandwagon. Mary Cannon, the notorious anti-cannabis Irish psychiatrist, claimed that this is categoric proof that cannabis causes schizophrenia at a terrifying rate. In fact she said in a radio interview that nearly 20% of all schizophrenia cases are caused by cannabis.
This is nonsense. The study did not show what Cannon claimed nor what the newspapers published. Firstly it said nothing about the cause of schizophrenia. It showed only correlation, not causation. Secondly, it showed that the incidence of schizophrenia did not increase after the legalisation of cannabis for medical use in 2001, nor after the legalisation for adult use in 2018. Perhaps most significant it also showed that the overall incidence of schizophrenia was stable throughout the period of the study.
Few publications and certainly not the tabloids open themselves to fact-checking by providing their source but the study in question is available in full here.
There was also the usual list of limitations on the study which specifically warn against drawing rash conclusions but which are never referred to by the media. In this case, no account was taken of income, educational attainment, family history of mental health disorders or genetics, all factors which are known to have confounding effects on results.
Of course, the study does have some value but only within its very narrow parameters and this is where the problem lies. Irresponsible publications draw wild, hysterical conclusions more generally and even more irresponsible clinicians, who quite definitely know better, do the same thing.
We expect tabloids to sensationalise ‘for clicks’ or increased readership but more and more we see medical professionals with a political agenda distorting evidence and misleading the public.
I should make the usual disclaimers myself here. None of this is to say that cannabis is harmless and it is well established that it may increase the risk of mental health problems. It would be astonishing if a psychoactive substance couldn’t affect mental health. As ever, common sense suggests moderation, preventing use by children and policymakers should take action to control and regulate the substance and access to it.
Common sense is the key here. Unfortunately, when medical professionals start to deliver what are essentially political messages, it becomes very difficult for the average person to make a common-sense judgement. Mary Cannon, the psychiatrist referred to earlier, is an extreme case. You may as well take advice from Peter Hitchens on cannabis as listen to her but what is more worrying is when such misinformation is more widespread from those we regard as experts.
The definition of CUD is an issue in itself. As with most mental health conditions this derives from DSM-V. That is the Diagnostic and Statistical Manual of Mental Disorders, now in its fifth edition, created by the American Psychiatric Association. This is put together by psychiatrists, mostly academics, which defines mental illnesses and gives guidance on diagnosis and treatment. It is based solely on their own opinions which are informed by clinical experience. It’s important to understand that there is no objective test for this guidance or any aspect of psychiatry. It is an entirely self-referencing speciality.
In its earlier editions, DSM referenced cannabis intoxication, cannabis withdrawal, cannabis psychosis, cannabis anxiety and sleep disorders, cannabis addiction, cannabis abuse, cannabis dependence and other conditions. These have now all been combined into CUD. And of course, your average psychiatrist or doctor regards all this as fact, as their bible, It’s difficult to cut through this to any wider or alternative understanding.
There is some value in the definition of CUD and if you think you or someone you know may have a problem with cannabis, it provides useful guidance. In reality, though, it would be difficult to be a regular consumer of cannabis, either for pleasure or medicine and not be captured by this definition.
Definition of Cannabis Use Disorder (CUD)
A problematic pattern of cannabis use leading to clinically significant impairment or distress, as manifested by at least 2 of the following, occurring within 12 months:
- Cannabis is often taken in more significant amounts or over a longer period than was intended.
- Persistent desire or unsuccessful efforts are attempted to cut down or control cannabis use.
- A great deal of time is spent in activities necessary to obtain cannabis, use cannabis, or recover from its effects.
- A craving or a strong desire or urge to use cannabis exists.
- Recurrent cannabis use results in failure to fulfil role obligations at work, school, or home.
- Continued cannabis use, despite having persistent or recurrent social or interpersonal problems caused or exacerbated by the effects of cannabis.
- Important social, occupational, or recreational activities are given up or reduced because of cannabis use.
- Recurrent cannabis use even in situations in which cannabis is physically hazardous.
- Cannabis use continues despite knowledge of having a persistent or recurrent physical or psychological problem that is likely to have been caused or exacerbated by cannabis.
- The tolerance increases, defined by either (1) a need for markedly increased cannabis to achieve intoxication or desired effect or (2) a markedly diminished effect with continued use of the same amount of the substance.
- Having a withdrawal, as manifested by either (1) the characteristic withdrawal syndrome for cannabis or (2) cannabis is taken to relieve or avoid withdrawal symptoms.
So use this information wisely, moderated by your own experience and knowledge and what you can learn from other experts who are not constrained by their professional education.
Of course, doctors and scientists are just as much subject to the torrent of misinformation about cannabis over the past 50 to 100 years as anyone else. Your GP will have seen or heard about all the Daily Mail scare stories themselves and they will have helped to form opinions. This is why there remains so much opposition to cannabis amongst doctors, even for medical use. This is why our major institutions such as the NHS and the Royal Colleges still hold such outdated, disproportionate attitudes and why it will be a long time before we can get the members of NICE committees to agree that the NHS should be funding cannabis prescriptions.
