It’s time to take stock of the dangers posed by the present cannabis trade, not only in terms of the potential role in the development of mental illness, but also in terms of the contamination issue.
As a result of the previous blog, UKCIA was sent the full text of the paper from Marta Di Forti et al (thanks for that). It is, in all honesty a very easy study to criticise which is probably why it’s hidden behind a pay wall on the RCPsych site, with only a brief abstract available to the public. It really doesn’t stand close examination.
The selection of the control group seems OK, which was one of the concerns expressed here last week.
Particular attention was directed to attempting to obtain a control sample similar to the patient sample in age, gender, ethnicity, educational qualifications and employment status.
Although the size of the sample is still small. However the main failure of the study is in its conclusion caused by the selective – one might argue deliberately selective nature of the investigation:
All participants were asked about their use of illicit drugs and those who reported ever using cannabis were interviewed using the Cannabis Experience Questionnaire. This allows a detailed assessment of lifetime patterns of cannabis and stimulant use, including age at first use, frequency and duration of use, and the specific type of cannabis used.
No consideration seems to have been given to the use of legal drugs, especially alcohol and tobacco.
Why the focus only on illegal stimulant and cannabis use to the apparent exclusion of everything else? This is important for several reasons:
1: Alcohol and tobacco are, like cannabis, widely available and commonly used, whereas other illegal drugs are arguably less so. Heavy use of either alcohol or tobacco by the patient group would indicate a tendency to use drugs heavily in general.
2: People with psychiatric illness often have problems with alcohol which is accepted role in being a cause of psychosis. It is very possible that alcohol use would be just as common in this group as heavy cannabis use.
3: People with psychiatric illness are often heavy tobacco smokers, was there a difference in the use of tobacco by the patient and control groups? Tobacco is often entwined with cannabis use and heavy tobacco users are likely to be heavy cannabis uses simply by virtue of their tobacco use. Cannabis/tobacco users – including healthy ones – often smoke a spliff in order to satisfy a tobacco urge. Heavy cannabis use may therefore be a function of the tobacco addiction more prevalent in the patient group.
Any significant difference in the use of alcohol and tobacco between the two groups (patients and control) would, of course, invalidate the conclusions the study makes about heavy cannabis use in large part.
The authors do write
Logistic regression was used to analyse the relationships between various aspects of cannabis use (lifetime use, age at first use, duration and frequency of use, and cannabis potency) and case–control status, and to test for interaction effects while controlling for potential confounders.
Yet they seem to have defined the confounding factors in such a way as to ignore the most obvious. Other studies illustrate this point clearly, for example: The association between psychosis and problematical drug use among Australian adults: findings from the National Survey of Mental Health and Well-Being by LOUISA DEGENHARDT and WAYNE HALL
Ninety-nine persons (1·2 %) screened positively for psychosis. Regular tobacco, alcohol and cannabis use were much more common among persons screening positively, as were alcohol, cannabis and other drug use disorders. Among alcohol and cannabis users, psychosis ‘cases’ were much more likely to be dependent. Ordinal logistic regressions revealed that regular tobacco use, cannabis and alcohol dependence, and opiate abuse were predictors of psychosis scores.
So as regards heavy drug use this study told us nothing we didn’t already know. But the wider use of the most common drugs linked to mental health disorders are simply not mentioned at any point in the paper as possible confounding factors, instead it seems to point the finger at cannabis alone.
This criticism is not intended to deny that heavy use of cannabis is detrimental to those with mental illness but the question remains: is the tendency of people with mental illness to use drugs heavily the reason the heavy use of cannabis was seen? Indeed is the heavy use of drugs in general prior to the emergence of the illness what psychiatrists call a “pre-morbid indication” – a warning sign of a developing illness?
Another problem with the study is the way it assessed the type of cannabis used by the two groups. It asked which type of cannabis users “preferentially used”, it didn’t ask which type they actually used. It is very likely that both groups used what is commonly available, which is the “skunk” type cannabis. The difference in types of cannabis used is possibly therefore less significant than the authors seem to claim.
The biggest surprise comes with the age of first use results. It has long been argued by psychiatrists that early exposure to cannabis would result in a higher incidence of psychosis, yet the study does not seem to have found this correlation. Somewhat illogically the study concludes
Patients experiencing a first episode of psychosis were not more likely … to have started doing so earlier than the control group. This is not surprising because cannabis consumption is very common among adolescents in the UK
It could be argued, if there is indeed an increased risk for young people as is usually claimed, that the failure to detect a difference in the age of first use indicates a methodological fault with the study, it certainly shouldn’t be dismissed so glibly and is an interesting, if inconvenient (for the researchers) finding.
It would seem to be a very easy to make the criticism that the authors had a theory and so constructed an experiment designed to prove that theory. This is a very serious charge to make and calls into doubt the objectivity of the research group and by extension the Royal College. It really should not be as easy as this to find such an obvious fault with a study like this.
Further, the very real conclusion which might be possible to draw from this study had it included tobacco use would be the need for a safer use campaign aimed at cannabis users as UKCIA has long demanded; a campaign aimed at dissuading people using tobacco to smoke cannabis called Tokepure.
In passing it is interesting to note how tobacco use, even heavy tobacco use, doesn’t seem to be included as a substance misuse issue in much of the psychiatric literature – tobacco, apparently, is not a real drug to many psychiatrists. In fact it’s the one constant substance misuse disorder that runs through most – if not close to all – substance abuse issues. The vast majority of people with a substance misuse problem are tobacco smokers, usually heavy tobacco smokers, as are people with mental illness. Tobacco use is one of those elephants in the room that no-one likes to mention for some reason.
However, non of the above is intended to dispute the conclusion that so-called “skunk” is low in CBD and therefore likely to be a bigger risk. This warning should act as a wake-up call to the authorities.
As Deborah Orr wrote in the Guardian
The Institute of Psychiatry has published research that links skunk and psychosis, and those who champion drug use are the least willing to accept its findings. This is quite the wrong approach. If you wish for the drugs debate to move forward, then scientific evidence of the dangers of drugs is to be welcomed. Danger alone is not a reason for illegality, or cars, electricity and alcohol would be illegal, not to mention people. Danger is a reason for regulation, which an illegal market cannot deliver. What cannabis users need is a safer alternative than whatever it is that they happen to be able to score, especially if the market-leading illegal offer is particularly virulent.
UKCIA would echo that comment absolutely. Sadly and in a way that was only to be expected the prohibition campaigners have jumped on this study as final proof of the need for stronger prohibition, not helped by the NHS quoting the Daily Mail
Smokers of the strong ‘skunk’ variety of cannabis are seven times more likely to experience psychosis, according to the Daily Mail.
It must be true then, but the NHS article does make this point:
Although the study reported to have assessed the use of other stimulants, it is unclear which specific drugs were asked about or whether alcohol use was assessed.
The prominence in the supply chain of “skunk” is a product of the economic regime created by prohibition in the same way that moonshine and bathtub gin were the product of American alcohol prohibition. If this research is taken at face value it is a strong argument for law reform and not one in support of continued prohibition. It is important to emphasise that “potency” – defined here to mean the relative concentration of THC to CBD is not the same as “strength” which we will define as amount of drug per gramme of sample. If this is a confusing distinction see this blog for more details of the argument.
Another major issue for cannabis law reform campaigners has been contamination for some time. However, the issue of potency (THC/CBD ratio) remains even if the cannabis is diluted with other substances. The situation we see with street supplies these days is one of widespread contamination of both so-called “skunk” and hash. This blog has recorded several past examples of observed contamination of herbal cannabis including with lead particles and with Viagra type drugs and the case of glass beads and Soapbar is very well documented. Even Talk to Frank has noticed the last two examples.
Over the past year UKCIA has heard many reports of herbal cannabis which burns badly, leaving a hard, oily ash, it’s a subject much discussed on the forum. UKCIA recently received this video from a reader which shows a very simple but highly graphic extraction attempt with a sample of this “oily ash” cannabis
The sludge shown at the end of the process is of unknown composition, but we suspect it’s a form of clay spray used to bulk up the weight, which is probably the reason for most if not all contamination. Of course, no consideration is given by those adulterating the cannabis as to the health risks of what they are doing, but worse, it’s impossible to make any prediction because we have no idea how widespread any particular example of adulteration is.
What we can say however is that this contamination issue is in addition to the concerns over mental health and high THC content. There are, of course, millions of cannabis users out there (60% of the population if the study sample is to be believed) and the most vulnerable – the young, the mentally ill – are at the greatest risk of exploitation by this uncontrolled and unregulated illegal trade.
Anyone who is seriously concerned about the health risks posed by cannabis would be outraged at these “unintended” – but quite predictable – effects of prohibition, it’s what happens when you gift a massively profitable industry to uncontrollable organised crime.
A point very well made.
… infact, I wish I found this website sooner. It is very informative and well presented. Thank you.
I think your point above rather misrepresents the NHS choices website. By your logic someone could write about your site and accuse it of quoting the daily mail. The article goes on to challenge easy assumptions and critically analyses the research.
Well, to be honest I didn’t read that Daily Mail quote as being critical of the claim made by that paper at all and having re-read it I still don’t.
As for the critical analysis provided in the NHS article, it doesn’t really go that much further than the original paper does other than in mentioning the alcohol issue, which is such a glaring omission it couldn’t be ignored. It’s strange however that the issue of tobacco wasn’t also highlighted, especially given it’s prevalence in people with psychotic illness and its connection with cannabis use.
Also the NHS article states “This study is also large for its kind”, which is an odd way of saying the sample size was small.
I think one important point is missing: The only thing the study claimed to measure, it didn’t.
There was no measurements done to verify the potency and the composition of the cannabis used by the subjects, so there is know way to know, whether the cases actually smoked “skunk” with a high THC/CBD ratio. They might have been just smoking oregano for all we know.
I’m actually very suprised that the study didn’t get turned down by the reviewers just for using a yellow press term skunk.
The point I was making is that saying the NHS is ‘quoting the daily mail’ as if it is basing interventions on it seems unfair as the site in question is there to interpret the errant, misrepresentative, scaremongering headlines of publications like the daily mail – in order to do this it needs to mention what they are saying.
Antii Laine – Yes you’re right, the assumption about the THC/CBD content of so-called “skunk” is just that, an assumption. The claim is based on the Home Office study of a year or so ago which looked at the nature of the cannabis supplied by the illegal trade. It was, however, hardly a scientifically valid survey being based on police seizures which in no way can be considered a valid sampling method. In truth, we really don’t know what people are smoking.
Niall – if that was the intention of the NHS article it was very badly written and simply does not come across the way you imply. There is nothing in that article remotely critical of the Mail quote.
Good work Derek. A sensible and balanced critique.
I’d like to congratulate you on one of the best marijuana blogs around. You seem to be fully tuned into the same mental frequency as I am. I completely agree with everything you say. Your balanced reasoning skills are outstanding.
The truth is, that the belief that marijuana causes psychosis or serious harm is itself basically a delusional belief.
I have known many hundreds of long term smokers, I have never seen one have psychotic episode, and it strongly goes against my intuition (and interpretation of the scientific evidence) that marijuana causes any form of serious mental disorder. The only problem it might aggravate is anxiety disorders, then again I used to have severe problems with panic attacks, and I do not have any problems with marijuana (occasional anxiety, but that’s when I am blatantly reckless and consume excessive amounts- especially by ingestion).
I am totally sick and tired of marijuana being illegal- it is completely not justified and damn it I want to be able to smoke it without “breaking the law”. I want to be able to meet other stoner friends down at a marijuana cafe. But hell I’ll settle for medical marijuana so long as I can get prescribed it (I honestly think marijuana has a positive effect on my mental health, despite having serious former problems with depression and anxiety and having been hospitalized numerous times).