Comment – High-potency cannabis and the risk of psychosis study.

The long expected research from The Institute of Psychiatry in London regarding cannabis and psychosis has finally been published and has received the to be expected coverage in the press.

Before discussing the study it is important, regrettably, to distance UKCIA from a comment quoted in the BBC’s coverage from the Legalise Cannabis Alliance (LCA)

A spokesman from The Legalise Cannabis Alliance UK said: “We don’t need to worry about the health harms of people smoking cannabis per se, whether it is skunk or not.

“What is a concern is that as a result of prohibition some dealers put other stuff into the cannabis they sell that may be damaging. I’ve heard of lead and glass being put in it.”

UKCIA certainly does not agree with this. This site has always taken a sober interest in the mental health debate and has never simply tried to dismiss it.

If it is true as some claim that cannabis has become a more dangerous substance over the past few years we need to highlight the fact, identify the reasons it has happened and suggest ways to prevent it. Indeed the issue of cannabis and mental health, far from being of no concern, is one of the strongest arguments for law reform.

The LCA statement was trying to draw attention to another serious issue with illegal cannabis, that of contamination and they are not wrong to want to do that, but to dismiss this issue in the way they were quoted as doing is little short of crass.

It’s only partially reassuring to read on the LCA forum a post from Alun who writes

I seem to remember writing “we ought not to worry … ”

I don’t think I would have written “We don’t need to worry” because I believe we do, but to a far lesser extent than about contamination

That is still not a view UKCIA can endorse, both issues need highlighting because both are serious but the issue of contamination wasn’t the one being covered. Perhaps Alun should proof read his comments to the press a little more carefully and be in an alert frame of mind when writing them in future.

Anyway, to the study.

Published in The British Journal of Psychiatry, it’s yet another bit of research which has attracted the headlines, but which we are not allowed to see without paying. However, the abstract is here

Background

People who use cannabis have an increased risk of psychosis, an effect attributed to the active ingredient {Delta}9-tetrahydrocannabinol ({Delta}9-THC). There has recently been concern over an increase in the concentration of {Delta}9-THC in the cannabis available in many countries.

This doesn’t get off to a good start because that claim is not universally accepted and there is plenty of research around to demonstrate there has been no increase in the rates of psychosis nor any change in the family profile of mentally ill people  despite the huge rise in cannabis use over the past 50 or so years.

Anyway, the effect of cannabis which people seem to enjoy mimics psychosis, at least to an extent and THC is the main active ingredient in cannabis which causes the psychotic like effects which people seek.

The aim of the study is interesting:

Aims

To investigate whether people with a first episode of psychosis were particularly likely to use high-potency cannabis.

Note the wording of that – it seems to leave open the possibility that the psychosis is the reason these people use the high potency varieties. The study is looking for a correlation between the use of so-called “skunk” and psychosis, it isn’t looking for proof of a causal role. Now, to an extent this would seem a bit like fishing in a  bucket because people with mental health problems are well known for being problem drug users, they often drink heavily, smoke heavily and so on. When problem users take drugs they often seek out the stronger forms.

Method

We collected information on cannabis use from 280 cases presenting with a first episode of psychosis to the South London & Maudsley National Health Service (NHS) Foundation Trust, and from 174 healthy controls recruited from the local population.

Now the full paper probably goes into some depth to highlight the problems of selecting a control group would present, this isn’t mentioned in the abstract. However 280 cases and a control of 174 is a pretty small sample from which to draw any firm conclusions.

We will have to assume for now that the background of the control group were comparable with the ill people and that there were no other confounding issues. Again, the paper may cover that.

The results are interesting in ways which were not picked up by much if any of the media reports:

Results

There was no significant difference between cases and controls in whether they had ever taken cannabis,

So that would imply that as far as cannabis use goes, it’s no more common in people with mental illness than in the general population – health warning over sample size not withstanding.

or age at first use.

That is the interesting one. The claims have always been that early use of cannabis is likely to lead to an increase risk of getting psychosis, this would seem to go against that claim. Now, again we point to the small sample size and wouldn’t be so daft as to claim this study proves children are not at an elevated risk form using cannabis but that would seem to be what the study has found. The fact that this particular result was not picked up by the media is hardly a surprise

However, those in the cases group were more likely to be current daily users (OR = 6.4) and to have smoked cannabis for more than 5 years (OR = 2.1). Among those who used cannabis, 78% of the cases group used high-potency cannabis (sinsemilla, ‘skunk’) compared with 37% of the control group (OR 6.8).

Well, yes. People with mental illness use a lot of drugs and seem to seek oblivion more than people who aren’t ill.

Conclusions

The finding that people with a first episode of psychosis had smoked higher-potency cannabis, for longer and with greater frequency, than a healthy control group is consistent with the hypothesis that {Delta}9-THC is the active ingredient increasing risk of psychosis. This has important public health implications, given the increased availability and use of high-potency cannabis.

It’s also consistent with the theory that mentally ill people – or those developing an illness – self-medicate with cannabis and use drugs heavily, such heavy drug use being a pre-morbid indication of the emerging illness. The public health implications are surely that cannabis is not the controlled substance it should be.

It’s interesting to dig a little into these claims about the type of cannabis people use. On the streets of South London, as anywhere else the quality of the cannabis sold is highly variable. To obtain consistently good supplies you either have to grow it yourself or pay  a premium and know a good dealer. Yet according to the researchers quoted in the Guardian

80% of the cannabis sold on the streets of south-east London was now skunk.

So it is a bit of a mystery what the healthy cannabis users are smoking. In truth most people are probably smoking something less than the premium grade. It may be hydroponically grown weed, but it’s more than likely been shaken or quickly grown and quite badly produced – not to mention bulked out with various additives.

Prohibition has been very effective at disrupting the cannabis trade and it is almost impossible to make any statement about the nature of the product most people are using.

The BBC quoted Dr DI FOrte, one of the authors as saying

Unlike skunk, hashish – cannabis resin – contains substantial quantities of another chemical called cannabidiol or CBD and research suggests this can act as an antidote to the THC, counteracting its psychotic side effects.

This is one issue which is being misreported badly. It’s really important to understand that all cannabis plants can make hashish and that the resulting hash will have the same profile of THC/CBD as the plant it came from. Hash made form high THC plants will therefore be high THC hash. The “traditional” hash we used to get from North Africa was made from low potency cannabis plants (which is why the product was the more concentrated hashish and not weed).  It was the eradication of the North African supplies which created the demand for so-called “skunk” in the first place. High THC hash is available – although again at a premium.

However, the important point to make is that if these concerns are true this is all a very strong argument for properly controlling and regulating the commercial supply of cannabis so that people know what they’re buying and can make informed choices. If it is thought that some forms of cannabis really are dangerous, then these extreme forms could be properly restricted. Whilst we have prohibition, non of this is possible and the situation will never improve.

However, to put it all in proportion the authors are quoted in the BBC

… they point out that drug use only accounts for the minority of cases of psychotic illnesses – somewhere between 10% and 15%. Other risk factors, such as family history of mental health problems, play a far bigger part.

But they say cannabis, and particularly stronger skunk, should be considered a potential health hazard in a similar way to alcohol.

The pity is their work has been used by the prohibition campaign to re-enforce the very policy which has created the problem in the first place and which prevent just the sort of informed debate – or indeed the controls – the authors would like to see. If it really is so important that cannabis consumers use the traditional hashish products, perhaps it would be a good idea to allow them to buy it?

It doesn’t help when cannabis campaigners make ill-thought out press comments either.