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King’s College London Launches New 6000-Person Cannabis Trial Aimed At ‘Informing Safe Prescribing’, But Questions Raised Over Impartiality

A MAJOR new study into the effects of cannabis use on mental health was launched by King’s College London last week, marking what is understood to be the largest independent study of its kind. 

With the UK government repeatedly citing a ‘lack of significant research… on the adverse effects’ of cannabis, the study’s researchers hope it could help provide the information needed for UK physicians to feel more confident in ‘prescribing cannabis safely’. 

The study has already proven controversial among many within the cannabis industry who have raised concerns around impartiality given the narrow purview of its lead researcher Dr Marta Di Forti’s previous research, which has largely focused on links between cannabis and psychosis. 

However, Dr Di Forti says a key aim of this study is to expand the understanding of cannabis users outside this ‘narrow minority’, and understand those who experience only positive effects, either medically or recreationally, from cannabis use. 

She told BusinessCann: “We wish to reach out to those out there using cannabis, in particular those benefiting from it. Without their help we will continue to have a polarised debate on cannabis, with us thinking it is all bad and should be banned, and others believing that because it is a plant it cannot have adverse effects.” 

The Study

The ‘Cannabis & Me’ (CAMe) Study aims to interview and monitor 6,000 participants between the ages of 18 and 45, who are already using cannabis regularly, have used it less than three times in their life, or never used it before. 

Last week the full study was launched, following a pilot phase that began in March, seeing recruitment for participants open to any English-speaking London residents with no history of psychotic illness and who are willing to take part. 

According to Dr Di Forti, the study was submitted to the Medical Research Council (MRC) for funding in 2019 and was granted £2.5m in 2020. 

“The pandemic has delayed the start to this date. The study involves several collaborations and labs, which were all affected by COVID 19. Finally, everyone is ready to start.”

CAMe is expected to run for five years, and the researchers plan to begin publishing the first set of results after the first year, meaning we can reportedly expect to see the initial findings in 2023 or early 2024, though Dr Di Forti says she expects ‘data from the biological data analysis will take longer’. 

Participants will initially need to complete an online questionnaire, which takes around 40 minutes, then a ‘sub-group of all the participants from both the current cannabis users and the never/only once or twice groups’ will be invited to complete a more in-depth face-to-face assessment to explore aspects such as previous trauma. 

A virtual reality experience will also be used to measure participants’ physiological response to certain circumstances. 

Dr Di Forti explained that the study will also establish the levels of ‘THC, CBD and metabolites’ in participants’ blood, alongside the levels of endocannabinoids including anandamide and 2AG, their DNA structure and ‘epigenetic profiling alongside their past experiences (trauma, adversities, etc.)’. 

“The main aim of the study is to understand why a minority of cannabis users experience psychological and cognitive adverse effects – this is the clinical population I care for as a clinician.

“If we can identify the environmental and biological factors that make a minority susceptible to adverse effects when using cannabis daily either for medicinal or recreational reasons, we can inform safe prescribing and side-effects monitoring (we use virtual reality to test if or how cannabis affects reality perception). 

“We can also offer more information to the general public, to avoid adverse effects when using cannabis and how to recognise them. Everyone in our society can recognise the negative effects of excessive alcohol consumption, but not everyone is familiar on how to identify the changes in thinking, processing and cognition that a minority experience when using cannabis.”

Impartiality Concerns

Dr Di Forti has published numerous studies focusing on ‘the causal link between cannabis use and psychotic disorders’ with King’s College over the past decade, many of which have been widely cited in the media and by politicians across the globe. 

One study, published in 2015, found that the ‘risk of individuals having a psychotic disorder showed a roughly three-times increase in users of skunk-like cannabis compared with those who never used cannabis’. 

Furthermore, it suggested that ‘the high potency of cannabis in South London might have resulted in a greater proportion of first-onset psychosis cases being attributed to cannabis use than in previous studies’. 

The focus of the study’s key findings, which were widely reported in the media and have been repeatedly cited by anti-cannabis advocates ever since, led a number of people within the cannabis industry to challenge its impartiality. 

Dr Di Forti has now directly addressed these accusations in a number of interviews, including a recently published article by Cannabis Health, in which she said the media and politicians often use her data in a ‘context which doesn’t necessarily represent my view, and this is what tends to upset me’. 

“People now associate me with the idea that nobody should use cannabis and that cannabis is a toxic substance, which is not what I think.”

Chairman of the Scottish Hemp Association Kyle Esplin argued in a LinkedIn post on the subject that the report and language used within it failed to emphasise data which found those who smoked hashish actually had a lower risk of psychosis than those who didn’t consume cannabis at all. 

Another 2019 study expanded on the previous study, finding that daily use of high potency cannabis is ‘strongly linked to the risk of developing psychosis’, and that if high potency cannabis were no longer available in Amsterdam, psychosis would be expected to drop from 37.9 to 18.8 per 100,000 people per year, and from 45.7 to 31.9 in London. 

In response, an article was published questioning the study’s assumption of causality in The Lancet Psychiatry, where the study was initially published. 

Its authors argued that their own findings and others ‘illustrate that cannabis use might be higher among individuals with a genetic liability that predisposes such individuals to cannabis use and the development of psychosis or psychotic disorders’.

Professor Mike Barnes, head of the Cannabis Industry Council and The Medical Cannabis Clinicians Society, told BusinessCann: “Dr Di Forti is an experienced and well-respected researcher. However, her work has focussed on the links between high-THC recreational use and psychosis. 

“I just hope that this study is not skewed to confirm her prior work. We must remember that properly prescribed cannabis for medicinal use carries virtually no risk of psychosis, as the patient will be appropriately screened and the medicine will contain CBD which counters the ‘high’ of THC. As long as this is made clear in any results and the study recruitment is not biased, then this is an interesting research trial.”

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