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Experts question new study on cannabis use disorder in patients

A recent study, on the risk of CUD in medical cannabis patients, has left experts with more questions than answers.

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Experts question new study on cannabis use disorder in patients
Experts argue it's not possible to accurately diagnose CUD in medical cannabis patients with current tools.

Experts have responded to a new study which claims patients with a medical cannabis card are at increased risk of cannabis use disorder.

Medical cannabis experts have raised concerns about the recent study, which suggests US patients in possession of a medical cannabis card may be at risk of “rapid onset” cannabis use disorder (CUD). 

A randomised control trial, carried out by researchers at Massachusetts General Hospital in Boston, consisted of 269 people who used cannabis products to improve insomnia, pain, anxiety or depressive symptoms.

One group was allowed to obtain a medical cannabis card immediately, while the second group, designed to serve as a control, was asked to wait 12 weeks before obtaining a card.

The team reported that the odds of developing CUD were nearly twice as high in the cannabis card cohort than in the wait list control group. By week 12, 10 per cent of the group had developed a CUD diagnosis, according to the findings, with the number rising to 20 per cent in those seeking a card for anxiety or depression.

The paper concluded that owning a medical cannabis card led to the “rapid onset and increased incidence and severity of CUD in some participants.”

Additionally, it observed “no benefits of obtaining a medical marijuana card for pain, anxiety, or depressive symptoms.”

But experts and medical cannabis prescribers have responded – with more questions than answers, remaining around the study, which was funded by the National Institute on Drug Abuse.

Dr Peter Grinspoon, a leading cannabis expert and prescribing primary care physician based in Massachusetts, where the study took place, pointed out several issues with the trial.

Experts question new study on cannabis use disorder in patients

Dr Peter Grinspoon has 25 years of experience in medical cannabis

What difference would a medical cannabis card make?

As recreational cannabis is legal in the state of Massachusetts, those who had the card would have the same access to cannabis as those who didn’t – the only difference would be cost, according to a response from Dr Grinspoon.

The model used in the study also “assumed a constant effect of a medical marijuana card over time” with visits at two, four and 12 weeks.

But Dr Grinspoon highlights that it is unusual for a pain patient to have titrated up to a therapeutic dose within just two weeks, particularly without guidance from a doctor.

How are the researchers defining tolerance?

The paper reports the “most common” CUD symptoms as “higher tolerance” and “continued use despite the recurrent physical or psychological problems caused or exacerbated by cannabis”.

But Dr Grinspoon questioned how the researchers were defining “tolerance”.

“How would they develop a tolerance that quickly? The whole thing makes no sense for medical cannabis patients, because you are supposed to titrate up to effect, so of course you are using more… that isn’t tolerance,” he writes.

How do we accurately diagnose CUD in medical cannabis patients?

Perhaps most importantly, the paper focuses on the symptoms of CUD – some of which developed in as little as two weeks – but this is framed as addiction, which takes at least 12 months to develop, Dr Grinspoon says.

Virtually all of the CUD identified in the study is ‘mild’, based on just two to three symptoms, and he suggests that if you took tolerance out of the equation, there would likely be little CUD found in either group.

Dr Grinspoon’s point is backed up by a paper published in 2021, in which Dr Staci Gruber and colleagues argue that it is not possible to accurately diagnose CUD in medical patients with the tools currently available.

After 54 medical cannabis patients completed the Cannabis Use Disorder Identification Test – Revised (CUDIT-R), the authors concluded: “Analyses revealed that the CUDIT-R does not appear to be an appropriate tool for identifying CUD in MC patients.

“Screening tools specifically designed to assess CUD in MC patients are needed and should distinguish between frequent use and problematic use.”

Dr Grinspoon also pointed out the fluctuation in the number of cases of CUD between the weeks, raising concerns about the accuracy of the diagnosis.

The number of cases of CUD dropped in the control group between weeks two and four and the cases are defined as having a CUD diagnosis “during at least one time point’. 

He added: “I don’t think you develop CUD within two weeks, which seven of the people in the first group did. Addictions don’t develop and aren’t diagnosed that way. 

“What’s worse, it doesn’t look like it was the same people who qualified for CUD, it says ‘18 participants (17.1 per cent) in the immediate card acquisition group had a CUD diagnosis during at least one time point’. 

“Why did the number of CUD cases drop in the control group? If they aren’t the same cases how accurate could the diagnosis possibly be? The number of cases would grow, not fluctuate if it were an accurate diagnosis in medical patients.”

Anti-cannabis?

Professor Mike Barnes, chair of the UK Medical Cannabis Clinicians Society, agreed that it was unlikely CUD could be diagnosed within the short time frame.

There is no way that CUD can be sensibly diagnosed in 12 weeks – 12 months is more realistic,” he said.

He went on to question the finding that there was “no benefit for pain, anxiety, or depressive symptoms.”

“We do not know the criteria for the issuing of the card. Are they suggesting that cannabis is of no use for pain, anxiety and depression? If they are, that flies in the face of international research and pragmatic global usage,” Prof Barnes continued.

“Is the funder [National Institute on Drug Abuse] of any relevance here?”

He added: “This is a sad paper that seems to be anti-cannabis and the authors need to think about the negative effect that this work has on the lives of many people who may benefit from proper and sensible cannabis use for long term conditions.”

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Sarah Sinclair is a respected cannabis journalist writing on subjects related to science, medicine, research, health and wellness. She is managing editor of Cannabis Health, the UK’s leading title covering medical cannabis and CBD, and sister titles, Cannabis Wealth and Psychedelic Health. Sarah has an NCTJ journalism qualification and an MA in Journalism from the University of Sunderland. Sarah has over six years experience working on newspapers, magazines and digital-first titles, the last two of which have been in the cannabis sector. She has also completed training through the Medical Cannabis Clinicians Society securing a certificate in Medical Cannabis Explained. She is a member of PLEA’s (Patient-Led Engagement for Access) advisory board, has hosted several webinars on cannabis and women's health and has moderated at industry events such as Cannabis Europa. Sarah Sinclair is the editor of Cannabis Health. Got a story? Email sarah@handwmedia.co.uk / Follow us on Twitter: @CannabisHNews / Instagram: @cannabishealthmag

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