By Pat Anson, PNN Editor

Medical marijuana is often touted as a treatment for chronic pain, but a new clinical trial found cannabis provided no significant improvement to people who took it for pain, anxiety or depression. Marijuana did help people sleep better, but it also raised their risk of cannabis use disorder (CUD).

“There have been many claims about the benefits of medical marijuana for treating pain, insomnia, anxiety and depression, without sound scientific evidence to support them,” says lead author Jodi Gilman, PhD, with the Center for Addiction Medicine at Massachusetts General Hospital (MGH). “We learned there can be negative consequences to using cannabis for medical purposes. People with pain, anxiety or depression symptoms failed to report any improvements, though those with insomnia experienced improved sleep.”

Gilman and her colleagues enrolled 186 people in the study and randomly assigned them to one of two groups. The first group was allowed to immediately obtain a medical marijuana card, while the second group had to wait 12 weeks before getting one. Both groups were allowed to choose their cannabis products at a dispensary, with no limits on the dose or frequency of use.

Participants in the immediate card acquisition group reported significantly more cannabis use in the study period, with nearly one in five (17%) developing CUD symptoms such as craving, tolerance and withdrawal within 12 weeks. The odds of having CUD were nearly 3 times higher in the immediate acquisition group than in the delayed acquisition group.

“This trial showed that CUD can develop at a fast rate within the first 12 weeks of medical marijuana card ownership, suggesting that those with a card may develop CUD at a similar rate as those who use cannabis recreationally and that the (medical) motive for use may not be protective,” researchers reported in in JAMA Network Open.

“Although most cases of CUD onset in the trial were mild, with 2 to 4 symptoms, these symptoms developed over a short, 12-week initial exposure. The most commonly reported CUD symptoms were higher tolerance and continued use despite the recurrent physical or psychological problems caused or exacerbated by cannabis.”

People with anxiety or depression -- the most common conditions for which medical cannabis is sought -- were at significantly higher risk of developing CUD than those with pain and insomnia.

Incidence of Cannabis Use Disorder

“Our study underscores the need for better decision-making about whether to begin to use cannabis for specific medical complaints, particularly mood and anxiety disorders,” said Gilman, who called for more regulation of medical marijuana.  “There needs to be better guidance to patients around a system that currently allows them to choose their own products, decide their own dosing, and often receive no professional follow-up care.”

Cannabis advocates say Gilman’s findings are at odds with larger observational studies (here, here and here) that found cannabis use disorder declined in states that legalized medical marijuana. They feel the study also lacked detail of CUD symptoms or what impact they had.

“Although the authors stress the notion that those in the card-holders groups were more likely to be diagnosed with symptoms of CUD, they never identify what these symptoms were, their severity, or how disruptive they were to these individuals daily lives and functioning — or even if in fact they were at all,” said Paul Armentano, Deputy Director of NORML, a marijuana advocacy group. 

“Finally, it should be recognized that virtually all therapeutic agents possess varying safety profiles. Medical cannabis is not innocuous. But its safety profile is far superior to that of many conventional pharmaceuticals for which it can provide an alternative, including opioids and benzodiazepines — even if one is to take these findings at face value.” 

A recent survey found that twice as many Americans are now using cannabis or cannabidiol (CBD) to manage chronic pain than opioid medication.