Canadian Doctors Warn Medical Cannabis Is Overhyped

More and more people, young and old, are fast becoming fans of legalised weed. That popularity has been greatly aided by the proliferation of laws that allow it to be used as a medical treatment, not just in Australia, but in other countries such as Canada, which legalised medical cannabis in 2001. But Canadian doctors, much like their US neighbours to the south, are less enthused than the general public about the bold promises of medical pot.

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Today, a panel of 18 experts published new simplified guidelines for when the average doctor should prescribe cannabis in the journal Canadian Family Physician. Their short answer: Not very often, and not for most of the conditions it's been advertised to treat.

The panel reviewed studies and clinical trials that evaluated using medical cannabis to treat everything from headaches to depression. Despite the deep well of research, they overall found that most studies were too small, imprecise and otherwise flawed to base any solid recommendations on. For many conditions, there aren't even any randomised, placebo-controlled trials - the sort of studies agencies such as the US Food and Drug Administration rely on when deciding to approve a drug - to consider as evidence.

"In general we're talking about one study, and often very poorly done," said Mike Allan, the lead author of the guideline, community physician, and professor of family medicine at the University of Alberta, in a statement. "For example, there are no studies for the treatment of depression. For anxiety, there is one study of 24 patients with social anxiety in which half received a single dose of cannabis derivative and scored their anxiety doing a simulated presentation."

"This is hardly adequate to determine if lifelong treatment of conditions like general anxiety disorders is reasonable," Allen added.

According to the authors, the short list of conditions that likely seem to be helped by weed include certain forms of chronic nerve pain; muscle spasms caused by multiple sclerosis or spinal cord injuries; vomiting and nausea brought on by cancer treatment; and pain from otherwise terminal illnesses. But even there, the benefits were usually modest at best, and harder still to see with smoked medical weed.

"Medical cannabinoids should normally only be considered in the small handful of conditions with adequate evidence and only after a patient has tried a number of standard therapies," Allan said. "Given the inconsistent nature of medical marijuana dosing and possible risks of smoking, we also recommend that pharmaceutical cannabinoids be tried first before smoked medical marijuana."

The panel's recommendations are far from unusual among the medical profession. Organisations such as the American Medical Association and American Society of Addiction Medicine have long noted the lack of good research surrounding the use of medical cannabis, even as they tentatively support doctors and patients having access to it in states where it's permitted.

Of course, that lack of good research is in no small part due to the fact that governments continue to officially classify pot as an irredeemably dangerous substance with no medicinal benefits at all. It's this very reticence that led advocates to push for a patchwork, state-by-state approach to legalisation in the US - a model that's proven to be incredibly fragile to the whims of those in power, such as US Attorney General Sessions. And while the legalisation movement has made it easier for scientists to study pot more recently, they still run into many bureaucratic hurdles.

That theoretically shouldn't be a problem for Canada in the near future. Last November, the country passed a law allowing for the wholesale legalisation of marijuana. But there continue to be questions about how and when the rollout will actually be implemented (not that these delays have stopped dispensaries from starting to illegally offer marijuana to customers, though).

At the end of the day, Allen and his colleagues know no one on either side will be happy with their advice. But the best way forward, they say, is doing the homework.

"Better research is definitely needed - randomised control trials that follow a large number of patients for longer periods of time. If we had that, it could change how we approach this issue and help guide our recommendations," he said.

The new guidelines are expected to be given to some 30,000 clinicians across Canada.

[Canadian Family Physician]

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