Medical marijuana: Does research back up claims of therapeutic benefits?

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A new Globe and Mail investigation is raising alarming questions about the safety of cannabis being sold illegally in unregulated dispensaries. But for the thousands of Canadians who use regulated and tested medical cannabis, there is another urgent issue researchers are scrambling to address: Does it work?

Background and regulations

Health Canada has not approved the use of medical cannabis, but a court ruling requires the government to "provide reasonable access to a legal source of marijuana when authorized by a health-care practitioner."

Producers must pass Health Canada's application and inspection process in order to sell medical marijuana. According to the department, there are currently 34 licensed producers in Canada. More than 53,000 clients were registered with licensed producers during the period between Jan. 1 and March 31, 2016.

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There are also an unknown number of Canadians who are allowed to grow their own medical marijuana at home as a result of a 2014 court decision. A ruling earlier this year struck down a ban on homegrown medical marijuana; the government is expected to bring in new rules by the end of the summer.

Doctors can decide if and when patients should qualify for medical marijuana. But this puts them in a difficult situation, as it has not been approved by the government to treat any medical condition.

Canadian Medical Association president Cindy Forbes said in a statement that the current regulatory environment is "a serious challenge for physicians in providing the best care to patients."

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Unanswered questions

There's no shortage of anecdotal evidence from individuals who claim cannabis lessens their pain, combats the symptoms of chemotherapy or reduces their anxiety. But there are no large high-quality scientific studies to back any of those statements.

"We need to see if, in fact, it's legitimate by the standards of medical science," said M-J Milloy, an assistant professor of medicine at the University of British Columbia.

The active ingredients of cannabis that are believed to have therapeutic effects are called cannabinoids. They include compounds such as tetrahydrocannabinol (THC) and cannabinol (CBN). Although the mechanisms aren't entirely clear, it's believed cannabinoids work by binding to receptors found in the body.

The major obstacle that has long stood in the way is the lack of funding along with the stigma associated with studying cannabis. Governments wouldn't allow researchers access to it, few funds were available for studies and most researchers didn't want their names tied to the drug. There are a number of cannabis producers who are also becoming involved in medical research, and some experts have warned about the potential conflict of interest this could pose.

Although things have started to change, there's still a long way to go, Dr. Milloy said.

So far, the research into medical cannabis has produced mixed results. In June, 2015, the Journal of the American Medical Association published an analysis of 80 studies looking at its efficacy.

Researchers found some evidence that cannabinoids can reduce chronic pain and the muscle contractions or involuntary movements suffered by many with multiple sclerosis. But there was little proof it helps reduce anxiety, nausea and other symptoms of chemotherapy or sleep disorders. Researchers also couldn't find evidence to show cannabis promotes weight gain in HIV patients.

The future

The research is still in its infancy. Experts believe that, as more work is done in this area, the true usefulness of medical cannabis will finally become clear.

Jason McDougall is one of the scientists hoping to answer some of those questions. The Dalhousie University professor and pain researcher is currently conducting a trial studying the effectiveness of cannabinoids for osteoarthritis pain. The study was funded by the Arthritis Society, an example of how patient groups are moving to embrace the potential medical uses of cannabis.

Like many other researchers in the field, Dr. McDougall isn't studying marijuana that's smoked, vaporized or eaten. He's looking at specific cannabis molecules isolated from the plant. Many researchers believe that, once the research is complete, cannabinoids will be made available in pill form.

What's needed now, experts say, is more research funding to clarify what medical cannabis can be used for and to provide doctors with much-needed guidance.

Dr. Forbes said in a statement that the Canadian Medical Association "calls on Health Canada and research agencies to fund the scientific research needed" to provide evidence for medical marijuana.

Dr. Milloy agrees, saying the work needs to be done in order to give patients the answers they deserve. "I think the time has passed where medical researchers can say this is all malarkey," he said. "It's not malarkey. There is something here. Our responsibility is to try and test it with all the rigour it demands."