On his return to Canada from a tour in Afghanistan, the niggling doubt that Shanon Fenske had harbored had grown into a certainty. Something was wrong with him.

Plagued by nausea and headaches at the end of every workday, he had suspected the bomb-jamming device he carried on his back was making him sick. However, he didn't realize just how sick until he consulted with the medical professionals back home.

Doctors swiftly diagnosed him with testicular cancer, which Veterans Affairs Canada later admitted was caused by the equipment he had been using, and within days he was sent into surgery. A year later, the cancer returned, and in the fall of 2011 and he underwent chemotherapy.

Fenske struggled with intense side effects from the chemo: his hair went completely black, he developed blood clots, and struggled to swallow food or even pills. Prescribed medical cannabis despite having what he describes as a “pretty conservative” approach to drugs, he discovered it immediately assisted with much of his pain and digestive issues.

But he noticed it also had another, completely unanticipated effect.

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“The first time that I smoked the marijuana, I was so overwhelmed with emotion. I remember tears coming to my eyes, because I had forgotten what it felt like to feel happy. I had forgotten what it felt like to feel alive. It was like, all of a sudden, I just felt all of this human emotion that I had shut off,” Fenske says. “You come back from war, you don’t realize how different you are from what you were before.”

Later, Fenske’s symptoms of nightmares, emotional detachment, the resurfacing of violent scenes and deaths he had witnessed, depression, and suicidal thoughts were diagnosed as post-traumatic stress disorder — or PTSD.

“Almost anybody who has PTSD has huge problems in their marriages or close relationships because they’re just too distant,” he says. “When your other hard-charging buddies are dealing with the same thing and no one is talking about it, it just kind of (becomes) normalized,” he says.

According to Veterans Affairs Canada, as many as one in 10 war zone veterans will experience PTSD, and at a rate of 9.2 per cent, PTSD among the general population in Canada is one of the highest in the world.

Recently, researchers from the University of British Columbia faculty of medicine and the B.C. Centre on Substance Use analyzed data collected by Statistics Canada on more than 24,000 Canadians.

As Fenske described, many people with PTSD self-medicate or are prescribed cannabis to alleviate their symptoms. What the researchers discovered appears to back those experiences. In a study published on Nov. 5, 2019 in the Journal of Psychopharmacology, they found that people with PTSD who do not use cannabis were seven times more likely to have experienced a major depressive episode and were 4.7 times more likely to have thoughts of suicide, compared to people who neither use cannabis nor have PTSD.

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“Even though it was a hypothesis, oftentimes your hypothesis doesn’t end up being supported by the research. In this case it was a very strong distinction there between cannabis users and non-users, so I think that did surprise me quite a bit,” says Stephanie Lake, lead author of the study and PhD candidate at the UBC Faculty of Medicine’s School of Population and Public Health. “It definitely warrants further investigation into the potential effectiveness of cannabinoid-based therapies for treating PTSD.”

For doctors who have been treating the disorder with cannabis for years, this association comes as no surprise.

“More or less I just listened to a lot of my patients with PTSD, which includes my veteran patients,” says Dr. Michael Hart, a physician based in London, Ont., who has been treating PTSD patients with cannabis since 2014. “They said that they just weren’t getting adequate relief from a lot of the traditional pharmaceuticals that they were choosing, and they wanted something better. They wanted something that would provide them with more high-quality relief, and when they started using medical cannabis, they got that relief and they reported that back to me.”

There has never been a drug specifically made for the treatment of PTSD, says Hart, and as a result most treatment has centered around medications intended for addressing anxiety or depression. However, studies have shown that people suffering from PTSD have much lower levels of certain biomarkers. Biomarkers are the way in which the presence of a diseased or disordered state can be biologically measured.

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One of these is a neurotransmitter called anandamide, a fatty acid and endocannabinoid, which are the cannabis-like molecules naturally produced by the human body.

“It’s been shown that people with PTSD have 50 per cent lower levels of anandamide. By using cannabis, you can replace that deficiency,” says Hart. “As a physician and a clinician, you always get your best results when you treat someone clinically that has a deficiency. It doesn’t matter if it’s a vitamin or a hormone or whether it’s a cannabinoid, but if you can correct a deficiency you can get really good clinical results. I think that’s part of the reason why so many people with PTSD have done so well with medical cannabis.”

A randomized, controlled trial in using cannabis for PTSD — the first in Canada — is already underway at UBC’s Okanagan campus, headed by clinical psychologist Zach Walsh and cannabis producer Tilray.

“I think the clinical trials really help us hone in on the research questions in terms of the effectiveness of cannabinoid-based therapies: which specific therapies are more effective in different scenarios and how we can scale up these treatments to the broader population,” says Lake. “I think the results of this paper, in combination with those trial results, will help guide the work into the future to figure out where we go from here.”