Personal health and genetics featured prominently in a recent panel discussion on Marijuana: Is Canada Ready? held recently in Halifax. The public event, which drew more than 500 people, was offered in partnership with Genome Atlantic and Dalhousie University’s Schulich School of Law, Faculty of Management, and Faculty of Arts and Social Sciences.
Genome Atlantic invited to the panel Dr. Eileen Denovan-Wright and Dr. Melanie Kelly, two Dalhousie pharmacologists involved in pioneering cannabis research since the 1990s. Denovan-Wright’s research explores the potential of cannabinoids for treating Huntington’s disease and other neurodegenerative disorders, while Kelly studies endocannabinoid receptors located in the brain and other tissues, and the development of cannabinoids as medicines.
“Much of the discussion around the coming legalization of recreational cannabis in Canada is focused on public health, public safety and distribution models,” says Genome Atlantic’s Kristin Tweel. “Personal health is an important consideration too, including the genetic factors that could help predict who might benefit and who’s at risk from cannabis use, the promise of personalized medicine, and why more research is needed into the medical uses of cannabis. These are perspectives that Drs. Denovan-Wright and Kelly bring to the table.”
Denovan-Wright and Kelly rounded out an impressive panel of experts that included the Honourable Anne McLellan, Chancellor of Dalhousie University and Chair of Canada’s Task Force on Cannabis Legalization and Regulation; The Honourable Darrell Dexter, former Nova Scotia Premier the Vice-Chair of Global Public Affairs; Dr. Sylvain Charlebois, Dean of Dalhousie’s Faculty of Management; and Dr. Archie Kaiser, Schulich School of Law and Department of Psychiatry. Dr. Camille Cameron, Dean of the Schulich School of Law, moderated the discussion.
Genes matter
Denovan-Wright focused on the potential health risks of using cannabis. “There is a growing body of evidence – and it’s one of the most active areas of active cannabis research – that some people are vulnerable to developing severe mental illness when they use cannabis.” These mental illnesses include psychotic disorders, schizophrenia, bipolar depression and major depression. “That’s not to say that the drug is bad unto itself, but that individuals differ,” she said.
Denovan-Wright believes that genomics will play a vital role in helping predict which patients could benefit most from cannabis use and which are most at risk. “With sufficient research, genomics could be used to detect, forewarn and counsel those people predisposed to experiencing marijuana’s harmful effects. This will enable each of us to make good, informed decisions about how we use the drug.”
She expressed hope that after marijuana’s legalization, cannabis research would focus less on harm reduction and more on prevention, where genomics could play a significant role in changing behaviours and avoiding harm for those most at risk of experiencing the drug’s adverse effects.
She added that “genomics also plays a big role in breeding marijuana plants for certain properties, and in helping us to harness those qualities as we go forward into production.” Cannabis produced today contains more of the principal psychoactive ingredient, THC or tetrohydrocannabinol than it did in the 1960s, she noted.
Cannabis is a complex plant that produces many hundreds of chemical compounds including cannabinoids. They have distinct structures and act on a network of specific receptors in the central and peripheral nervous systems and the brain called the endogenous cannabinoid system. This system responds to plant cannabinoids and compounds naturally produced by the body. The endogenous cannabinoid system is implicated in controlling human memory, emotion, cognition, motivation and motor coordination.
“We have to face the fact that cannabinoids are somewhat unique drugs,” said Denovan-Wright. They can accumulate in bodies. The brain can also change in response to chronic exposure to these drugs. High dose of high potency drugs that are consumed over long periods of time can change the way our brains respond and alter this very important endogenous cannabinoid system required for proper brain function.” Age, sex, and ethnicity, she said, have also been shown to be factors that play roles in individual responses to the drug.
She added that while many of the more than 100 compounds produced by the cannabis plant have different properties, they could contain untapped medical potential for beneficial effects, while also creating a risk for additional harmful effects. “With legalized recreational use, not everyone is going to be negatively affected by cannabis if it’s used responsibly and we understand that dose, frequency of use and duration of use all matter.”
For Denovan-Wright, the bottom line is that “more research is needed and we also need to see ourselves as individuals with different genetic risks.”
The case for a separate medical stream for cannabis
Melanie Kelly, who specializes in translational pharmacology and novel drug development, made a case for retaining a separate federal regime for medical cannabis after the drug is legalized for recreational use next year. The recent federal Task Force on Cannabis Legalization and Regulation recommended that the medical regime continue, subject to a review after five years.
“A separate medical cannabis stream would help patients preserve their access to medical cannabis, including particular varietals, when the post legalization demand is expected to outstrip supply,” Kelly noted. She emphasized that a dual stream approach would help protect the supply of certain strains of medical cannabis that have desirable effects on patients, such as those strains with lower THC and higher cannabidiol (CBD), or specific combinations of other non-cannabinoid constituents that may contribute to beneficial therapeutic effects.
Retaining a medical stream would also drive clinical research into the therapeutic effects on cannabis, Kelly said. “It is vital to delineate the cannabis medical market in order to encourage pharmaceutical companies to develop drug identification number (DIN) products that meet Health Canada and Food and Drug Act requirements as therapeutics.”
Kelly added that a separate medical stream is also important to keep cannabis’ therapeutic use on the radars of medical and health professionals. “If there was one stream only, it would likely be driven by the consumer market and lean more towards the recreational use.”
Cannabis for therapeutic use is currently administered under the federal Access to Cannabis for Medical Purposes Regulation because it is not an approved drug in Canada. (A prescription drug needs to have a drug identification number assigned by Health Canada for coverage – and medical cannabis doesn’t have one.) At this time, it can only be recommended by a physician and obtained through a licensed producer. Purchase for recommended medical use is not currently covered by health insurance. Furthermore, many if not most, doctors are reluctant to recommend cannabis usage because their knowledge of the drug is limited.
Kelly said that while there is more substantial evidence that cannabis can be effective in treating chronic pain, chemotherapy-induced nausea and MS symptoms, clinical evidence is limited or inconclusive on its efficacy for many other conditions such as mood disorders involving anxiety and sleep disturbances, for post-traumatic stress syndrome and for inflammatory diseases of the gastrointestinal tract such as inflammatory bowel disease. “We lack good, clinical evidence for cannabis’ use to treat a host of conditions, and a great deal more research is needed,” adding that she feared “a single-stream approach could hinder this necessary research.”
Underlying Kelly’s preference for a dual-stream system is a firm belief that cannabis must be considered a medical drug like any other. “There shouldn’t be a stigma attached to using medical cannabis. Health care providers should have access to the latest research and therapies and patients should be able to benefit.”
