Behind a Smokescreen: Is Canada Ready for Cannabis Legalization?

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By: Meital Yerushalmi and Chantel Kowalchuk

A recent article in the Spring issue of the IMS Magazine highlighted concerns surrounding cannabis legalization with respect to its impact on driving while high, as well as on the challenges associated with the enforcement of impaired driving. As cannabis use and legalization continue to be politicized and featured in the media, our focus turns to the objectives, health impact, and the potential research outcomes from legalization. Here we employ a scientific approach to dispel common misconceptions.

Recent news of the federal government’s pledge to legalize cannabis (marijuana) by July 2018 has rekindled the globally growing and contentious debate regarding the legalization of cannabis for recreational use.1 Following marijuana legalization in nine American states, Canada will soon legalize the recreational use of marijuana, fulfilling Prime Minister Justin Trudeau’s 2015 campaign promise. While the legislation of Bill 45, the Cannabis Act,2 is currently underway, the debate surrounding this controversial issue is far from over.

Currently, the use of marijuana is permitted in Canada for medical purposes only. Users of medical marijuana can purchase quality-controlled cannabis from producers licensed by Health Canada. They are also permitted to produce a limited amount of cannabis for their own medical purposes, or designate someone to produce it for them.3 In contrast, possessing and selling cannabis for non-medical purposes is illegal under the Controlled Drug and Substances Act.4 However, the new legislation will remove marijuana consumption and incidental possession from the Criminal Code, arguing, broadly, that the current ban on cannabis does not effectively limit use and distribution.5 As a result, recreational use for those over the age of 18 will become legal. The objectives of the Cannabis Act are to deter criminal activity by imposing serious criminal penalties for those operating outside the law, to prevent young persons from accessing cannabis, to establish strict product safety for public protection, and to reduce the burden on the criminal justice system in relation to cannabis.2 Notwithstanding the importance of these objectives and considering the young age proposed for its legal use, a discussion of the impact of cannabis on health is warranted.

Most Canadians support the legalization of cannabis for recreational use, albeit with apprehension over the young age proposed by the legislation. Considering the popularity of cannabis among youth combined with the fact that the brain continues to develop into a person’s mid-20s, the use of cannabis by young adults raises concerns over its neurological impacts on the developing brain. Studies suggest that in young adults, frequent, long-term use may lead to deficits in cognitive function, including memory, concentration, intelligence, and decision-making lasting into adulthood.6,7 Changes in brain structure, particularly in regions responsible for reward response, have also been shown in young users when compared to nonusers.8 Cannabis use by people in their late teens is also linked to an increased risk for early-onset psychosis, particularly in those with preexisting vulnerability and users of high doses.9 Yet, the literature on cannabis risks in youth is not at a consensus, with some studies finding no long-term adverse effects. This discrepancy is likely due to study design, as, given their ethical complexity, studies on youth consumption of cannabis tend to be observational in nature and are therefore unable to control for confounding variables. Nevertheless, research on the impact of cannabis on youth is essential in the face of legalization. In Colorado, youth past-month marijuana use increased by 20 percent in the two‐year average (2013/2014) since the legalization of recreational marijuana, compared to the two‐year average prior to legalization (2011/2012).10 Given the current popularity of cannabis among Canadian youth, it is imperative that we understand its health impacts in this age group in the face of the upcoming legislation.

In addition to its neural effects on youth and adults, cannabis also impacts the respiratory system as it is commonly consumed via inhalation through the lungs. Regular cannabis smokers report more symptoms of chronic bronchitis (wheezing, sputum production, and chronic coughing) than non-smokers, and long-term use can lead to airway inflammation, and lung hyperinflation.11 Additionally, cannabis users experience more respiratory infections, as the immunological competence of their respiratory system is impaired. While public health efforts that are against cigarette smoking show success in decreasing smoking rates in recent decades, cannabis smoke contains many of the same carcinogens as tobacco smoke, with some in higher concentrations. However, echoing the trend in other research fields pertaining to cannabis and health, the long-term effect of cannabis on the respiratory system are not fully understood. Despite the evidence on the impact of cannabis smoking on the respiratory system, no association was found between chronic cannabis smoking and an increased risk of emphysema, and studies show inconclusive results with respect to its association with respiratory cancers.12

Similarly, evidence linking cannabis use and cardiovascular health demonstrate that cannabis increases heart rate in a dose-dependent manner, raising concern about adults with cardiovascular disease.13 In fact, laboratory studies indicate that smoking cannabis provokes angina in patients with heart disease, and suggests that cannabis can increase the risk for myocardial infarctions.12

Lastly, cannabis use has been linked to the development of psychiatric disorders. For example, cannabis has been associated with an increased risk for schizophrenia that increases with frequency of use in a dose-response manner in youth, and persisted after controlling for the effects of possible confounders. Nevertheless, other studies have been inconclusive and show no clear evidence of this association. Similarly, risk of psychotic disorders was higher in regular users than in non-users, though the association was attenuated after adjustment for potential confounders, rendering the common causal hypothesis difficult to exclude. Finally, non-consistent and weak associations have been reported between cannabis use and depression, as a dose-response relationship between frequency of use in youth and depressive disorder was shown. However, the association did persist after adjusting for confounders, leading the investigators to argue that confounders were not controlled for to exclude the possibility that depressed youth are more likely to use cannabis.12

Evidently, studies on the health impacts of cannabis often lack statistical rigor and are therefore inconclusive, perhaps stemming from the complex nature of cannabis use and the high likelihood of confounders. Additionally, stigmatization and poor funding toward cannabis research compound the difficulty of studying the drug’s effects on one’s health. With the new legislation, cannabis will become more accessible for research purposes and may become less stigmatized by the public and funding agencies, which may lead to more research into the neurobiology of cannabis and the health impacts of its recreational use among the different age groups. Legalization may also drive further research into its use as a therapeutic agent, allowing studies to expand from focusing primarily on substance abuse and physiological risks and into further, thorough investigation of its possible benefits. Overall, from a research standpoint, legalization of cannabis will allow development of the necessary knowledge required to inform the public health and policy decisions going forward.

It seems as if this multifaceted, controversial issue will continue to make headlines and stir speculation surrounding the outcomes of legalization to personal health and public safety. Truth be told, it is difficult to predict whether legalization of cannabis in Canada will fare similarly to the US. Regardless, talk of legalization has brought focus upon the effects of cannabis, usage in youth, regulation, and research barriers, encouraging a discussion which, at the very least, promotes necessary public knowledge and education.



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