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December 2023

October 2023 marks the fifth anniversary of Canada’s controversial legislation on cannabis for non-therapeutic use. Indeed, with this decision in 2018, Canada became the second country in the world to legalize its sale, possession and use for non-medical purposes by adults (1). The main objectives of the Cannabis Act (C-45) were to: 1) restrict access to cannabis to a young population, 2) reduce cannabis-related crime and the surrounding illegal market, 3) ensure access to a safe product. Five years on, what is the overall impact of Bill C-45, and more importantly, what public health evidence has been accumulated on the subject?   In their retrospective study, Fischer, and Jutras-Aswad et al. 2023 reported that the overall social impact has been positive (2). In fact, there has been a significant reduction in arrests and prosecutions related to cannabis use, as well as in the social prejudice and other personal burdens associated with it (2). This reduction is more beneficial for marginalized and racialized populations, who were previously more affected by it (3, 4).   Nevertheless, the benefits directly related to the health of people who use cannabis in a non-therapeutic context are more scattered and less substantial. Recent data in the literature describe either an increase or a stabilization in the prevalence of cannabis use, cannabis-related emergency department visits, hospital admissions and driving under the influence of cannabis (2). These observations also include the younger population (15 to 25 years old) (5), highlighting that this legislative objective has not been met. In this way, robust longitudinal studies of this population are needed, as understanding their consumption trajectory could help to limit and prevent the associated risks and harm (6). It should be noted, however, that several studies have reported these effects during the COVID-19 pandemic, a period during which cannabis consumption may have increased due to stress and changes in daily habits (4).   Another important point concerning the health impact on recreational users concerns the THC content of cannabis products. Canada’s Lower-Risk Cannabis Use Guidelines (LRCUG) indicate that individuals who use cannabis should favor products with a lower total THC content or a higher CBD: THC ratio. The higher the total or relative THC content of the cannabis used, the greater the risk of acute or chronic adverse effects on mental or physical health. (7) However, more evidence is needed to support these recommendations.   In response to this knowledge gap in the literature, two studies on recreational cannabis will begin shortly in Dr Didier-Jutras Aswad’s laboratory. The first, SPECTRE, aims to assess the impact of inhaled cannabis-based products, which contain different proportions of active molecules, on acute psychoactive effects in healthy individuals who consume cannabis occasionally. The second study, TRICCHOME, aims to characterize the cannabis consumption trajectories of young adults (aged 18 to 24) who use cannabis regularly or daily via a mobile application. To follow the progress of these projects, stay tuned to our website and social networks!


  1. Ministère de la Justice, Legalization and regulation of cannabis [Online]; 07 Jul 2021 [cited 04 Dec 2023]. Available:
  2. Fischer, B., Jutras-Aswad, D., & Hall, W. (2023). Outcomes associated with nonmedical cannabis legalization policy in Canada: taking stock at the 5-year mark. CMAJ, 195(39), E1351-E1353. DOI: 10.1503/cmaj.230808.
  3. Le Devoir, Five years after legalization, legal cannabis dominates the market [Online]; 16 October 2023 [cited 04 December 2023]. Available:
  4. Statistics Canada, Five years after legalization, what have we learned about cannabis in Canada [Online]; October 16, 2023 [cited December 04, 2023]. Available:
  5. Health Canada, Progress report: Legalization and regulation of cannabis in Canada [Online]; 20 October 2022 [cited 04 December 2023]. Available:
  6. Kourgiantakis, T., Lee, E., Kosar, A.K.T., et al. Youth cannabis use in Canada post-legalization: service providers’ perceptions, practices, and recommendations. Subst Abuse Treat Prev Policy. 2023;18(1):36. DOI: 10.1186/s13011-023-00550-1
  7. Fischer, B., Robinson, T., Bullen, C., Curran, V., Jutras-Aswad, D., Medina-Mora, M. E., … & Hall, W. Lower-Risk Cannabis Use Guidelines (LRCUG) for reducing health harms from non-medical cannabis use: A comprehensive evidence and recommendations update. Int J Drug Policy. 2022;99:10338. DOI :

November 2023

One of the key issues talked about when it comes to cannabis is its effects on mental health. An estimated 26.2% of people with schizophrenia will have cannabis use disorder at some point in their lives, which is much higher than in the general public.(1) While some people with psychotic disorders say cannabis helps them to deal with their symptoms, unfortunately, studies show that using cannabis can make aspects of the disorder worse. For example, cannabis use has been linked to higher risks of treatment failure, hospitalisation, and reoccurrence of symptoms.(2)

A recent article by Argote et al. has looked at how the actual symptoms of schizophrenia spectrum disorders differ between those who use cannabis and those who don’t.(3) Their meta-analysis put together data from 21 different studies on the subject, producing interesting results. They found that, on average, people with schizophrenia spectrum disorders who used cannabis had more ‘positive’ symptoms, such as delusions and hallucinations, but also less ‘negative’ symptoms, such as such as lack of emotional expression, lack of speech and lack of motivation.

Meta-analyses like this aren’t able to conclude what might cause the findings, and so we can interpret these results in different ways. Is it possible that cannabis is affecting people’s brains, making some symptoms worse and others better? Are people with psychosis using cannabis as self-medication, to help with their negative symptoms? Or are people with psychosis who use cannabis fundamentally different in some way from those who don’t use cannabis – could some, perhaps, have not developed a psychotic disorder if they hadn’t used cannabis in the first place?

The authors of this paper consider all of these possibilities, but it will be up to future research to find the answers. In our lab, we have a number of different studies right now looking at how cannabis affects our minds, our behaviour and our health. One objective of our work is to find ways to reduce the risk of harm from cannabis use, especially in vulnerable populations such as people with psychotic disorders, using harm reduction and technology-based interventions.(4, 5) The more we learn about how cannabis links to psychosis, the better we can design ways to prevent the risk of harm, and the more we can empower people who chose to use cannabis to take control of their use and their health.


  1. Hunt GE, Large MM, Cleary M, Lai HMX, Saunders JB. Prevalence of comorbid substance use in schizophrenia spectrum disorders in community and clinical settings, 1990–2017: Systematic review and meta-analysis. Drug and Alcohol Dependence. 2018;191:234-58.
  2. Schoeler T, Kambeitz J, Behlke I, Murray RM, Bhattacharyya S. The effects of cannabis on memory function in users with and without a psychotic disorder: Findings from a combined meta-analysis. Psychological Medicine. 2016;46:177-88.
  3. Argote M, Sescousse G, Brunelin J, Baudin G, Schaub MP, Rabin R, et al. Association between cannabis use and symptom dimensions in schizophrenia spectrum disorders: an individual participant data meta-analysis on 3053 individuals. eClinicalMedicine. 2023;64:102199.
  4. Coronado-Montoya S, Tra C, Jutras-Aswad D. Harm reduction interventions as a potential solution to managing cannabis use in people with psychosis: A call for a paradigm shift. Int J Drug Policy. 2022;108:103814.
  5. Tatar O, Abdel-Baki A, Wittevrongel A, Lecomte T, Copeland J, Lachance-Touchette P, et al. Reducing Cannabis Use in Young Adults With Psychosis Using iCanChange, a Mobile Health App: Protocol for a Pilot Randomized Controlled Trial (ReCAP-iCC). JMIR Res Protoc. 2022;11(11):e40817.

September 2023

Heidar Sharafi, a postdoctoral trainee in our laboratory, recently published an article in the prestigious Addiction scientific journal in collaboration with Hamzah Bakouni, Christina Mcanulty, Sarah Drouin, Stephanie Coronado-Montoya and Arash Bahremand. This systematic review and meta-analysis focused on the use of prescription psychostimulants as a replacement therapy for amphetamine-type stimulant use disorder. By synthesizing the results of ten randomized controlled trials, this study concluded that prescription psychostimulants can significantly reduce craving in people with amphetamine-type stimulant use disorder. However, our results have shown that this type of treatment does not seem effective in reducing stimulant use, withdrawal symptoms as well as depressive symptoms. We were also able to identify that higher doses of prescription psychostimulants generally lead to a greater reduction in craving and stimulant use. The only treatments available for stimulant use disorders are psychotherapeutic and psychosocial interventions, which are insufficient in a large majority of cases. Our study results therefore highlight the importance of continuing research efforts in this area in order to find pharmacological treatments that would be effective for people with stimulant use disorder. In the laboratory of Didier Jutras-Aswad, we continue to contribute to the scientific knowledge with new meta-analyses, which will soon be published, relating to the effectiveness of naltrexone, bupropion and modafinil as pharmacotherapies for amphetamine-type stimulant use disorder. A pan-Canadian clinical trial of dexamfetamine with/without contingency management for the treatment of methamphetamine use disorder will also be running shortly.. For more information, visit the Available Studies section of our website. Click here to access Heidar’s article.  Click here to access the press release.

August 2023

Doctoral candidate in psychiatric sciences Ovidiu Tatar, along with a team of Canadian and international researchers, has recently published in a prestigious psychiatry journal the results of a study that evaluated preferences of young adults with psychosis for online psychological interventions for decreasing cannabis use. Cannabis dependence is up to 15 times higher in young adults with psychosis compared to the general population and reducing cannabis use in these individuals improves clinical outcomes. Evaluating preferences for online interventions facilitates engagement in treatment and increases intervention efficacy.

Individuals with first episode psychosis and cannabis dependence from three Canadian provinces participated to an electronic survey between January 2020 and July 2022. The authors used advanced methods to collect and analyse participant opinions related to online psychological interventions and found higher preference for moderate intervention intensity, for example sessions with a length of fifteen minutes sessions that are completed once a week.  Participants valued the autonomy conferred by online interventions as these can be completed both at the clinic and outside the clinic. Importantly, app-based interventions for decreasing cannabis use were perceived as complementary to in-person delivered interventions. Participants expressed high preferences for using smartphones and interventions that incorporate video elements and enable chat communication with clinicians.  

In a world where our relationship with technology is ever evolving, this study informed the development of a novel mobile intervention app (iCanChange), which is undergoing clinical testing and could help people with first episode psychosis reduce cannabis use and facilitate their recovery.

Article by Christina McAnulty


1. Tatar O, Abdel-Baki A, Dyachenko A, Bakouni H,
Bahremand A, Tibbo PG, et al. 
Evaluating preferences for online psychological
interventions to decrease cannabis use in young adults withpsychosis: An
observational study
. Psychiatry Res. 2023 May 30;326:115276.


June 2023

On April 19, 2023, Quebec media outlets announced that flavored vaping devices would be removed from sales (1). Designated by various names such as electronic cigarettes or “vapes”, these objects are hand-held devices that heat an inhalable solution containing nicotine, a humectant and synthetic volatile compounds (2). In fact, vape retailers would face a prohibition on distributing any vaping products that have flavors other than tobacco. Why has vaping consumption become a public health issue and what factors have led to this ban?

In Quebec, it is estimated that 20% of vapers are young people under the age of 18 (1). Vape’s growing popularity is partly the result of the marketing strategies involved in its sales. Data gathered in the U.S. and Canada suggest a significant increase in the use of nicotine vaping products in recent years, especially among young people (3). Its popularity could be attributable to the attractive designs of the devices, their packaging, and their appealing flavors, such as ‘’peach ice’’ and ‘’daiquiri’’(2). Another element potentially contributing to this trend is the societal perception of the health risks associated with vaping. That is, more than half of regular vape users consider it to be harmless (4). But are these devices as risk-free as one may believe?

Scientific literature suggests that vaping is associated with neurological, pulmonary, and mental health risks, in addition to containing carcinogenic metabolites (@). In 2019, a total of 39 deaths have been associated to vaping in the United States, which could be due, at least in part, to its high amount of vitamin E (2).  Vape devices also contain other hazardous metabolites that are known carcinogens as well as nicotine (4). Unfortunately, nicotine intake can have harmful impacts on neurocognitive functions, especially on youth as their brain is still developing. Vaping as a teenager also leads to an increased risk of smoking later in life (5). Lastly, many health risks associated to vaping remain unknown as its distribution and use are fairly recent (6). In the absence of evidence-based data on the safety of the product in different contexts and different populations, and in an attempt to reduce its use among young people, regulations have been issued.

Even though vaping is associated with increased risks of deleterious health consequences, could it be a safer alternative to smoking or assist in smoking cessation? Data shows that vaping increases tobacco consumption among minors (5). On the other hand, the data is not as conclusive when it comes to the adult population (6). It doesn’t seem impossible that vaping may aid in smoking reduction or cessation in specific therapeutic contexts. However, given the lack of data on vape’s efficacy in this context and its safety, individuals who live with nicotine dependence are encouraged to seek out other therapeutic modalities such as pharmacological treatments, nicotine replacement products as well as medical or psychosocial interventions (3, 7). Only further studies will determine whether vaping can become a new tool that may be included in strategies for smoking cessation.

Find more information here to get help on smoking cessation strategies.

Sabrina Bijou (she/her/elle)


  1. QMI A. Vapotage: Québec interdit les saveurs TVA Nouvelles; 2023 [Available from:
  2. Dinardo P, Rome ES. Vaping: The new wave of nicotine addiction. Cleveland Clinic Journal of Medicine. 2019;86(12):789-98.
  3. Hammond D, Reid JL, Burkhalter R, O’Connor RJ, Goniewicz ML, Wackowski OA, Thrasher JF, Hitchman SC. Trends in e-cigarette brands, devices and the nicotine profile of products used by youth in England, Canada and the USA: 2017-2019. Tob Control. 2023 Jan;32(1):19-29. doi: 10.1136/tobaccocontrol-2020-056371.
  4. Bernat D, Gasquet N, Wilson KO, Porter L, Choi K. Electronic Cigarette Harm and Benefit Perceptions and Use Among Youth. American Journal of Preventive Medicine. 2018;55(3):361-7.
  5. Levy DT, Warner KE, Cummings KM, Hammond D, Kuo C, Fong GT, et al. Examining the relationship of vaping to smoking initiation among US youth and young adults: a reality check. Tobacco Control. 2019;28(6):629-35.
  6. Wang RJ, Bhadriraju S, Glantz SA. E-Cigarette Use and Adult Cigarette Smoking Cessation: A Meta-Analysis. American Journal of Public Health. 2021;111(2):230-46.
  7. Soule EK, Plunk AD, Harrell PT, Hayes RB, Edwards KC. Longitudinal Analysis of Associations Between Reasons for Electronic Cigarette Use and Change in Smoking Status Among Adults in the Population Assessment of Tobacco and Health Study. Nicotine and Tobacco Research. 2020;22(5):663-71.

Cannabis Harm Reduction for Youth Living with Psychosis and Using Cannabis

Cannabis use can be more problematic for individuals who have experienced an episode of psychosis. Stephanie Coronado-Montoya, a PhD candidate in the Didier Jutras-Aswad laboratory, advocates for harm reduction as a means of helping people manage problematic cannabis use.

Through her review of over 11,400 scientific articles, Stephanie found that few cannabis-focused interventions existed for people with psychosis who wanted to reduce or prevent cannabis-related harms. Her national survey of patient preferences found two significant demands which emerged from the population: that interventions be short and technology-based.

The CHAMPS app responds to these demands (a mobile app containing a brief psychosocial intervention aiming to reduce cannabis-related harms in people with psychosis). To learn more about this initiative, please listen to the full episode and follow Stephanie on Instagram (@the.brain.diaries).


March 2023

Genetic Basis of Cannabis Use

Cannabis is one of the most widely used psychoactive substance worldwide. The increased risk of developing a cannabis use disorder has recently been associated with specific genetic variants. These findings have led to numerous studies focused on the characterization of the complex relationship between genetic background and cannabis use. In this context, the article entitled “Genetic basis of cannabis use: a systematic review” aims to summarize some of the current knowledge on the genetic determinants underlying cannabis use, identify genetic variants associated with increased risk of cannabis misuse and its related harms, and highlight the importance of further research to better understand the genetic susceptibilities associated with cannabis use.

One of the genes commonly identified among the results of genomic approaches is the CNR1 gene, which codes for the cannabinoid 1 receptor (CB1R). CB1R is highly expressed in the brain and it is the primary target of the euphoric compound found in cannabis, i.e., delta-9-tetrahydrocannabinol (THC). Studies have shown that certain variants of the CNR1 gene are associated with a greater inclination to consume cannabis, as well as increased sensitivity to the effects of THC. The same can be said about the AKT1 gene, which codes for a protein involved in the regulation of cell growth and survival. In addition, other genes that have been associated with cannabis use include the DRD2 gene, which codes for a dopamine receptor involved in reward and motivation, and the FAAH gene, which codes for an enzyme involved in the breakdown of cannabinoids in the body.

It is important to note that the genetic basis of cannabis use is complex, multifactorial and polygenic, and individual genetic variants probably have little effect on an individual’s propensity to consume. Interactions between specific genetic susceptibilities and environmental factors, such as peer pressure, product availability, and social norms, also play an important role in cannabis use and its related consequences. However, the study of genetic factors makes it possible to explain the mechanisms involved in the response to psychoactive substances, which in turn ensures the ability to identify susceptibility factors that could be used to prevent possible harm or optimize certain benefits. It is thus important to consider genetic factors in the response to different cannabis products, an effort that we are promoting in the laboratory by including different genomic approaches to experimental designs involving cannabinoid administration in humans. This approach will be implemented in our next projects that will start in the upcoming months. Stay tuned to our projects to learn more.


Hillmer A, Chawar C, Sanger S, D’Elia A, Butt M, Kapoor R, Kapczinski F, Thabane L, Samaan Z. Genetic basis of cannabis use: a systematic review. BMC Med Genomics. 2021 Aug 12;14(1):203. doi: 10.1186/s12920-021-01035-5. PMID: 34384432; PMCID: PMC8359088.