Cannabis and Mental Health – Priorities for research in Canada

This report is based on an environmental scan and scoping review by a University of Calgary research team that analyzed existing research into the relationships between cannabis use and mental health outcomes. It aims to guide the development of future research and policy development by drawing attention to knowledge gaps in the cannabis and mental health literature. While it highlights research on the potential risks and benefits of cannabis use, it is not meant to serve as an educational, public health or medical guide.

SEIZING THE OPPORTUNITY TO LEARN MORE ABOUT CANNABIS AND MENTAL HEALTH

The relationship between cannabis use and mental health has been the subject of a lot of research, especially over the last 15 years. Yet the links between the two are still not fully understood. With cannabis for non-medical use now legal in Canada, the need to identify and address the gaps in our knowledge has taken on new urgency.

To inform research agendas and policy development in Canada, the Mental Health Commission of Canada (MHCC) funded an environmental scan and scoping review of existing research into the relationships between cannabis use and mental health outcomes. The project revealed a number of gaps in the literature that represent valuable opportunities for future research.

The legalization of cannabis for non-medical use represents a big opportunity for Canada’s research community. As one of only two nations with legalized cannabis (along with Uruguay), researchers in Canada can tackle questions that would be difficult for other jurisdictions. With proper funding and a multidisciplinary approach, the country can be a world leader in research on the links between cannabis use and mental health outcomes.

The environmental scan and scoping review that this summary report is based on took a systematic approach to synthesizing existing research to identify where greater focus is needed. The project included 1,047 studies across a spectrum of research disciplines, including animal preclinical science, human preclinical science, and community and population health science.

From that assessment, there is a clear need for:

• more high-quality, fit-for-purpose study designs (i.e., ideal for answering the research questions under examination)
• clarity on the complex relationship between cannabis use and mental health
• insight into how the different ways of consuming cannabis affect mental health outcomes
• insight into the experiences of specific populations with regard to cannabis use and mental health outcomes.

Overall, what’s needed most can be summed up in a single word: specificity. Future research must be grounded in an understanding of the complex context of cannabis use, which can include existing mental health problems or illnesses, polysubstance use, factors unique to specific populations, and more. There is also a need to look more broadly at the effects of cannabis — to go beyond only studying its possible harms by considering potential benefits outside problematic use patterns. Nuanced approaches to study design and the interpretation of results will be critical in helping us better understand the relationships between cannabis use and mental health outcomes.