Now that cannabis has been legalized for recreational use in Canada, there's a growing need for research exploring the mental health implications of increased access to cannabis. That's the focus of the September Special Issue of the Canadian Journal of Addiction, official publication of the Canadian Society of Addiction Medicine. The journal is published in the Lippincott portfolio by Wolters Kluwer.

In October 2018, cannabis was legalized for recreational use by adults in Canada, spurring a demand for research to inform policy and healthcare practice related to cannabis use. Mental health professionals and addictions researchers are particularly interested in understanding the factors that contribute to cannabis use and misuse.

Titled 'Current Perspectives on Cannabis in Mental Health,' the Special Issue includes nine new research papers and commentaries related to cannabis legalization and its effects on mental health. A key focus is the impact of legalized cannabis in vulnerable subgroups, including adolescents and young adults and people with symptoms affecting mental health.

Karen Rowa, PhD, of McMaster University and colleagues evaluated cannabis use in nearly 800 patients seeking treatment for anxiety and related disorders. Forty-three percent of patients said they used cannabis four or more times per week. Of these, 22% had unhealthy cannabis use (such as frequent use or interference with daily activities) on a screening questionnaire.

The study also found increased indicators of psychological distress among patients seeking treatment for anxiety. "Legalization may contribute to the normalization of cannabis use as a method to cope with distress, which could further increase rates of use in this population," Dr. Rowa and coauthors write.

Isabella Romano, BSc, of University of Waterloo and colleagues analyzed factors associated with cannabis use in nearly 37,000 Canadian high school students. "One in four students reported past-year cannabis use," the researchers write. Cannabis use by minors remains illegal in Canada.

The study identified factors associated with cannabis use, including use of other substances, depressive symptoms, poor psychosocial and emotional functioning, higher screen time, and less sleep. The authors suggest school-based programs focusing on protective factors such as emotional resilience and mental health.

Two research papers focus on cannabis use among university students, one of which links cannabis use to higher anxiety scores—especially in females. An experimental study reports an innovative animal model of cannabis vaping to assess the effects of cannabis on brain activity: a type of research that is difficult to perform in humans.

The Special Issue also presents expert perspectives, including a critique of the Canadian government's approach to legalization. One commentary argues that the public health approach to legalization proposed by the Canadian government "has not been sufficiently adopted despite its many potential benefits." Another outlines priorities for a "comprehensive post-legalization cannabis research agenda," including measurement issues, potential risks and harms, therapeutic uses of cannabis, and policy related to legalization.

"The articles in this Special Issue reflect novel and high-quality research on the intersection between cannabis and mental health," Dr. Amlung concludes. "Broader dissemination of knowledge gained from research in these domains is critically important to increase the evidence base for clinicians, researchers, policy makers, community members, and other stakeholders to effectively respond to changes that occur in this exciting post-legalization era."