Cannabis Consumption Associated with Elevated Risk of Anxiety Disorders

Examining health data from over 12 million Ontarians, the study discovered that individuals seeking emergency treatment due to cannabis use faced nearly a fourfold rise in the likelihood of receiving a diagnosis of an anxiety disorder within three years, compared to the broader population. Moreover, the research sheds light on the possibility of cannabis exacerbating pre-existing anxiety symptoms.

These results emphasize the intricate relationship between cannabis consumption and mental well-being, challenging the perception of cannabis as a harmless substance and emphasizing the necessity for caution in its medicinal or recreational application.

1. Individuals requiring emergency care for cannabis use showed a 3.9-fold increased risk of developing new anxiety disorders compared to the general population.
2. The study also found a 3.7-fold increased risk of severe or worsening anxiety disorders following cannabis-related emergency department visits.
3. This extensive research suggests a potential causal relationship between cannabis use and increased anxiety, advocating against its use as a treatment for anxiety symptoms.

Conducted by a team of researchers from the Bruyère Research Institute, University of Ottawa Department of Family Medicine, The Ottawa Hospital, and ICES, this study stands as the largest investigation into the correlation between cannabis consumption and anxiety to date.

Published today in The Lancet’s eClinical Medicine, the study encompassed a cohort of over 12 million individuals residing in Ontario, Canada, from 2008 to 2019, who had never been diagnosed with or treated for anxiety.

Utilizing health records from ICES, the researchers analyzed the risk of developing an anxiety disorder among individuals who had sought emergency department (ED) care due to cannabis use, comparing it to the risk among the general population.

• Risk of a new anxiety disorder: Within three years, 27.5 percent of individuals who had an ED visit for cannabis use were diagnosed with a new anxiety disorder in an outpatient, ED or hospital setting compared to 5.6 percent of the general population—a 3.9 fold increased risk after accounting for social factors and other mental health diagnoses.
• Risk of severe or worsening anxiety disorders: Within three years, 12.3 percent of individuals who had an ED visit for cannabis use had a hospitalization or an emergency department visit for an anxiety disorder compared to 1.2 percent of the general population—a 3.7 fold increased risk after accounting for social factors and other mental health diagnoses.
• In individuals with an ED visit where cannabis was the main reason for a visit, the risk of having a hospitalization or ED visit for an anxiety disorder increased by 9.4 fold compared to the general population.
• Men and women and individuals of all ages with an ED visit for cannabis use were at elevated risk of developing new anxiety disorders relative to the general population. Importantly, younger adults (10-24 years) and men were at particularly elevated risk.

The ongoing discourse revolves around whether cannabis use contributes to the development of anxiety disorders or if individuals are using cannabis as a form of self-medication for existing anxiety symptoms.

The latest study, the largest of its kind, suggests that cannabis use could exacerbate anxiety.

Irrespective of the causative factors, the authors advise against using cannabis to alleviate anxiety symptoms due to the lack of supporting evidence for its efficacy, the possibility that it may impede the pursuit of other evidence-backed treatments, and the potential risk of exacerbating anxiety symptoms significantly.

“Cannabis use has rapidly increased in Canada over the past 15 years and there is a general sense that cannabis is relatively harmless or has health benefits. Our study cautions that in some individuals, heavy cannabis use may increase their risk of developing anxiety disorders,” says Dr. Myran who is a Canada Research Chair in Social Accountability at the University of Ottawa, an ICES Adjunct Scientist, an Investigator at the Bruyère Research Institute, and a Clinician Investigator at The Ottawa Hospital.