Cannabis use before first psychiatric hospitalization rose from 17% to 26% in Ontario over a decade
Among 81,809 first-time psychiatric inpatients in Ontario from 2007-2017, cannabis use within 30 days of admission increased from 16.7% to 25.9%, with the largest increases in personality disorders and psychotic disorders.
Quick Facts
What This Study Found
Cannabis use within 30 days of first psychiatric admission rose from 16.7% in 2007 to 25.9% in 2017. Cannabis use disorders increased from 3.8% to 6.0%. In 2017, 47.9% of patients aged 18-24 and 39.2% aged 25-34 used cannabis before admission. The largest diagnostic-group increases were in personality disorders (15% increase), schizophrenia/psychotic disorders (14%), and substance use disorders (14%).
Key Numbers
81,809 first admissions; 20.1% used cannabis overall; 16.7% in 2007 to 25.9% in 2017; CUD 3.8% to 6.0%; 47.9% of 18-24 year olds in 2017; AUC 0.88 for schizophrenia-gender interaction model
How They Did This
Retrospective cross-sectional analysis of 81,809 first-time admissions to non-forensic inpatient psychiatric beds in Ontario from 2007-2017 using the Ontario Mental Health Reporting System. Trends and characteristics were analyzed across years and diagnostic categories.
Why This Research Matters
This decade-long population-level trend data from an entire province establishes a clear baseline showing rising cannabis use among psychiatric inpatients. As a pre-legalization baseline (Canada legalized in 2018), it enables future assessment of whether legalization accelerated these trends.
The Bigger Picture
Nearly half of young adult first-time psychiatric inpatients used cannabis before admission by 2017. Whether cannabis contributes to psychiatric crises or people in psychiatric distress are more likely to use cannabis remains a critical unanswered question.
What This Study Doesn't Tell Us
Cannot determine whether cannabis use contributed to psychiatric admission or was incidental. Self-reported use may undercount actual use. Ontario-specific data. No post-legalization comparison.
Questions This Raises
- ?Did legalization in 2018 accelerate these trends?
- ?Is the increase driven by higher-potency products?
- ?Would screening and brief intervention for cannabis use in psychiatric settings improve outcomes?
- ?How does concurrent cannabis use affect treatment response?
Trust & Context
- Key Stat:
- 47.9% of 18-24 year old psychiatric inpatients used cannabis within 30 days of admission
- Evidence Grade:
- Province-wide administrative data covering over 81,000 first admissions across a decade, though administrative data cannot establish causation.
- Study Age:
- Published in 2021 using data from 2007-2017.
- Original Title:
- How High? Trends in Cannabis Use Prior to First Admission to Inpatient Psychiatry in Ontario, Canada, between 2007 and 2017.
- Published In:
- Canadian journal of psychiatry. Revue canadienne de psychiatrie, 66(12), 1059-1068 (2021)
- Authors:
- McGuckin, Taylor, Ferro, Mark A(2), Hammond, David(36), Stewart, Shannon, Maloney-Hall, Bridget, Madi, Nawaf, Porath, Amy, Perlman, Christopher M
- Database ID:
- RTHC-03337
Evidence Hierarchy
Looks back at existing records to find patterns.
What do these levels mean? →Frequently Asked Questions
Is cannabis causing more psychiatric hospitalizations?
This study cannot answer that. It found cannabis use before psychiatric admission is increasing, but whether cannabis contributed to the crisis or was coincidental to it cannot be determined from this data.
Which psychiatric diagnoses saw the biggest increase in cannabis use?
Personality disorders (15% increase), schizophrenia and other psychotic disorders (14%), and substance use disorders (14%) showed the largest increases in cannabis use before admission between 2007 and 2017.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-03337APA
McGuckin, Taylor; Ferro, Mark A; Hammond, David; Stewart, Shannon; Maloney-Hall, Bridget; Madi, Nawaf; Porath, Amy; Perlman, Christopher M. (2021). How High? Trends in Cannabis Use Prior to First Admission to Inpatient Psychiatry in Ontario, Canada, between 2007 and 2017.. Canadian journal of psychiatry. Revue canadienne de psychiatrie, 66(12), 1059-1068. https://doi.org/10.1177/0706743720984679
MLA
McGuckin, Taylor, et al. "How High? Trends in Cannabis Use Prior to First Admission to Inpatient Psychiatry in Ontario, Canada, between 2007 and 2017.." Canadian journal of psychiatry. Revue canadienne de psychiatrie, 2021. https://doi.org/10.1177/0706743720984679
RethinkTHC
RethinkTHC Research Database. "How High? Trends in Cannabis Use Prior to First Admission to..." RTHC-03337. Retrieved from https://rethinkthc.com/research/mcguckin-2021-how-high-trends-in
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.