Older Adults Hospitalized for Cannabis Use Faced Higher Dementia Risk
Ontario adults over 45 who had emergency or hospital visits for cannabis use were 1.72 times more likely to receive a dementia diagnosis within 5 years compared to the general population, though their risk was lower than for alcohol-related visits.
Quick Facts
What This Study Found
Individuals aged 45+ with acute care due to cannabis use had a 5.0% rate of dementia diagnosis within 5 years, compared to 3.6% for all-cause acute care and 1.3% in the general population. After adjustment, cannabis-related acute care was associated with 1.23x higher dementia risk than all-cause acute care and 1.72x higher than the general population, but 0.69x lower than alcohol-related acute care.
Key Numbers
6,086,794 individuals studied; 16,275 with incident cannabis-related acute care; 5.0% dementia rate in cannabis group vs 1.3% general population; aHR 1.72 vs general population; aHR 0.69 vs alcohol; cannabis acute care among 65+ increased 26.7-fold (0.65 to 16.99 per 100,000) from 2008 to 2021.
How They Did This
Population-based retrospective matched cohort study using Ontario health administrative data from 2008-2021 (follow-up to 2022), including 6.1 million individuals aged 45-105, comparing dementia diagnoses between those with incident cannabis-related acute care and matched controls using cause-specific adjusted hazard models.
Why This Research Matters
Cannabis use among older adults has surged dramatically, and this is one of the first large-scale studies to examine whether severe cannabis use is associated with dementia risk. The 26.7-fold increase in cannabis-related acute care among those 65+ between 2008 and 2021 underscores the scale of this emerging issue.
The Bigger Picture
This study adds dementia to the list of serious health outcomes associated with severe cannabis use in older adults. The dramatic rise in cannabis-related emergency visits among seniors reflects a population increasingly using cannabis without full awareness of potential risks, particularly regarding cognitive decline.
What This Study Doesn't Tell Us
Only captures cannabis use severe enough for emergency or hospital care, not regular or recreational use. Cannot establish causation. People presenting with cannabis-related acute care may have other risk factors for dementia. Cannabis use could be an early manifestation of cognitive decline rather than a cause.
Questions This Raises
- ?Is the association driven by direct neurotoxic effects of cannabis, or is cannabis use a marker for other dementia risk factors?
- ?Does the type or frequency of cannabis use matter?
- ?Would results differ for medical versus recreational cannabis users?
Trust & Context
- Key Stat:
- Cannabis-related ER visits among adults 65+ surged 26.7-fold from 2008 to 2021
- Evidence Grade:
- Strong: Large population-based cohort (6.1 million) published in JAMA Neurology with validated dementia algorithm and comprehensive adjustment for confounders.
- Study Age:
- Published in 2025 with data from 2008-2022.
- Original Title:
- Risk of Dementia in Individuals With Emergency Department Visits or Hospitalizations Due to Cannabis.
- Published In:
- JAMA neurology, 82(6), 570-579 (2025)
- Authors:
- Myran, Daniel T(16), Pugliese, Michael(13), Harrison, Lyndsay D(4), Stall, Nathan M, Webber, Colleen
- Database ID:
- RTHC-07220
Evidence Hierarchy
Looks back at existing records to find patterns.
What do these levels mean? →Frequently Asked Questions
Does cannabis use cause dementia?
This study found an association between severe cannabis use (requiring emergency care) and higher dementia risk, but it cannot prove causation. It is possible that early cognitive decline leads to cannabis use rather than the reverse, or that shared risk factors explain the link.
How does cannabis compare to alcohol for dementia risk?
In this study, cannabis-related acute care was associated with lower dementia risk than alcohol-related acute care (aHR 0.69), suggesting alcohol remains a stronger risk factor for dementia among substances requiring emergency intervention.
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Cite This Study
https://rethinkthc.com/research/RTHC-07220APA
Myran, Daniel T; Pugliese, Michael; Harrison, Lyndsay D; Stall, Nathan M; Webber, Colleen. (2025). Risk of Dementia in Individuals With Emergency Department Visits or Hospitalizations Due to Cannabis.. JAMA neurology, 82(6), 570-579. https://doi.org/10.1001/jamaneurol.2025.0530
MLA
Myran, Daniel T, et al. "Risk of Dementia in Individuals With Emergency Department Visits or Hospitalizations Due to Cannabis.." JAMA neurology, 2025. https://doi.org/10.1001/jamaneurol.2025.0530
RethinkTHC
RethinkTHC Research Database. "Risk of Dementia in Individuals With Emergency Department Vi..." RTHC-07220. Retrieved from https://rethinkthc.com/research/myran-2025-risk-of-dementia-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.