Older Adults Hospitalized for Cannabis Use Faced Higher Dementia Risk | Research

The takeaway

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.

Geriatricians and primary care physicians counseling older patients, researchers studying cannabis and cognitive decline, policymakers addressing senior cannabis use.

Cannabis-related ER visits among adults 65+ surged 26.7-fold from 2008 to 2021

What the researchers 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.

Why it 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 numbers in context

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 the study worked

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.

What this study cannot 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.

How to read the evidence

Strong: Large population-based cohort (6.1 million) published in JAMA Neurology with validated dementia algorithm and comprehensive adjustment for confounders.

When this study was published

Published in 2025 with data from 2008-2022.

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.

Questions still open

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?

Common 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.

Read the original research

Risk of Dementia in Individuals With Emergency Department Visits or Hospitalizations Due to Cannabis.

JAMA neurology, 82(6), 570-579

View on PubMed ↗Publisher’s paper ↗

Citation

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