A new study published in JAMA Neurology has revealed that individuals who visit the emergency department (ED) or are hospitalized due to cannabis use are at a significantly higher risk of developing dementia within five years. The findings suggest a 23% and 72% greater risk for dementia diagnoses for individuals with cannabis-related ED visits and hospitalizations, respectively, compared to those with acute care for other reasons or the general population.
Understanding the Link Between Cannabis and Dementia
Long-term, heavy cannabis use has been associated with memory issues in midlife and changes in brain structure that are linked to dementia. However, until now, there was limited research estimating the risk of dementia in individuals whose cannabis use led to emergency or hospitalization care. Dr. Daniel Myran, a key author of the study, explains, “We set out to estimate the risk of being diagnosed with dementia in a group of people whose cannabis use resulted in a visit to the emergency room or required a hospitalization for treatment.”
Study Design and Methodology
The study analyzed health data from over 6 million adults aged 45 and older in Ontario, Canada, who had no history of dementia when they entered the cohort between 2008 and 2021. These individuals were followed until 2022 to examine any new diagnoses of dementia after they sought acute care for cannabis use. The study compared this group to three others:
Individuals with an all-cause acute care visit.
The general population.
Individuals with acute care due to alcohol use.
Key Findings
The study revealed several significant trends and correlations:
Over the study period, 16,275 individuals (0.3%) aged 45 years or older sought acute care due to cannabis use, with 60% of them being male.
The annual rate of cannabis-related acute care visits increased significantly, rising more than five-fold from 353 visits in 2008 to 2,508 visits in 2021, with the largest increase among those aged 65 and older (26.7-fold).
Among individuals aged 45 and older who received acute care for cannabis use, 5% were diagnosed with dementia within five years, and 19% were diagnosed within ten years. In comparison, individuals with acute care for other reasons had a 3.6% dementia diagnosis rate within five years and 14.8% within ten years. The general population had even lower rates of dementia diagnoses—1.3% at five years and 5.5% at ten years.
After adjusting for various social, mental health, and chronic condition factors, individuals with acute cannabis-related care were found to have a 1.23-fold and 1.72-fold higher risk of dementia compared to those with all-cause acute care and the general population, respectively.
While cannabis use was linked to a higher risk of dementia compared to the general population and those with all-cause acute care visits, the risk was moderately lower than that associated with alcohol-related acute care. This suggests that while cannabis use is linked to an increased risk of dementia, alcohol use might pose an even higher risk in individuals requiring acute care.
The authors emphasized two key cautions in interpreting the study’s results:
The study only examined individuals whose cannabis use led to acute healthcare visits and did not consider those with less severe cannabis use that did not require medical intervention.
The study only identifies an association between cannabis use and dementia risk and does not establish causation.
The study authors discuss potential mechanisms that might explain how cannabis use could increase the risk of dementia. Dr. Colleen Webber, co-author of the study, notes that regular cannabis use could directly contribute to dementia through changes in brain structure. Additionally, cannabis use may exacerbate other known dementia risk factors, such as high blood pressure, head trauma, depression, and social isolation.
While more research is needed to fully understand the impact of cannabis on cognition and dementia, the study highlights a crucial link that should be considered in discussions between patients and healthcare providers. As cannabis use continues to rise, particularly among older adults, these findings may inform future public health initiatives and clinical approaches to managing the risks associated with cannabis use.
Dr. Myran concludes, “While we collectively need more research to better understand potential risks of regular cannabis use on cognition and dementia, we hope these findings can inform discussion between patients and healthcare providers.”
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