WASHINGTON (dpa-AFX) - While cannabis enthusiasts marked 420 Day with celebrations, a new study in JAMA Neurology has cast a shadow over the festivities, revealing a potential link between regular cannabis use and a heightened risk of dementia.
The study analyzed health records of more than six million Canadians between 2008 and 2021. Participants were aged 45 to 105 and did not have dementia at the start of the study.
Researchers found that individuals who had visited an emergency room or were hospitalized for cannabis-related issues faced a notable increase in dementia diagnoses over time. Within five years of such a visit, 5 percent were diagnosed with dementia, which later surged to 19 percent within ten years.
'Someone who has an emergency room visit or hospitalization due to cannabis has a 23 percent increased risk of dementia within five years compared to someone who was at the hospital for another reason. They have a 72 percent greater risk compared to the general population,' study co-author Dr. Daniel Myran, an assistant professor in the department of family medicine at the University of Ottawa in Canada, told CNN.
One of the study's co-authors also pointed to broader trends in marijuana use. Citing a May 2024 report, they noted that daily or near-daily cannabis use had overtaken alcohol consumption by 2022.
'Regular cannabis use might directly increase the risk of dementia through changes in brain structure,' co-author Dr. Colleen Webber explained. 'It's also possible that regular cannabis use increases the risk of other established risk factors for dementia, including high blood pressure, head trauma and other injuries, and a higher risk for depression and social isolation.'
The data revealed a striking rise in cannabis-related emergency visits among older adults. Between 2008 and 2021, the rate of ER visits due to marijuana increased fivefold among those aged 45-64 and nearly 27-fold for people aged 65 and older.
These findings add to the growing body of evidence prompting further scrutiny of cannabis use, especially as its social acceptance and legal access continue to expand.
However, Myran noted that, 'This is not a study that anyone should look at and say, 'Jury's in, and cannabis use causes dementia.'
He told CNN, 'This is a study that brings up a concerning association that fits within a growing body of research.'
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