Cannabis-Related ER Visits Linked to Higher Dementia Risk, Study Finds

Adults who end up in the hospital because of cannabis use could be rolling the dice with their brain health, according to new research out of Canada. The Institute for Clinical Evaluative Sciences (ICES) has found that those with an emergency visit tied to cannabis face a 23% higher risk of being diagnosed with dementia within five years. For people who were actually hospitalized, the risk rockets to 72%.

Published in JAMA Neurology, the study analyzed health records from more than six million Ontarians aged 45 to 105, spanning from 2008 to 2021. Of these, 16,275 had some form of acute care due to cannabis use—most of them men.

The numbers are pretty stark. Annual rates of cannabis-related ER visits shot up fivefold for folks between 45 and 64, and a jaw-dropping 27 times for those over 65. The researchers noted that even after adjusting for things like pre-existing health conditions, socioeconomic status, and prior care for other substances or mental health issues, the link between cannabis-related acute care and dementia risk stuck around.

Dr. Daniel Myran, who led the study, said that this doesn’t prove cannabis causes dementia, but it definitely highlights a concerning association. He was also “very surprised” by the sharp rise in older adults showing up in ERs or hospitals because of cannabis—from 353 in 2008 to 2,508 in 2021. And for those over 65, the increase was even steeper.

Among people who had these cannabis-related trips to the hospital, 5% were diagnosed with dementia within five years, and that number jumped to 19% at ten years. Those are the kind of numbers that should make anyone think twice before lighting up too often—especially as the years tick by.

The study does come with some caveats. Researchers didn’t have detailed information on how frequently or in what ways people were using cannabis, or other lifestyle factors like smoking tobacco. Plus, the findings only apply to people whose cannabis use was severe enough to land them in acute care, not casual users.

With cannabis now legal for medical and recreational use in many places, Dr. Myran cautioned that legality does not mean harmlessness. Regular use or higher-strength products may carry real risks, particularly for brain health and memory. It’s another reminder that, much like alcohol, moderation and awareness go a long way.