Seeking emergency care for marijuana linked to ‘increased risk’ of dementia: Study

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People who have sought emergency medical care for marijuana are more likely to develop dementia within five years of seeking attention, a new study found.

The comprehensive study of more than 6 million people was published April 14 in the journal JAMA Neurology.

Researchers out of Ottawa and Toronto found that 23% of individuals who had “incident acute care” due to cannabis use had a “23% increased risk of a new dementia diagnosis within five years” compared to those with an emergency room visit or hospital for any other reason.

“They have a 72% greater risk compared to the general population,” Dr. Daniel Myran, a Canada research chair in social accountability at the University of Ottawa, told CNN.

“Long-term and heavy cannabis use has been associated with memory problems in midlife along with changes in brain structure associated with dementia,” Myran detailed in a press release.

“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.”

The study included 6 million adults — aged 45 years or older — from Ontario who had no history of dementia when they entered the study between 2008 and 2021, and were followed until 2022.

Myran noted to the outlet: “Within five years of an emergency room visit or hospitalization for cannabis, 5% of people were diagnosed with dementia, and within 10 years, 19% of people were diagnosed with dementia.”

He added: “While this study was done in Canada, it should apply to all of North America, including the U.S.,” noting a May 2024 study that shows daily or near daily use of marijuana surpassed alcohol by 2022.

The increased risk could be caused by the way cannabis works in the brain, Dr. Colleen Webber, co-author and Bruyere Health Research Institute scientist, said in the press release.

“Regular cannabis use might directly increase the risk of dementia through changes in brain structure,” Webber said.

“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.”

But Myran told CNN that more research is needed.

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“This is not a study that anyone should look at and say, ‘Jury’s in, and cannabis use causes dementia,’” Myran stressed.

“This is a study that brings up a concerning association that fits within a growing body of research,” added Myran, who noted that “there’s certainly a pathway where there’s potential inflammation and microvascular damage from marijuana.”

Myron said it could be that regular cannabis use causes people to develop other risk factors for dementia, such as depression, social isolation and lower educational attainment.

It’s also possible that people who regularly use cannabis are more likely to have major trauma to the brain caused by such things as car crashes, he added.

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