New Research Uncovers Shocking Link Between Cannabis and Dementia

Cannabis has been a hot-button topic for years. Some praise its health benefits, like pain and anxiety relief, while others still label it the devil’s lettuce. And while most stoners were busy celebrating 4/20, new research just dropped a bombshell: a potential link between cannabis use and dementia.

The cohort study, published in the journal JAMA Neurology, contained data from more than 6 million individuals aged 45 years or older with no history of dementia from 2008 to 2021. 

Researchers analyzed that data to identify new dementia diagnoses among individuals who had required emergency department visits or hospitalizations due to regular cannabis use. This group was compared to three others: the general population, people who had care visits for any reason, and individuals hospitalized for alcohol-related issues.

“Long-term and heavy cannabis use has been associated with memory problems in midlife along with changes in brain structure associated with dementia,” says Dr. Daniel Myran, co-author, Canada Research Chair in Social Accountability at the University of Ottawa, and Associate Scientist at The Ottawa Hospital. “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.” 

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Over the course of 13 years, 16,275 individuals 45 and older—60% of whom were male—required an emergency or hospital visit due to cannabis use. During the study period, first-time acute care visits for cannabis in this age group increased more than fivefold, rising from 6.9 to 37.6 per 100,000 people. 

“Regular cannabis use might directly increase the risk of dementia through changes in brain structure," co-author Dr. Colleen Webber said in a statement. "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. 

Among individuals with cannabis-related medical care, around 5% were diagnosed with dementia within five years, and 19% within ten. This diagnosis rate was notably higher than that of people who were treated for other health issues during the study period. Regardless of other social and health-related factors, those who have cannabis-related hospital stays still have an elevated risk of developing dementia. 

"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,” says Myran.