Cannabis Use May Quadruple Dementia Risk, Study Finds

A newly published large-scale study has cast serious doubt on the long-term safety of cannabis.

Based on data from more than 6 million Canadians, the research shows that adults who had used cannabis and been hospitalized or visited an emergency room were up to four times more likely to develop dementia within five years, compared to non-users.

The findings have sparked concern among researchers and public health experts, especially given the sharp rise in cannabis-related hospital visits in recent years.

“The data is too compelling to ignore,” the study’s authors said, according to WebMD.

The study looked at individuals aged 45 and older, none of whom had a prior dementia diagnosis. It found that:

• 5% of cannabis users developed dementia within five years.
• This compares to just 1.3% among non-users.

Between 2008 and 2021, cannabis-related hospitalizations rose fivefold—and among those over 65, the increase was even more staggering: 27 times higher than in 2008.

Researchers were careful to stress that correlation does not equal causation. But the strength of the association and the enormous sample size suggest that the connection may be more than coincidental.

Who Was Included in the Study?

• 16,000 cannabis users were closely tracked for five years.
• The average age was 55.
• 60% were men.
• None had been diagnosed with dementia at the start.

Researchers believe that this demographic focus makes the results particularly relevant for middle-aged and older adults, who may not fully understand the cognitive risks associated with long-term cannabis use.

But the study doesn’t definitively prove that cannabis causes dementia.

Experts say the findings should lead to greater public awareness, especially among older adults and those with underlying health conditions.

We need more research to fully understand the connection,” one of the study’s lead researchers said, “but for now, the risk cannot be dismissed.