April 30, 2025, 12:45 pm | Read time: 3 minutes

For years, cannabis consumption has been a part of everyday life for some people, typically in the form of dried female flowers, which have an intoxicating effect due to their THC content. However, a recent study raises questions about the long-term health effects: It suggests that cannabis use might be linked to an increased risk of a dementia diagnosis.

Study Examines Link Between Dementia and Cannabis

A recent study investigated whether heavy cannabis use might be associated with an increased risk of a later dementia diagnosis. Researchers looked at cases between 2008 and 2021 where cannabis use was so severe that emergency room visits or hospital stays were necessary. The analysis was based on health data from more than six million adults aged 45 and older in Ontario, who had no dementia diagnosis at the start of the study.¹

Overall, the scientists identified 16,275 people who were admitted to the emergency room due to cannabis-related issues. This group was then compared to three other groups: people who needed emergency treatment for other reasons, the general population, and individuals who received medical care for alcohol abuse.

Study Results

Those who required acute medical help due to their cannabis use had a significantly higher risk of developing dementia in the following years. Five years after the incident, five percent of this group received a dementia diagnosis, compared to 3.6 percent of people with other emergency causes and 1.3 percent in the general population.

Overall, the risk of a dementia diagnosis in cannabis-related emergencies was 72 percent higher than in the general population and 23 percent higher than in other medical emergencies. Although the risk was lower compared to people treated for alcohol, it remained notably elevated.

Interpretation of Results

The study only examined severe cannabis use, not occasional use. While a link between cannabis use and a dementia diagnosis was found, causality could not be established. Additionally, it is unclear how the affected individuals consumed cannabis.

Despite some limitations, the study suggests that hospitalization due to cannabis use could be a potential risk factor for later dementia. Although no direct link was proven, the results indicate that further research is needed.

Further Study Results on the Effects of Cannabis

The current study supports a 2012 investigation that had already shown the negative effects of cannabis on cognition. It examined the impact of cannabis use on mental development in adolescents. For this, 1,037 individuals from the Dunedin Study — a New Zealand birth cohort — were followed from birth to age 38. Participants reported their cannabis use at ages 18, 21, 26, 32, and 38. Additionally, cognitive tests were conducted both before the start of use (at age 13) and after years of use (at age 38).

The study results showed that years of cannabis use were not only associated with a decline in cognitive performance but also led to a drop in IQ. Among those who regularly used cannabis before age 18, an average loss of about eight IQ points was observed between ages 13 and 38. Moreover, the changes largely persisted even after stopping cannabis use.²

More on the topic

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Conclusion

While further research is necessary to prove causality and better understand the connections, it is undeniable that cannabis — like other drugs — can negatively impact health.

Although cannabis is used in medical contexts — under expert supervision — it should not be taken lightly as a recreational or addictive substance.