Does cannabis use have an impact on cognitive decline? Danish study over 44 years says no

Cannabis, often criticized for its effects on short-term memory, may not have the negative impact on long-term brain health that many believe. A study carried out by the University of Copenhagen, Denmark and published in the journal Brain and Behavior last month, found that cannabis users showed slightly less cognitive decline from early adulthood to late middle age compared to non-users. The research involved more than 5.000 men and looked at a range of parameters over 44 years.

Surprisingly, neither the age of onset of cannabis use nor the frequency of use had a significant impact on cognitive aging. These findings challenge traditional myths and open the door for further research into the complex relationship between cannabis use and cognitive function.

The study, conducted over four decades with a group of Danish men, explored changes in IQ scores as a measure of cognitive decline. The results revealed several noteworthy insights:

• Cognitive decline: Cannabis users recorded a 1,3 point decrease in IQ over 44 years compared to non-users;
• Age of onset: Starting to use cannabis before the age of 18 had no measurable impact on long-term cognitive performance.
• Ffrequency of consumption: Even frequent cannabis use (at least twice a week) was not associated with faster cognitive decline.

Cannabis users show better preservation of IQ levels over time

Contrary to popular belief, cannabis — often classified as a drug with a high potential for abuse — may not be as harmful to cognitive health as previously thought. The researchers analyzed intelligence test results at two key points in the participants’ lives: early adulthood (around age 20) and late middle age (around age 64).

Cannabis users demonstrated a slight advantage in preserving their IQ levels over time. When accounting for lifestyle variables such as education level, baseline IQ, and substance use, cannabis was not shown to have any detrimental effect on cognitive decline.

Busting the myth of cannabis and cognition

For decades, cannabis has been linked to short-term memory impairment and cognitive problems. However, this study challenges that narrative, suggesting that the long-term effects of cannabis on brain health are more subtle. Here are the key findings:

• Age of initiation of cannabis use: Initiating cannabis use in adolescence or adulthood did not significantly worsen cognitive decline over time.
• Frequency of consumption: Regular cannabis use, even several times a week, is not associated with more pronounced cognitive decline.
• Education and lifestyle: Baseline IQ, educational background, and general lifestyle appear to have a more significant impact on cognitive aging than cannabis use itself.

Although the observed differences were modest, they raise important questions about how cannabis interacts with brain health, particularly during the aging process.

The role of lifestyle factors in cognitive decline

The University of Copenhagen research also highlights the importance of broader lifestyle and environmental factors in cognitive aging. While cannabis use did not have any negative effects, other variables such as education, physical health and mental engagement played a key role in determining brain outcomes.

This highlights the fact that cannabis, while a significant factor, is only one piece of the cognitive aging puzzle. Researchers believe a more holistic approach is needed to understand brain health over time.

Study limitations and implications for future research on cannabis and cognition

While these findings provide compelling evidence, the researchers stress the need for further studies to validate the results in different populations and age groups. Some areas for future exploration include:

• Differences between generations: This study focused exclusively on men. Further research could explore whether the results apply to women.
• Cannabis potency: The study did not take into account changes in cannabis potency over the decades, which may influence cognitive outcomes.
• Long-term effects in a modern context: As cannabis legalization increases around the world, understanding its long-term effects remains crucial.

What does this mean for cannabis consumers?

For current and future users, the study offers reassurance that long-term, moderate consumption does not have a significant impact on cognitive function. However, the researchers stress the need for responsible use and further research to confirm these findings in broader demographic samples.

Although cannabis use has often been stigmatized, these findings suggest that its impact on cognitive health is much less detrimental than previously thought. In fact, under certain conditions, cannabis users may experience slightly better cognitive outcomes as they age.

It’s a complex and nuanced relationship. The 44-year Danish study provides valuable insights into the long-term effects of cannabis on cognitive decline. While the differences between cannabis users and non-users were modest, the results challenge traditional assumptions about cannabis as a significant threat to brain health.

Most importantly, the study highlights the need to examine other factors, such as education, lifestyle and baseline cognitive abilities, when assessing cognitive aging. Future research will help refine our understanding of cannabis and its role in maintaining cognitive health.

However, the results serve as a reminder that the relationship between cannabis and cognition is complex and that simplistic assumptions about its harmful effects may no longer be true.

Other studies corroborate the Danish research

The Danish research is not, however, the only one to suggest that cannabis may reduce the risk of cognitive decline. A Upstate Medical University study also found that recreational cannabis use may protect the brain, showing that non-medicinal users of the plant were significantly less likely to suffer from Subjective Cognitive Decline (SCD).

The aim of this study was to examine whether motive, frequency, and method of cannabis use were associated with subjective cognitive decline (SCD). Data were obtained from 4.744 US adults aged 45 years and older in the 2021 Behavioral Risk Factor Surveillance System (BRFSS). SCD was a self-reported increase in confusion or memory impairment in the past year. The odds of SCD by motive, frequency, and methods of cannabis use (e.g., smoking, eating, vaping) were examined using multiple logistic regression after imputing missing data, applying sample weights, and adjusting for sociodemographic, health, and substance use covariates.

In terms of concrete results, and compared to non-users, non-medical cannabis use was significantly associated with a 96% reduction in the odds of DCS (aOR = 0,04, 95% CI = 0,01-0,44, p < 0,01). Medical use (aOR = 0,46, 95% CI = 0,06-3,61, p = 0,46) and dual medical and non-medical use (aOR = 0,30, 95% CI = 0,03 -2,92, p = 0,30) were also associated with a decrease in the odds of DCS, although not significant. However, frequency and method of cannabis use were not significantly associated with DCS, challenging previous research and highlighting the need for more longitudinal analyses.

According to Roger Wong, assistant professor in the Department of Public Health and Preventive Medicine at Upstate Medical University and one of the study’s authors, “The main takeaway is that cannabis may protect our cognition, but it’s really crucial to have longitudinal studies because this is just a snapshot from 2021. We don’t know whether non-medical cannabis leads to better cognition or the opposite, whether those with better cognition are more likely to use non-medical cannabis. We need longitudinal studies to see in the long term whether non-medical cannabis use is protecting our cognition over time. That’s something we don’t know yet, but that research is hampered because cannabis remains illegal at the federal level [in the US],” he concluded.

Read the full study from the University of Copenhagen below:
Brain and Behavior - 2024 - Høeg - Cannabis Use and Age‐Related Changes in Cognitive Function From Early Adulthood to Late

____________________________________________________________________________________________________

____________________________________________________________________________________________________

What do you do with €3 a month? Become one of our Patrons! If you believe that independent cannabis journalism is necessary, subscribe to one of the levels of our Patreon account and you will have access to unique gifts and exclusive content. If there are many of us, we can make a difference with little!

João Xabregas

More postsBiography

With a professional background in CAD technical drawing (2D and 3D), João Xabregas is an activist and advocate for all uses and applications of cannabis. He discovered and entered the world of cannabis during his youth, where he developed a special interest in the cultivation of the plant, which led him on a journey of self-learning through the world of cannabis that continues to this day. His adventures linked to cannabis cultivation began with the same goal as many others: to be able to guarantee the quality and eliminate any possible risks to his health of what he consumed, as well as to avoid any type of dependence on the illicit market. However, he quickly began to view the world of cannabis and everything related to it with a very different perspective. He admits the enormous passion he has for the most persecuted plant in the world and about which he is always willing to write and have a good conversation.

• João Xabregas

  https://cannareporter.eu/author/joaoxabregas/

  SOMAÍ and Universidade Lusófona publish peer-reviewed study to improve practices in the production of full-spectrum cannabis oils
• João Xabregas

  https://cannareporter.eu/author/joaoxabregas/

  RAW Founder Josh Kesselman Buys High Times Magazine for $3,5 Million
• João Xabregas

  https://cannareporter.eu/author/joaoxabregas/

  Systematic review addresses risks and benefits of medicinal cannabis in mental health
• João Xabregas

  https://cannareporter.eu/author/joaoxabregas/

  South Korea: Researchers identify new cannabinoid 'cannabielsoxa' and discover anti-tumor potential of other cannabinoids in neuroblastoma