A study by Upstate Medical University found that recreational cannabis use is associated with a significant 96% decrease in the odds of subjective cognitive decline among adults.

RT’s Three Key Takeaways:

  • The study found that recreational cannabis use was associated with a significant 96% reduction in the odds of experiencing subjective cognitive decline compared to non-users. 
  • This research uniquely focused on middle-aged and older adults and considered multiple facets of cannabis use: the type of use (medical vs. non-medical), the frequency, and the method of consumption (smoking, vaping, eating, or dabbing). 
  • While the study highlighted significant potential cognitive benefits from non-medical cannabis use, it also underscored the necessity for longitudinal studies to confirm these findings over time. 

A new study by Upstate Medical University researchers shows that recreational cannabis use may offer protection against cognitive decline.

The study, done by master of public health student Zhi Chen and professor Roger Wong, PhD, MPH, MSW, analyzed a large data set from the Centers for Disease Control and Prevention and found that, compared to non-users, non-medical cannabis use—such as for recreational purposes—was significantly associated with 96% decreased odds of subjective cognitive decline. 

Medical and dual (medical and non-medical) use were also associated with decreased odds of subjective cognitive decline, although not significant. Cannabis consumption frequency and method were also not significantly associated with subjective cognitive decline.

Subjective cognitive decline is an important outcome of interest as prior research shows individuals with subjective cognitive decline have a two times higher risk for dementia, which currently has no cure or definitive prevention approaches.

Study Findings and Implications

Wong says that previous studies have found negative associations between cannabis use and cognitive decline, so the results were surprising, though he was quick to point out the study had several limitations and that these results were just a snapshot of one year.

“The main takeaway is that cannabis might be protective for our cognition, but it is really crucial to have longitudinal studies because this is just a snapshot of 2021,” says Wong, assistant professor in the Department of Public Health & Preventive Medicine, in a release. “We do not know if non-medical cannabis leads to better cognition or the other way around if those with better cognition are more likely to use non-medical cannabis. We need longitudinal studies to see long-term if non-medical cannabis use is protecting our cognition over time. That’s something we don’t know yet, but that research is hindered since cannabis remains illegal federally.”

Data for this study was obtained from 4,744 US adults aged 45 and older in the 2021 Behavioral Risk Factor Surveillance System. Subjective cognitive decline was a self-reported increase in confusion or memory loss in the past year. Odds of subjective cognitive decline by cannabis use reason, frequency, and method were examined after imputing missing data, applying sampling weights, and adjusting for sociodemographic, health, and substance use factors.

Unique Contributions and Future Directions

The study differs from previous research in that it focuses on middle-aged and older adults, and it uniquely considers the three facets of cannabis use: type of use (medical or non-medical), frequency of use, and mode of use (smoking, vaping, eating, or dabbing).

“The reason I think this study is so great is we looked at all the different dimensions of cannabis use,” he says in a release. “The fact that we included all three is a huge contribution to the research because I do not believe such a study has been done before.”

Wong says he was surprised that mode and frequency had no bearing on subjective cognitive decline since other studies involving younger participants found a negative connection between brain health and cannabis use, indicating perhaps that the age of the participants plays a role in the different results.

The study, which was published in Current Alzheimer Research, was Chen’s final project in the advanced biostatistics course in the master of public health program taught by Wong. 

Study Strengths and Limitations

The authors did note some limitations with the study, including the inability to consider state-by-state cannabis regulations; thus, potential selection bias could arise if the population of certain states is either over or underrepresented due to varying measures of cannabis use.

Strengths of the study include using a national data set, which increases the generalizability of the findings. Wong says the difference in protection between medical and non-medical use comes down to the compounds that make up cannabis. Medical-grade cannabis has higher concentrations of CBD whereas non-medical has higher concentrations of THC.

Non-medical users often use cannabis to improve sleep and reduce stress. Poor sleep and chronic stress increase the risk for dementia so the protection in subjective cognitive decline could come from better sleep and stress relief that cannabis provides. Medical cannabis is used primarily for pain relief.

“Based on our findings, we don’t see the CBD in medical cannabis being beneficial for cognitive health,” Wong says in a release.

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