A study by Upstate Medical University suggests recreational cannabis might reduce the risk of cognitive decline, challenging earlier research and highlighting the need for longitudinal analysis.
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 (MPH) student Zhi Chen and Professor Roger Wong, Ph.D., MPH, MSW, analyzed a large data set from the CDC and found that compared to non-users, non-medical cannabis use, such as for recreational purposes, was significantly associated with 96 percent decreased odds of subjective cognitive decline (SCD). Medical and dual (medical and non-medical) use were also associated with decreased odds of SCD, although not significant. Cannabis consumption frequency and method were also not significantly associated with SCD.
Contrasting Previous Research and Exploring New Insights
SCD is an important outcome of interest as prior research shows individuals with SCD have a 2 times higher risk for dementia, which currently has no cure or definitive prevention approaches.
Wong said that previous studies have found negative associations between cannabis use and cognitive decline, so the results were surprising, though he is quick to point out the study had several limitations and that these results are 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,” said Wong, assistant professor Department of Public Health & Preventive Medicine. “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.”
Comprehensive Analysis and Study Limitations
Data for this study was obtained from 4,744 U.S. adults aged 45 and older in the 2021 Behavioral Risk Factor Surveillance System (BRFSS). SCD was a self-reported increase in confusion or memory loss in the past year. Odds of SCD 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.
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 said. “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 said he was surprised that mode and frequency had no bearing on SCD 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 MPH program taught by Wong.
“I applied the knowledge and analytical skills learned from the courses in the Public Health Methods concentration to this study,” Chen said. “Dr. Wong guided me through the process, from formulating a research question to preparing a full manuscript. I feel fortunate to have incredible professors in our program who train us to become well-rounded public health professionals with the skills for epidemiology and biostatistics work.”
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 said 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 SCD 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 said.
Reference: “Association Between Cannabis Use and Subjective Cognitive Decline: Findings from the Behavioral Risk Factor Surveillance System (BRFSS)” by Zhi Chen and Roger Wong, 23 February 2024, Current Alzheimer Research.
DOI: 10.2174/0115672050301726240219050051
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3 Comments
“…, non-medical cannabis use, …, was significantly associated with 96 percent decreased odds of subjective cognitive decline (SCD). Medical and dual (medical and non-medical) use were also associated with decreased odds of SCD, although not significant.”
The fact that the medical versus non-medical use had non-significant and significant correlations, respectively, suggests to me that what they are seeing is a spurious correlation. That is, the two groups may have resulted in self-selection. To wit, older people may be dealing with more chronic pain, which drives them to find relief and thus only using cannabis out of necessity brought on by age. What was the modal age of the two groups? Neither this article or the abstract mentions this, only that all ‘participants’ were over 45. My impression is that SCD starts to become a problem in one’s 70s and advances quickly. If the recreational users were younger, were they followed long enough to expect SCD to become common?
The Sagan Test suggests that when an extraordinary claim is made, extraordinary evidence is called for. The fact that their results are different from other research raises some flags for me.
Hallucinogenics in general are associated with potentiation of neuroplasticity are they not? Regardless, I don’t think the chronic abuse of any hallucinogen would be beneficial either. The “microdosing” long term benefits have yet play out either. Concrete studies are needed.
I would be a good candidate for these studies. I couldn’t use cannabis, during my years of nursing.. but I researched it quite a bit and compared patients use of opioids, alcohol and other drugs they may be on. The destruction/dependence, to the body/brain, seemed to be much higher on pharmaceuticals, than the natural plant. It’s legal in many states and thus knowing what you are buying, and listing the ingredients and dosages, is very important and convenient.. compared to street purchase. My doctor’s would prescribe statins, pain meds, BP, panic anxiety, Advil, seizure meds.. knowing the long term effects of pharmaceuticals, I wanted off and did so after retiring. My research of Stanley Brothers, Charlotte Web for seizures, that became my choice. I could write alot more so I’ll end with this statement… I’m off ALL those meds and have been on CBD/tumeric/ginger for 12 years, and seizure free, plus good pain relief, good sleep, no panic attacks and I can’t say enough about the positive effects of this. This year is the first year that I have increased the dose. Plus, I give this a big plus of surving Covid.