Subjective cognitive decline (SCD), “the self-reported experience of worsening or more frequent confusion or memory loss,” affects about 11% of adults over 45 years of age. Because it involves a personal perception of mental decline before the appearance of objective cognitive issues, it is often the earliest noticeable symptom of Alzheimer’s disease and dementia. Research shows that people with SCD have double the risk for dementia as those who don’t.
For this reason, SCD has become a popular topic for research into the early detection and prevention of dementia. To that end, scientists from SUNY Upstate Medical University set out to determine whether cannabis use could influence the development of SCD. Their results appeared in February in the journal Current Alzheimer’s Research.
Data for this study was obtained from 4,744 U.S. adults aged 45 and older in the CDC’s 2021 Behavioral Risk Factor Surveillance System (BRFSS) database. Researchers sorted cannabis use by reason (recreational, medical, and mixed) as well as frequency and method (smoke, eat, etc.). SCD was defined as a self-reported increase in confusion or memory loss within the past year. Odds of SCD by cannabis use reason, frequency, and method were then calculated while applying sampling weights and adjusting for sociodemographic, health, and substance use factors.
The results showed that when compared to non-users, recreational cannabis users were significantly less likely (96%) to experience SCD. Medical and mixed (medical and non-medical) use were also associated with decreased odds of SCD, although they weren’t statistically significant. Frequency and method were also not significantly associated with SCD.
Previous studies have found negative associations between cannabis use and cognitive decline, so the results were surprising, but this study differs from previous research in that it focuses on middle-aged and older adults. 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.
Conclusions
“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 researcher Roger Wong, PhD. “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 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.”
Wong said that the inability to consider state-by-state cannabis regulations was another drawback, as potential selection bias could arise if the population of certain states is either over or underrepresented due to varying measures of cannabis use.
As for the difference in protection between medical and non-medical use, Wong suggests that it might come down to the compounds that make up the cannabis. Medical-grade cannabis has higher concentrations of CBD whereas non-medical has higher concentrations of THC. “Based on our findings, we don’t see the CBD in medical cannabis being beneficial for cognitive health,” Wong said.
Wong notes that recreational cannabis is often used to improve sleep and reduce stress—two primary risk factors for dementia. Further research is needed to determine whether the cognitive-protective effects of recreational cannabis are due to improved sleep and stress relief.
