Non-medical cannabis use linked to dramatically lower self-reported cognitive decline in older adults | Research

The takeaway

Among 4,744 US adults aged 45+, non-medical cannabis use was associated with 96% lower odds of subjective cognitive decline, though the effect was not significant for medical or combined use.

People interested in cannabis use among older adults and cognitive health.

96% lower odds of cognitive decline with non-medical use (likely biased)

What the researchers found

Non-medical cannabis use was associated with 96% decreased odds of subjective cognitive decline (aOR=0.04, 95% CI: 0.01-0.44, p<.01). Medical use (aOR=0.46) and dual use (aOR=0.30) showed similar trends but were not statistically significant. Cannabis frequency and method of use were not associated with SCD.

Why it matters

The dramatic association between non-medical cannabis use and lower reported cognitive decline is striking but likely reflects selection bias or confounding rather than a true protective effect. Still, it raises questions worth investigating in longitudinal research.

The numbers in context

4,744 adults aged 45+. Non-medical use aOR=0.04 (96% lower odds, p<.01). Medical use aOR=0.46 (not significant). Dual use aOR=0.30 (not significant). Frequency and method were not significant.

How the study worked

Cross-sectional analysis of 4,744 US adults aged 45+ from the 2021 BRFSS survey. Subjective cognitive decline was self-reported increase in confusion or memory loss. Logistic regression adjusted for sociodemographic, health, and substance use factors.

What this study cannot tell us

Cross-sectional design cannot establish causation. The extremely large effect size (96% reduction) raises concern about reverse causation (people with cognitive decline stopping recreational use). Subjective cognitive decline is self-reported and may not correlate with objective measures. Small numbers of cannabis users limit power.

How to read the evidence

Cross-sectional survey with self-reported outcomes. The extremely strong association almost certainly reflects confounding or reverse causation rather than a true causal effect of cannabis on cognition.

When this study was published

Published in 2024 using 2021 BRFSS data.

The bigger picture

As cannabis use grows among older adults, understanding its relationship to cognitive health is important. While this cross-sectional finding is intriguing, the extremely strong association (96% reduction) likely reflects that people who notice cognitive decline stop using cannabis recreationally, rather than cannabis preventing decline.

Questions still open

Does the association reflect reverse causation (people with cognitive issues stopping recreational cannabis)? Would objective cognitive testing show the same pattern? Does the reason for use truly matter, or are non-medical users simply healthier overall?

Common questions

Does cannabis prevent cognitive decline?

This study found an association between recreational cannabis use and lower self-reported cognitive decline, but the cross-sectional design means it likely reflects reverse causation: people experiencing memory problems probably stop using cannabis recreationally.

Why was only non-medical use significant?

Medical cannabis users may have underlying health conditions that contribute to cognitive decline, while recreational users tend to be healthier overall. This difference in baseline health likely explains the different associations.

Read the original research

Association Between Cannabis Use and Subjective Cognitive Decline: Findings from the Behavioral Risk Factor Surveillance System (BRFSS).

Current Alzheimer research, 20(11), 802-810

View on PubMed ↗Publisher’s paper ↗

Citation

Chen, Zhi; Wong, Roger. (2024). Association Between Cannabis Use and Subjective Cognitive Decline: Findings from the Behavioral Risk Factor Surveillance System (BRFSS).. Current Alzheimer research, 20(11), 802-810. https://doi.org/10.2174/0115672050301726240219050051