Cannabis use alters DNA methylation patterns in human sperm, providing a mechanism for transgenerational transmission of epigenomic changes that could affect offspring and potentially future generations.
Men of reproductive age who use cannabis, fertility researchers, and epigenetics scientists.
Cannabis shifts DNA methylation in sperm with hypermethylation predominating
What the researchers found
Building on the Murphy et al. findings that cannabis exposure shifts DNA methylation in both rat and human sperm (with hypermethylation predominating), this review argues this provides a mechanism for transgenerational transmission of epigenomic instability. The authors link these epigenetic changes to diverse cannabis-related teratological effects including neurological, cardiovascular, immune, and cancer-related outcomes.
Why it matters
This suggests cannabis does not just affect the user but could alter the biological blueprint passed to children through sperm, potentially affecting multiple generations.
The numbers in context
Substantial shifts in both hypo- and hypermethylation observed, with hypermethylation predominating. Linked to trends in jurisdictions including the USA, Hawaii, Colorado, Canada, France, and Australia.
How the study worked
Commentary and extended review building on Murphy et al. (2018) findings of cannabis-induced DNA methylation changes in sperm, integrating epidemiological data from the US, Hawaii, Colorado, Canada, France, and Australia.
What this study cannot tell us
Commentary building on one study. The link between sperm methylation changes and actual health outcomes in offspring is inferential, not proven. The epidemiological associations drawn are ecological and may reflect confounding.
How to read the evidence
Moderate: builds on published empirical findings in rats and humans, but extrapolations to multigenerational health effects are largely theoretical.
When this study was published
Published in 2019.
The bigger picture
If cannabis-induced epigenetic changes in sperm are inheritable, the public health implications extend far beyond the individual user. This is particularly concerning given rising cannabis use among males of reproductive age.
Questions still open
- Are these methylation changes reversible with cannabis cessation? How long does it take for sperm methylation to normalize? Do different cannabinoids (THC vs. CBD) produce different epigenetic effects?
Common questions
What is DNA methylation?
Does this mean cannabis damages sperm DNA?
Read the original research
Impacts of cannabinoid epigenetics on human development: reflections on Murphy et. al. 'cannabinoid exposure and altered DNA methylation in rat and human sperm' epigenetics 2018; 13: 1208-1221.
Epigenetics, 14(11), 1041-1056
Citation
Reece, Albert Stuart; Hulse, Gary Kenneth. (2019). Impacts of cannabinoid epigenetics on human development: reflections on Murphy et. al. 'cannabinoid exposure and altered DNA methylation in rat and human sperm' epigenetics 2018; 13: 1208-1221.. Epigenetics, 14(11), 1041-1056. https://doi.org/10.1080/15592294.2019.1633868
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