Even modest, short-term THC exposure in male rats before mating produced long-lasting attention deficits in their adult offspring, suggesting epigenetic transmission through sperm.
Men considering fatherhood who use cannabis, reproductive health researchers, and epigeneticists.
Attention deficits in adult offspring
What the researchers found
Paternal THC exposure (2 mg/kg/day for 12 days) did not affect litter size, sex ratio, birth weight, or survival, but caused significant, long-lasting impairment in attentional performance and increased habituation of locomotor activity in adult offspring.
Why it matters
Most research on cannabis and reproduction focuses on maternal exposure. This study demonstrates that paternal cannabis use before conception can also affect offspring through epigenetic changes in sperm, expanding the scope of reproductive risk.
The numbers in context
2 mg/kg/day oral THC for 12 days (described as modest dose and brief period). Significant attention impairment detected in offspring during adulthood. No effects on clinical health markers at birth.
How the study worked
Male rats received oral THC (2 mg/kg/day for 12 days) or vehicle before mating. Offspring were tested in adulthood for attention (operant task) and locomotor behavior. Previous work from the same group confirmed THC-associated changes in sperm DNA methylation.
What this study cannot tell us
Rat model with single dose level and duration. Mechanism (epigenetic transmission) is inferred from companion methylation study but not directly proven in this behavioral study. Only male offspring behavioral data presented.
How to read the evidence
Preliminary: single animal study, though supported by companion epigenetic data in rats and humans.
When this study was published
Published in 2019.
The bigger picture
The companion human study from the same research group found similar epigenetic changes in sperm of men who smoke cannabis, raising the possibility that these animal findings translate to human fathers.
Questions still open
- At what point before conception must a father stop using cannabis to avoid these effects? Do these epigenetic changes persist across multiple generations?
Common questions
Can a father's cannabis use affect his children?
Were the offspring physically affected?
Read the original research
Paternal THC exposure in rats causes long-lasting neurobehavioral effects in the offspring.
Neurotoxicology and teratology, 74, 106806
Citation
Levin, Edward D; Hawkey, Andrew B; Hall, Brandon J; Cauley, Marty; Slade, Susan; Yazdani, Elisa; Kenou, Bruny; White, Hannah; Wells, Corinne; Rezvani, Amir H; Murphy, Susan K. (2019). Paternal THC exposure in rats causes long-lasting neurobehavioral effects in the offspring.. Neurotoxicology and teratology, 74, 106806. https://doi.org/10.1016/j.ntt.2019.04.003
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