Those who regularly consume THC – the psychoactive ingredient in the hemp plant – may have more trouble conceiving offspring. At least that’s the case for male rhesus monkeys, to whom a team led by Jason Hedges from Oregon Health & Science University in Portland administered a certain amount of the intoxicant every day for seven months.
The dose corresponded to the dose that people who use cannabis for medicinal purposes receive. Similar to human patients, the amount was slowly increased over the course of the experiment.
“Our analysis found that THC consumption was associated with significant adverse effects on the animals’ reproductive hormones, including decreased testosterone levels and severe testicular shrinkage,” study author Jamie Lo said in a university press release. The size of the testicles in the monkeys has decreased by more than 50 percent. The higher the dose, the more pronounced the effect. The team writes that this could indicate a dose-dependent effect. Overall, the study points in a similar direction to other work showing that cannabis also affects reproductive hormones in female monkeys.
However, the results still leave some questions unanswered. For example, it is unclear whether the effect is reversible if you stop using it for a certain period of time. In addition, the data still have to be validated in a human study group. If something similar can be observed in humans, this could be particularly relevant for people who take THC for health reasons. Medicinal cannabis can be prescribed by doctors in certain exceptional cases when all other treatment options have been exhausted – for example in the case of severe migraines or other pain. In any case, the study does not say anything about whether there is a risk to fertility even with occasional smoking.