Chronic cannabis usage may have a significant negative influence on male fertility and reproductive outcomes in nonhuman primates, according to a 2022 study from Oregon Health & Science University researchers. However, it is unknown whether these effects are long-lasting. According to a new study that was just published online in Fertility & Sterility, the OHSU research team has now established that stopping the usage of THC can at least partially reverse these effects.

This is one of the first studies to show that stopping chronic THC usage can partially reverse the detrimental effects on nonhuman primates’ male reproductive health.

The principal psychoactive component of cannabis, which is one of the most widely used substances among men of reproductive age in the United States and around the world, is delta-9-tetrahydrocannabinol, or THC. But there’s a big difference.

THC consumers might not be aware of its possibly detrimental effects on their reproductive health due to a lack of safety data. This study sought to learn more about the reversibility of these effects in order to better inform healthcare professionals who counsel patients on the benefits and hazards of THC usage, particularly those who are trying to conceive.

The study’s co-author, Jamie Lo, M.D., M.C.R., is an associate professor of obstetrics and gynecology (maternal-fetal medicine), OHSU School of Medicine, and division of reproductive & developmental sciences at the Oregon National Primate Research Center. “It’s so important that we research, understand, and educate about the implications of THC on reproductive health, especially as use continues to rise among people of reproductive age and more.

In a model using nonhuman primates, researchers administered THC in progressive doses over a period of about seven months, looking specifically at changes to the tissue of the male subjects’ reproductive health organs and testes, as well as the quantity and quality of their sperm. Analyses showed that THC exposure caused a significant reduction in size of the testes and impacted male productive hormones, both which negatively impact overall fertility.

In addition, THC exposure impacted the sperm, altering the regulation of genes important for nervous system development, including those linked to autism spectrum disorder.

Interestingly, after discontinuing THC exposure over a period of about four months, researchers discovered these adverse effects were partially reversed, indicating that damage from chronic THC use can be partially restored.