University of São Paulo: Cannabis use in adolescence can cause infertility in adulthood

HFor 40 years, there has been a progressive decrease in the semen quality of the male population, a condition with multifactorial origins that can be aggravated by the use of marijuana. The toxins present in the drug, one of the most consumed in Brazil and in the world, are the subject of a study developed at USP that investigates the main causes of the hormonal imbalance that affects male fertility.

In an interview with Jornal da USP in Ar 1st Edition , Professor Jorge Hallak, from the Department of Pathology at the USP School of Medicine (FMUSP) and from the Men’s Health Study Group at the Institute for Advanced Studies (IEA) at USP; and Thiago Afonso Teixeira, PhD in Urology from FMUSP and member of the same study group; emphasize the toxic effects of marijuana on male reproductive health and disclose other risk factors that are complementary to the situation.


Hallak says there is a “soup of ingredients that have made men less fertile”, among them the environment, air pollution, lifestyle, drug use and, at an increasing level in the last decade, the marijuana use. The study carried out by FMUSP retrospectively evaluated the multiple habits of 153 men that could influence their fertile profile. “Among those evaluated, all were infertile, that is, after a year of trying with their partner, they were unable to obtain a pregnancy satisfactorily”, indicates Thiago Teixeira, author of the thesis.

The results helped the urologist to conclude that the consumption of alcohol, tobacco cigarettes and the level of sedentary lifestyle also influence testicular health, although marijuana is the factor with the greatest negative impact. “Men who smoked marijuana chronically, at least one cigarette a week for a period of one year, showed a drop in levels of estradiol, a female hormone that also exists within the male organism; an increase in prolactin, a hormone that regulates sexual desire and the reproductive part; and the increase in a protein that transports these hormones, called SHBG”, he adds.


Also according to Teixeira, it is possible to reverse male infertility, but the effectiveness of the treatment depends on the specifics of each condition. “We treat infertility as something unifactorial, which does not provide satisfactory results”, says the doctor, who argues that therapeutic interventions should consider all possible causes of sterility to guarantee the patient greater chances of getting pregnant in the usual way or through assisted reproduction methods.

The researchers are especially concerned about the reduction in the age group at which illicit substance consumption begins. “The concern is with teenagers and young adults, because the testicle, like the brain, is in formation from the beginning of puberty until the age of 22”, explains Professor Hallak. The situation is exacerbated by the significant increase in the level of tetrahydrocannabinol (THC), a neurotoxic substance, in cannabis plants: “Marijuana is much more potent today than in the past. Its THC concentration is no more than 2% or 3%, as it was in the 60s. Today, it reaches 30%”, he concludes.

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