According to the results of a new study, prenatal exposure to tetrahydrocannabinol (THC) causes a rewiring of the fetal brain and may increase one’s risk of developing opioid addiction later in life. The study, led by researchers at the University of Maryland School of Medicine (UMSOM), was published in the journal Science Advances and showed that in-utero exposure to THC caused some brain cells to release more dopamine, which resulted in increased responsiveness to cues associated with reward, such as food or an opioid drug.
Specifically, the study’s findings showed that rats exposed to THC in the womb experienced more dopamine release when exposed to opioid drugs as adolescents compared to those that were never exposed to THC. The study found that rats that were previously exposed to THC in utero showed a significantly increased motivation to press a lever that would deliver a dose of opioid drugs compared to animals that were not previously exposed to THC. In addition, when THC-exposed animals reached adolescence, they were more likely to show enhanced opioid-seeking behaviour and were more likely to seek out opioid-associated environmental cues compared to those animals who were not exposed to THC in the womb. Finally, they were also more likely to develop persistent addiction-like behaviours, and had higher levels of dopamine released in the brain’s reward system.
Some recent research studies estimate that up to 18% of pregnant women in the U.S. use cannabis during pregnancy to alleviate symptoms such as morning sickness, lower back pain, and anxiety. Evidence has been growing, however, to suggest that tetrahydrocannabinol (THC), the main psychoactive ingredient in cannabis, poses risks to the developing fetus by impacting brain development.
“Doctors are contending with an explosion of cannabis use, and the THC content has quadrupled from what it was a generation ago,” Dr. Joseph Cheer, the study’s corresponding author and professor of neurobiology and psychiatry at the University of Maryland School of Medicine in a press release. “It demonstrates the enduring consequences that prenatal cannabis exposure exerts on the brain’s reward system, which ultimately results in a neurobiological vulnerability to opioid drugs.”
Currently, the guidelines released by the American College of Obstetricians and Gynecologists recommend that doctors counsel patients regarding the concerns about potential adverse health consequences of continued use of cannabis during pregnancy.
“We need to more fully understand the enduring effects of THC exposure in the womb and whether we can reverse some of the deleterious effects through CRISPR-based gene therapies or repurposed drugs,” said UMSOM Dean Dr. Mark T. Gladwin in the press release. “We also need to provide better advice to pregnant patients, many of whom are using cannabis to help control anxiety because they think this drug is safer for their baby than traditional anti-anxiety medications.”
