A significant study from the University of Maryland School of Medicine in the US has revealed that prenatal exposure to marijuana could increase the risk of opioid addiction later in life. Published in Science Advances, the research shows how tetrahydrocannabinol (THC), the psychoactive ingredient in cannabis, alters fetal brain development, leading to addiction-like behaviours in adulthood.
Dr. Joseph Cheer, the study’s corresponding author, noted, “Doctors are contending with an explosion of cannabis use, and the THC content has quadrupled from what it was a generation ago. 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”. (News-medical.net)
The rising legalisation of recreational cannabis in the US has led to as many as 1 in 5 pregnant women using the drug to alleviate symptoms such as morning sickness or anxiety. However, the study warns of potential harm to the unborn child, with even moderate use—equivalent to one to two joints a day—having a lasting impact. Researchers found that THC caused dopamine neurons in the fetal brain to become hyperactive, resulting in excessive dopamine release and a sensitised reward system. This disruption increases the likelihood of opioid-seeking behaviours in later life and a higher risk of relapse linked to environmental cues.
“Doctors are contending with an explosion of cannabis use, and the THC content has quadrupled from what it was a generation ago,” said lead researcher Dr. Joseph Cheer. “This study 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.”
The study, based on preclinical animal models, illuminated how these neurobiological changes created a predisposition to addiction in adulthood. Male offspring in particular showed a stronger tendency towards addiction-like behaviours, prompting researchers to further explore sex-specific differences in these outcomes.
Currently, the American College of Obstetricians and Gynecologists recommends that healthcare practitioners caution pregnant women against cannabis use. Despite this, many women perceive cannabis as a safer alternative to traditional medications for conditions such as anxiety or pain. Dr. Mark T. Gladwin, the Dean of the University of Maryland School of Medicine, emphasised the need for additional research to guide expectant mothers. “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,” he urged. “We also need to provide better advice to pregnant patients, many of whom think this drug is safer for their baby than traditional anti-anxiety medications.”
The findings add to a growing body of evidence suggesting the risks of marijuana use during pregnancy. Researchers from the University of Maryland’s Kahlert Institute for Addiction Medicine continue to investigate strategies to mitigate the long-term consequences of prenatal THC exposure, offering hope for future interventions.
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