Scientists believe that using cannabis during pregnancy could affect the memory of the unborn child. So far they have only studied the phenomenon in rats, but say their findings are cause for concern as the number of pregnant pot users has reportedly doubled in the past 15 years.
Marijuana is often touted as an effective treatment for morning sickness, but we still don’t know enough about how it might affect the unborn child to label it as safe. With marijuana becoming legalized in more and more states and countries, a team from Auburn University's Harrison School of Pharmacy decided to investigate. They presented their findings at the Society for Neuroscience annual meeting and the 2019 Experimental Biology meeting of the American Society for Pharmacology and Experimental Therapeutics.
The researchers gave THC, the psychoactive ingredient of cannabis, to pregnant rats and discovered that the compound can indeed move across the blood-placental barrier to the fetus. After the new rat pups were born, the team assessed their memories through a series of behavioral tests.
The results of the experiments showed that the juvenile rats were more forgetful than those with mothers not given THC.
“They could not perform the given task as efficiently as normal offspring of the same age,” Priyanka Pinky, lead graduate student on the project, explained. “This made us think ‘what is the reason behind this?’ We investigated further in the molecular level and we identified the culprit.”
The team turned to a specific molecule, known as the neural cell adhesion molecule, which is found in the brain. They found less of this protein in the rats born from mothers given THC. The role of neural cell adhesion molecules is to maintain the connection between the brain’s neurons and hippocampus, which is where new memories are formed. With less of this protein, the connection is dampened, hinting at why the baby rats were more forgetful.
“Research in our lab has shown that using marijuana during pregnancy has long-lasting effects on learning and memory and it can continue throughout adolescence,” said Pinky.
It’s important to remember that the new research was conducted using rats, not people, so the same effect won't necessarily be seen in human babies. However, the researchers warn that since more studies are needed to determine the true effects of cannabis use on unborn babies, it’s best to err on the side of caution and avoid using the drug while pregnant.
Previous studies have linked cannabis use in pregnancy to low birth weight, neurodevelopmental problems, and a higher risk of stillbirth, but we’re still lacking in large-scale research. Since cannabis may cause harm to unborn babies, scientists can’t exactly recruit large numbers of pregnant women and ask them to take the drug. Research has to rely on mothers accurately reporting their cannabis consumption.
Cannabis is now legal in 33 US states and the District of Columbia in one form or another, and a 2018 study found that almost 70 percent of dispensaries in Colorado recommend it as a treatment for morning sickness. Various health bodies, such as the American Medical Association, advise against its use during pregnancy; it’s simply not worth the risk.