Marijuana Use During Pregnancy May Cause Abnormal Brain Structure In Offspring


Pregnant women who smoke cannabis could be risking damage to their unborn child’s brain, new research has warned.

An abnormal brain structure was discovered in children exposed to marijuana while in the womb. Compared to unexposed ones, they showed a thicker prefrontal cortex, a brain region that is involved in cognition, working memory and decision-making.

“[W]e know very little about the potential consequences of cannabis exposure during pregnancy and brain development later in life,” said study author Hanan El Marroun from Erasmus University Medical Center in the Netherlands.

This, said the researcher, proves the study important in light of the relatively common use of the substance during pregnancy. It was estimated that about 2 to 13 percent of women around the world use cannabis while pregnant. Previous studies have identified both the short and long-term behavioral effects of prenatal exposure to cannabis, yet specific brain effects remain largely a mystery.

In this study, the team used structural MRI to analyze the brains of 54 children ages 6 to 8, all prenatally exposed to marijuana and part of a population-based study in the Netherlands. Most of them were also exposed to tobacco, so the researchers compared them to 96 kids exposed to tobacco only and 113 control kids without any exposure.

There were differences seen in the cortical thickness of tobacco-exposed subjects and of tobacco and cannabis-exposed ones, revealing a separate set of effects from cannabis exposure. There was, however, no difference marked in overall brain volume of the cannabis group.

El Marroun warned that the results have to be carefully interpreted, as further data is needed to explore the link between prenatal marijuana exposure and the brain abnormalities detected. This still stresses on the importance of preventing cannabis and cigarette use while one is pregnant, she added.

The findings were detailed in the journal Biological Psychiatry.

The journal’s editor, Dr. John Krystal, pointed out cannabis’ increasing legalization, decriminalization and medical prescription as factors raising these likely risks of prenatal exposure.

Canada, for instance, could legalize recreational marijuana as early as 2017, with the government planning to file related legislation in the spring. The initiative would cover the whole country.

Other studies have highlighted cannabis’ effects on users themselves, such as having an altered ability to identify, process and empathize with emotions including happiness, sadness and anger. Compared to non-users, cannabis users showed a stronger response to faces exhibiting negative emotions such as anger and a smaller reaction to faces depicting positive emotions.

Photo: Government of Alberta | Flickr

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