New study reveals why cannabis use during pregnancy is a really bad idea

A new study in the journal Biological Psychiatry finds a connection between mothers who partake in cannabis use during pregnancy and abnormal brain development in their children.

Researchers at Erasmus University Medical Centre in the Netherlands looked at the brains of 54 children prenatally exposed to cannabis and found an association between thickness in the cortical region of the brain and prenatal cannabis exposure.

“Overall, we detected significant associations between prenatal cannabis exposure and brain morphology in young children, particularly in the frontal brain,” say the study’s authors.

The study involved children aged six to eight years, 96 of whom were prenatally exposed to tobacco only (without cannabis), 113 unexposed control subjects and 54 children exposed to prenatal cannabis, many of whom were also exposed to tobacco.

The researchers found that compared to non-exposed children, those exposed to tobacco had smaller brain volumes and thinner cerebral cortices (the cerebral cortex is the brain’s outermost layer of tissue responsible for advanced thought, perception, memory and awareness), while those children in the cannabis-exposed group were found to have thicker cortices but no abnormalities in brain volume.

Previous studies have investigated the long-term effects of prenatal cannabis exposure on a child’s behaviour and psychological development and found associations between cannabis exposure and a range of issues including attention and aggression problems, cognitive deficits and impairments in controlling inhibitions.

This is the first study to look into the effects prenatal exposure may have on the development of the brain itself, say the authors, who point out that considering today’s improved cannabis breeding technology has greatly increased tetrahydrocannabinol (THC) levels in common forms of the drug -the main psychoactive compound found in cannabis- further study on the effects of cannabis exposure on child neural development will be particularly important.

“The current study combined with the existing literature about the long-term consequences of prenatal cannabis and tobacco exposure support the importance of preventing and reducing smoking cannabis and cigarettes during pregnancy,” say the study’s authors.

Another recent study found that heavy users of marijuana had compromised dopamine systems, an indication of marijuana’s addictive qualities.

Researchers observed lower dopamine release in the striatum region of the cerebral cortex, involved in working memory, impulsive behaviour and attention, and found lower dopamine release, a result previously shown to be present in users of other drugs such as cocaine and heroin. “We don’t know whether decreased dopamine was a preexisting condition or the result of heavy cannabis use,” said Dr. Abi-Dargham, lead author of the study and professor of psychiatry at Columbia University Medical Center. “But the bottom line is that long-term, heavy cannabis use may impair the dopaminergic system, which could have a variety of negative effects on learning and behavior.”

Canada’s federal government intends to legalize the production, distribution and use of marijuana in the spring of 2017. Jane Philpott, Canada’s Health Minister has said legalization is important for protecting the safety of children, stating that, “We will introduce legislation that ensures we keep marijuana out of the hands of children and profits out of the hands of criminals.”

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