New research out of Western sheds light on consequences of cannabis exposure in utero

A team of researchers at London, Ont.’s Western University are uncovering how exposure to cannabis during pregnancy can affect the developing brain of a fetus.

According to a press release from Western University, a team led by PhD student Mohammed H. Sarikahya, under the supervision of Steven Laviolette from the Schulich School of Medicine & Dentistry’s department of anatomy and cell biology, set out to better understand the effects of prenatal cannabis exposure.

The research was conducted with 60 pregnant rats, and revealed that prenatal exposure to THC — the main psychoactive ingredient in cannabis — caused several severe impacts on a rat’s developing brain.

“A lot of people don’t understand that prenatal cannabis exposure hasn’t been that well researched, so we don’t really know the full impact of it on the developing brain,” said Sarikahya in a statement.

According to Laviolette, cannabis is normally assumed to be safe in pregnancy since its perception is based around it being “a natural, non-pharmacological option to reduce symptoms of nausea and anxiety.”

But despite metabolic differences, Laviolette explained that rats have a similar neuroanatomy to humans, and therefore the basic pathways for reward and emotion are the same.

The researched showed that the offspring of the THC-treated rats had major losses of omega-3 and omega-6 fatty acids in the brain, noting that the regions involved in processing emotion and anxiety were particularly impacted.

“We were very surprised at the magnitude of the impact on the brain's fatty acid signaling pathways, especially given the critical importance of this system on normal brain development," said Laviolette.

What was even more surprising to researchers was how severely the impacts of cannabis exposure varied between male and female subjects.

The male rats had a “hyperactive” dopamine system that lasted into adulthood, while the female rats did not show any abnormal results by adulthood. Dopamine helps to regulate emotion and anxiety, and therefore the team suspects the higher levels in the male could explain their more sensitive response to the effect of prenatal cannabis exposure.

“What we saw was that only the males exhibited this anxiety,” said Sarikahya. “The females weren’t completely unaffected. What we saw at childhood was that they also had severe deficits to their brain's fatty acid profile. At some point between childhood and adulthood they are able to correct these fatty acid disturbances.”

However, Sarikahya cautions that there could be other consequences of prenatal cannabis exposure for females that haven’t yet been explored. While the females were able to correct the issue, fatty acids are crucial early on for healthy brain development — when reduced, they will have an impact on the brain.

“The implication of these disturbances so early in life are worrisome given their role in brain development, but also for later-life function,” he explained.

One of the questions researchers may next want to explore is how prenatal cannabis exposure can impact addiction and this question is already on Laviolette’s mind.

“What we’re seeing is the addiction pathways are hyperactivated in the offspring following the exposure. That’s something we are going to explore in order to see how their sensitivity to various drug reward stimulus might be changed during adolescence and adulthood,” said Laviolette.

The findings were published in eNeuro, the journal of the Society for Neuroscience.