DMSC study to look at implications of cannabis and alcohol use during pregnancy on prenatal brain development

Dr. Brian Christie, Division of Medical Sciences

A new study taking place in the Division of Medical Sciences at the University Of Victoria (UVic) will look at the effects of simultaneous use of alcohol and marijuana (SAM) on fetal brain development. The study, which is funded by the Catalyst Grant: Cannabis Research in Urgent Priority Areas from the Canadian Institutes of Health Research (CIHR), will help us understand how SAM may alter function and growth in key areas of the brain.

A growing number of adults aged 19 to 30 years report using cannabis, and a not-insignificant proportion of these report SAM. For young women, this could increase the risk of unplanned pregnancy. More seriously, it could increase the chance of these women engaging in potentially risky behaviours in the early stages of gestation before an individual knows they are pregnant. 

“As a public health issue, SAM is still not well recognized or understood,” explains Dr. Brian Christie, the principal investigator and professor in the Division of Medical Sciences and the Island Medical Program at UVic. “We know the effects of prenatal ethanol exposure, but cannabis is more widely available now and given the variability in products available, it can be harder to know how much people are consuming, to measure both the dose and the potency, and to assess the health implications of specific cannabinoids.”

The study, “Double Jeopardy: Effects of Prenatal Cannabis and Ethanol Exposure on hippocampus structure and function,” will build on Dr. Christie’s extensive research using models Fetal Alcohol Spectrum Disorder as well as his team’s experience in examining the role of cannabinoids in synaptic plasticity.

Cannabinoids are compounds in cannabis that act on specific neurotransmitter receptors in the brain. Commonly known cannabinoids include delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD); these exist in different cannabis varieties in varying amounts. In October 2018, the Society of Obstetricians and Gynaecologists of Canada warned that THC, a psychoactive component of cannabis, can cross the placenta and potentially cause harm to the developing fetus.

In adults, cannabis can affect synaptic function and reduce the number of synapses in the brain. Prenatal exposure to cannabinoids can alter the trajectory of early brain development, but little research exists on how SAM use during pregnancy impacts the structure and function of the hippocampus, a brain region involved in learning, memory, and emotional processes.

“We used to work to make people aware of the risks of alcohol and tobacco for a developing fetus,” explained Dr. Christie. “This generation’s issue is not dissimilar; we’re hoping that this research will provide clarity around the risks of mixed substance use, and improve public health outcomes.”

A study published by researchers at the University of British Columbia in January 2019 found that up to one third of pregnant women do not believe cannabis is harmful to their fetus; pregnant cannabis users were more likely to be under 25 years of age. According to Dr. Christie, individuals are almost twice as likely to use cannabis and alcohol simultaneously.

“We’re looking at this as an addiction issue,” explains Dr. Christie. “While cannabis proponents argue that cannabis itself is less addictive, we know that alcohol is an addictive substance. We’re hoping to uncover how cannabis and alcohol work in combination at the developmental level.”