September 24, 2025
Impact of prenatal delta-9-tetrahydrocannabinol exposure on mouse brain development: a fetal-to-adulthood magnetic resonance imaging study
Lani Cupo and Dr. Mallar Chakravarty have recently identified distinct alterations in specific brain cell populations in individuals exposed to prenatal delta-9-tetrahydrocannabinol (THC). Their study, published in Molecular Psychiatry, employs longitudinal imaging from fetal through adulthood stages to reveal how early THC exposure disrupts the developmental trajectories of cortical neurons.
Here’s an overview of the study.
Takeaway
Using cannabis during pregnancy may subtly impact weight gain, brain development, and behaviour of the unborn child
Background
The legalization of cannabis and cannabis-related products has impacted the way in which the use of these products are perceived. Pregnant people, in particular, are increasingly seeing these products as a more “natural” method for managing anxiety, mood, or the symptoms of morning sickness, such as nausea and vomiting. Many medical professionals advise against cannabis use during pregnancy, however no clear evidence-based guidelines exist that consider both the well-being of the mother and the unborn child.
Methods
Our lab studied mice born to mothers that were chronically exposed to THC early in pregnancy, the chemical compound that is found in cannabis that causes the “high” and is thought to be linked to many of its perceived wellness effects. Using cutting-edge magnetic resonance imaging (MRI) techniques we reconstructed a lifespan trajectory from before birth to adulthood. We also examined the behaviour of these mice after they were born to determine if they had altered anxiety-like and social behaviours.
Results
Across the lifespan, we found changes in the size and weight of mice, their brain volume, and their behavior. Mice that had been exposed to THC were smaller while still in the womb, which can have life-long consequences. They also had larger ventricles, the fluid-filled cavities inside the brain that can often be used as an index of developmental abnormalities. After birth, they gained more weight, but their brain volume grew at a slower rate than mice that were not exposed to cannabis. In cannabis exposed adolescence and adulthood, brain volume did somewhat return towards normal, especially in the male mice. Early in life cannabis-exposed mice showed problems with social behavior, and female adolescents, in particular, showed anxiety-like behavior, again, especially in the females.
Interpretation
Our experiments suggest that using cannabis during pregnancy may have life-long consequences for the unborn child. These effects are somewhat nuanced, as they may improve later in life, and the sex of the baby may be important in determining the long-term effects.
Conclusion
These results provide an important step in understanding long-term impacts of cannabis use during pregnancy, but more research is needed to understand the impact of small or infrequent cannabis use on the same outcomes. Additionally, there is a need to do more studies on the impact of cannabis on the health and well-being of the mother.
About the study
“Impact of prenatal delta-9-tetrahydrocannabinol exposure on mouse brain development: a fetal-to-adulthood magnetic resonance imaging study” by Lani Cupo and Mallar Chakravarty et al., was published in Molecular Psychiatry.