Sarah E. Paul and Ryan Bogdan, PhD, on Prenatal Cannabis Exposure
Prenatal cannabis exposure is associated with an increased risk of psychopathology during childhood, according to the results of a recent study.
The researchers conducted a cross-sectional study using data from a study of 11,875 children aged 9 to 11 years, 655 of whom were exposed to cannabis prenatally. Overall, this exposure was associated with an increased risk of childhood psychopathology characteristics, sleep problems, greater body mass index, and lower gray matter volume.
Consultant360 reached out to study authors Sarah E. Paul, graduate student in clinical psychology at the Behavioral Research and Imaging Neurogenetics Laboratory at Washington University in St. Louis, and Ryan Bogdan, PhD, Associate Professor of Psychological & Brain Sciences at Washington University in St Louis, St Louis, Missouri, for more information.
Consultant360: Can you tell us more about how you decided on the topic of your study, and why you thought the subject was an important one?
Sarah E. Paul and Ryan Bogdan, PhD: After alcohol, cannabis is the most widely used psychotropic drug in the U.S. The effects of alcohol use during pregnancy have been well-documented for some time, but the same cannot be said for cannabis. Alongside increases in the potency and changes to the legal landscape of cannabis, as well as diminished perception that cannabis may be harmful, the rate of cannabis use among pregnant women has risen dramatically over the past couple of decades. These trends are concerning, particularly given the shortage of well-powered studies that adequately control for potentially confounding variables. Taken together, these were our motivations in pursuing this topic of study!
C360: Why was it important to examine the effects of prenatal cannabis exposure both prior to and after maternal knowledge of pregnancy?
SEP and RB: The potential effect of cannabis on offspring outcomes may depend on when in pregnancy it was used. From early neuronal differentiation and migration (i.e., the ways in which neurons acquire their function and place in the brain) to the expression of cannabinoid receptors (i.e., where THC, the primary psychoactive component of cannabis, binds to cells), the fetal brain undergoes many changes that influences what impact cannabis might have. For these reasons, it is critically important to get a sense of when during their pregnancies the mothers used cannabis. In the ABCD study, participants are queried about substance consumption before and after their knowledge of their pregnancy. Interestingly, the average timing of this knowledge (in this sample, at an average 7 weeks) aligns with the earliest known expression of cannabinoid receptors in the human brain (approximately 5-6 weeks). Therefore, we anticipated that only cannabis use after maternal knowledge of pregnancy would have a biological mechanism (i.e., these receptors) through which to interact with the fetal brain.
C360: How do your results, particularly those involving the role of potential confounders in the relationship between prenatal cannabis exposure and childhood outcomes, add to the existing literature on the subject?
SEP and RB: With some notable exceptions, the majority of studies examining behavioral outcomes associated with prenatal cannabis exposure do not adequately control for potential confounds (e.g., family history of mental illness, timing of exposure). Here, we show that accounting for these and other variables renders many associations insignificant. We found that family history of depression and anxiety, for instance, was highly associated with many outcomes; not accounting for such variables can really bias results.
C360: What areas should future studies focus on?
SEP and RB: Although we were able to account for a host of potentially confounding variables in a large sample, our measure of the timing of cannabis use in pregnancy was crude. It will be important for future, well-powered studies to collect more precise information of cannabis use during pregnancy and follow offspring prospectively. Longitudinal analysis of prenatal cannabis exposure and childhood outcomes has thus far been rare but will be crucial in order to make progress toward testing causality. Finally, few studies of prenatal cannabis exposure collect neuroimaging data. To better understand potential mechanisms through which cannabis exposure may influence child outcomes, incorporation of neural metrics will be important.
Reference:
Paul SE, Bogdan R, et al. Associations between prenatal cannabis exposure and childhood outcomes. JAMA Psychiatry. 2021;78(1):64-76. doi:10.1001/jamapsychiatry.2020.2902