Summary: New research from Washington University in St. Louis links maternal cannabis use during pregnancy to a modestly higher risk that a child will show signs of psychosis around age 10. The study also provides insight into how endocannabinoid signaling may influence early brain development.
Source: Washington University in St. Louis
Key finding: Pregnant women who use cannabis may slightly increase the likelihood that their child will exhibit psychosis proneness in middle childhood, according to a study led by researchers at Washington University in St. Louis.
“Our analysis indicates that prenatal marijuana exposure after a mother becomes aware of her pregnancy is associated with a small increase in psychosis proneness by about age 10,” said Jeremy Fine, an undergraduate in psychological and brain sciences and the study’s lead author.
National data show marijuana use among pregnant women has risen substantially in recent years. A prior Washington University School of Medicine study reported a 75 percent increase in past-month marijuana use among pregnant people in the United States between 2002 and 2016. As cannabis laws change and availability increases, some dispensaries have promoted cannabis as a remedy for pregnancy-related nausea, a practice that has raised public health concerns.
Published March 27 in JAMA Psychiatry, the current study advises caution: because many questions remain about cannabis’ effects on fetal development, pregnant people should be discouraged from using cannabis at any point during pregnancy.
Importantly, the findings point to a possible developmental window: prenatal exposure may be riskier once the fetal brain begins to express endocannabinoid receptors — the targets through which THC, marijuana’s main psychoactive compound, produces its effects.
“One potential explanation for the increased psychosis risk after maternal awareness of pregnancy is that the fetal endocannabinoid receptor system may not be established in very early pregnancy,” said Ryan Bogdan, associate professor of psychological and brain sciences and senior author. “If the type 1 endocannabinoid receptor is not expressed until later in the first trimester, exposure to THC before receptor expression might have less impact than exposure after the system begins to develop.”
Bogdan’s BRAIN Lab has previously contributed to basic research showing that endocannabinoid signaling plays a role in neurogenesis and neuronal migration — processes that shape brain structure and connectivity during early development. These biological roles make it plausible that disrupting endocannabinoid signaling with prenatal THC exposure could influence later neurodevelopmental outcomes.
“This study raises the possibility that there are developmental windows during which cannabis exposure is more likely to increase psychosis risk,” Bogdan said.
THC mimics naturally occurring endocannabinoids and binds to their receptors. Animal studies indicate that THC crosses the placenta and that the type 1 endocannabinoid receptor appears at a stage roughly equivalent to 5–6 weeks of human gestation. In this study, mothers reported learning of their pregnancy on average at about 7.7 weeks, a timing that could explain why exposure after knowledge of pregnancy was associated with increased psychosis proneness in children.
The analysis used baseline data from the Adolescent Brain Cognitive Development (ABCD) Study, a large, ongoing longitudinal project tracking child health and brain development across the United States. Researchers analyzed survey responses from 3,774 mothers covering 3,926 pregnancies and measured psychosis liability in 4,361 children born between 2005 and 2008. Child outcomes were assessed by questionnaire when children were between about 8.9 and 11 years old.
Of the 4,361 children included, 201 (4.61 percent) had reported prenatal exposure to marijuana. Among those exposed, most (138) were exposed only before the mother knew she was pregnant, while two were exposed only after pregnancy knowledge.
The authors note several important limitations. The number of prenatally exposed children in the sample was small, and maternal self-report may underestimate cannabis use. The study lacked detailed, precise information on timing, dose, frequency and potency of cannabis exposure, and it did not determine whether childhood psychosis proneness later converts to clinical psychosis. Data were also incomplete for some potential confounders such as maternal stress levels and parental genetic risk for psychotic disorders.
“This research is correlational and does not establish causation,” said Allison Moreau, a graduate student and co-author. “However, the association between prenatal cannabis exposure after pregnancy awareness and higher psychosis proneness in children persisted after adjusting for many potential confounders — including maternal education, prenatal vitamin use, prenatal alcohol and nicotine use, and child substance use — which makes the possibility of a contributing effect more plausible.”
The study reinforces public-health guidance that pregnant people should think carefully before using cannabis. “Given rising cannabis accessibility and potency, along with growing perceptions that cannabis use is safe, further research is urgently needed to map potential harms and benefits across development,” Bogdan said. “Until more is known, the association we observed between prenatal marijuana use and a small increase in psychosis proneness supports advising against cannabis use during pregnancy.”
Co-authors from Washington University include Nicole Karcher, Arpana Agrawal, Cynthia Rogers, and Deanna Barch, representing psychiatry and psychological and brain sciences departments.
Funding: This analysis used data from the Adolescent Brain Cognitive Development (ABCD) Study, funded by awards from the National Institutes of Health and other federal partners.
Source:
Washington University in St. Louis
Media Contacts:
Gerry Everding – Washington University in St. Louis
Image Source:
The image is in the public domain.
Original Research: Closed access
“Association of Prenatal Cannabis Exposure With Psychosis Proneness Among Children in the Adolescent Brain Cognitive Development (ABCD) Study” — Jeremy D. Fine; Allison L. Moreau, BA; Nicole R. Karcher, PhD; Arpana Agrawal, PhD; Cynthia E. Rogers, MD; Deanna M. Barch, PhD; Ryan Bogdan, PhD. JAMA Psychiatry. 2019. doi: 10.1001/jamapsychiatry.2019.0076
Abstract
Reported past-month marijuana use among pregnant women in the U.S. rose from 2.85% in 2002 to 4.98% in 2016. While cannabis use has been linked to psychosis in adults, prenatal exposure is less well understood. Given rising prenatal use and evidence that endocannabinoids are important for brain development, this study evaluates whether prenatal cannabis exposure is associated with psychosis proneness in childhood.