Summary: A new study suggests that prenatal exposure to cannabis may influence brain development and long-term mental health.
The researchers used data from the ABCD study to examine neuroimaging of children exposed to cannabis in utero. They discovered potential biological mechanisms, including altered brain structure and inflammation, that could contribute to behavioral problems.
The study highlights the complexity of the link between prenatal cannabis exposure and later mental health outcomes.
Highlights:
- Impact of prenatal exposure: Exposure to cannabis in utero may alter brain development and increase mental health risks.
- Perspectives in neuroimaging: Changes in brain structure and inflammation were observed in exposed children.
- Complex factors: Differentiating the effects of cannabis from genetics and environment remains a challenge.
Source: WUSTL
Scientists are trying to understand how cannabis may affect long-term neurodevelopment when people are exposed to it in the womb. Previous work by University of Washington researchers Sarah Paul and David Baranger in the Behavioral Research and Neurogenetic Imaging (BRAIN) Lab led by Ryan Bogdan has linked prenatal cannabis exposure to potential mental health problems in childhood and adolescence, but the potential biological mechanisms that could explain this association have been unclear.
In research published in Nature Mental Health This month, Bogdan, a dean’s professor emeritus of psychology and brain sciences at Washington University in St. Louis, and postdoctoral researcher Baranger, describe some of these potential mechanisms, the intermediate biological steps that might play a role in how prenatal cannabis exposure leads to behavioral problems later in life.
“We have evidence that cannabis exposure can influence brain development, which is consistent with associations with mental health,” Baranger said.
Determining the long-term effects of cannabis exposure during pregnancy is not straightforward. There are many confounding factors that affect mental health and behavior.
For example, if a person was exposed to cannabis in utero and later develops attention deficit disorder in adolescence, how do we differentiate between a hereditary trait or a trait influenced by environmental factors and a trait influenced by cannabis exposure early in development? Or all three processes could contribute to eventual psychopathology.
Another complication is the increasing prevalence of cannabis use, including among the pregnant population, where cannabis use increased from 3 to 7% between 2002 and 2017.
The researchers used statistical methods to filter out some of these confounding factors and suggest potential biological links between prenatal cannabis exposure and adolescent behavior patterns.
Nothing can establish 100% causality, “but we can look at the plausibility of causality and identify potential biological correlates associated with cannabis exposure and these mental health effects suggests that it is plausible,” Bogdan said of the study’s findings.
The researchers used data from the Adolescent Brain and Cognitive Development (ABCD) study, an ongoing research project that includes nearly 12,000 children across the United States.
In the study, researchers collected data on each mother’s substance use before birth and neuroimaging data at ages 9-10 and 11-12. About 370 children were exposed to cannabis before their mothers knew they were pregnant, and 195 were exposed before and after they learned they were pregnant.
The researchers looked at a variety of neuroimaging measures important to brain development, including measurements of brain thickness and surface area, as well as measurements of water diffusion in and out of cells. The trends observed in the group of children exposed to cannabis before birth are consistent with potential reductions in neuroinflammation.
“It’s possible that what we’re seeing is an anti-inflammatory effect of cannabis that’s driving differences in how the brain is pruned during neurodevelopment,” Bogdan said.
Much has been made of the anti-inflammatory effects of cannabis, but reducing inflammation isn’t always beneficial. It’s all about timing. Reducing inflammation too much at the wrong time could affect how the brain is pruned and primed.
Another theory is that cannabis exposure accelerates aging. But don’t expect to find biological clues that link mental health disorders to early cannabis exposure.
It might not be a matter of size. It might also be that it’s not the cannabis use itself, but rather the after-burn products of smoked cannabis that could trigger accelerated aging and downstream cognitive effects, Bogdan said.
Or maybe it’s all due to sociological factors.
Trying to find the one-to-one link that proves that prenatal cannabis exposure has negative effects during adolescence is challenging and may not be possible with retrospective studies.
Baranger notes that the main limitation of this dataset is that it is retrospective; mothers reported their cannabis use 10 years ago, so he looks forward to new data from prospective and longitudinal studies that will offer more recent, accurate, and detailed information on cannabis use during pregnancy.
“This will potentially give us more answers to these questions in the future.”
In the meantime, the results of this study reiterate that if you’re considering using cannabis during pregnancy, “talk to your doctor about your choices and what other options may be available to you,” Baranger said.
Funding: The research reported in this press release was funded by R01DA54750 (RB, AA). Additional funding included: DAAB (K99AA030808), APM (T32DA015035), AJG (DGE-213989), SEP (F31AA029934), ASH (K01AA030083), ECJ (K01DA051759; BBRF Young Investigator Grant 29571), CER (R01DA046224), AA (R01DA54750), RB (R01DA54750, R21AA027827, U01DA055367). Data for this study were provided by the Adolescent Brain Cognitive Development (ABCD) study, which was funded by grants U01DA041022, U01DA041025, U01DA041028, U01DA041048, U01DA041089, U01DA041093, U01DA041106, U01DA041117, U01DA041120, U01DA041134, U01DA041148, U01DA041156, U01DA041174, U24DA041123, and U24DA041147 from the NIH and other federal partners (https://abcdstudy.org/federal-partners.html).
The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
About this news on research in CUD and developmental neuroscience
Author: Lea Shaffer
Source: WUSTL
Contact: Leah Shaffer – WUSTL
Picture: Image credited to Neuroscience News
Original research: Access closed.
“Prenatal Cannabis Exposure Is Associated with Localized Brain Differences That Partially Contribute to Associations with Increased Adolescent Psychopathology” by Ryan Bogdan et al. Nature Mental Health
Abstract
Prenatal cannabis exposure is associated with localized brain differences that partially contribute to increased psychopathology in adolescents
Prenatal cannabis exposure (PCE) is associated with mental health problems in early adolescence, but possible neurobiological mechanisms remain unknown.
In a large longitudinal sample of adolescents (aged 9–12 years, not= 9,322–10,186), we find that PCE is associated with localized differences in gray and white matter of the frontal and parietal cortices, their associated white matter tracts, and resting-state striatal connectivity, even after accounting for potential confounders related to pregnancy, family, and child.
Variability in forceps minor and pars triangularis diffusion parameters partially longitudinally mediates associations between PCE and attention problems and symptoms of attention deficit hyperactivity disorder.
Differences in brain development related to PCE may confer vulnerability to poorer mental health in early adolescence.