Prenatal THC Slowed Brain Growth in Mice From Fetus to Adulthood
Mice exposed to THC before birth showed enlarged brain ventricles as embryos, followed by slower brain growth that persisted into adulthood — with females more affected than males.
Quick Facts
What This Study Found
Using MRI brain scans at nine timepoints from gestation through adulthood, researchers tracked what happened to mouse brains after prenatal THC exposure. The trajectory was consistent and concerning.
THC-exposed embryos first showed ventriculomegaly — enlarged fluid-filled spaces in the brain. After birth, this shifted to a deceleration of overall brain growth that persisted through development and into adulthood. Female mice were more affected than males across multiple measures.
The brain regions most consistently impacted spanned both cortex and subcortex, aligning with observed behavioral changes. THC-exposed neonates showed sex-dependent differences in social behavior, and by adolescence, exposed mice displayed increased anxiety-like behavior.
Electron microscopy confirmed structural changes at the cellular level, providing a biological basis for the behavioral observations and suggesting the effects extend beyond gross brain volume to cellular architecture.
Key Numbers
9 MRI timepoints from gestation to adulthood. Ventriculomegaly observed in embryos. Sustained brain growth deceleration through adulthood. Female mice more affected than males. Behavioral changes: altered social behavior in neonates, increased anxiety-like behavior in adolescents.
How They Did This
Longitudinal study in mice using MRI brain imaging at nine timepoints from gestation to adulthood. Combined with behavioral assays (social behavior in neonates, anxiety-like behavior in adolescents) and electron microscopy for cellular-level analysis. THC was administered prenatally; controls received vehicle.
Why This Research Matters
This is one of the most comprehensive longitudinal mappings of prenatal THC's effects on brain development available — tracking the same animals from embryo to adult across nine MRI timepoints. The finding that effects are not transient but sustained into adulthood, and that females may be more vulnerable, adds important detail to the prenatal exposure literature (connecting to RTHC-00226 on molecular brain changes and RTHC-00209 on neurodevelopmental outcomes).
The Bigger Picture
The prenatal THC research is building a convergent picture across methods and models. Molecular studies (RTHC-00226) show THC changes brain chemistry at the molecular level. This imaging study shows those changes translate to altered brain structure and growth trajectories. Human neuroimaging studies from the ABCD cohort (RTHC-00241) are beginning to show similar patterns in children. Together, these studies suggest prenatal THC exposure initiates a cascade that begins with molecular disruption and manifests as lasting structural and behavioral differences.
What This Study Doesn't Tell Us
Animal model — mice metabolize THC differently than humans, and brain development timelines differ significantly. THC doses may not directly translate to human exposure levels. The study cannot account for the complex social and environmental factors that influence human neurodevelopment alongside any biological effects of prenatal exposure.
Questions This Raises
- ?What drives the sex difference in vulnerability — hormonal factors, differences in endocannabinoid system development, or something else?
- ?Do the brain growth deficits stabilize in adulthood or continue to diverge?
- ?Would different THC doses or exposure windows produce different trajectories?
Trust & Context
- Key Stat:
- Evidence Grade:
- Longitudinal animal study with rigorous multi-modal methodology (MRI, behavioral testing, electron microscopy) — strong within the animal model framework but requires caution when extrapolating to humans.
- Study Age:
- Published in 2026 in Molecular Psychiatry, representing the current frontier of prenatal THC brain imaging research in animal models.
- Original Title:
- Impact of prenatal delta-9-tetrahydrocannabinol exposure on mouse brain development: a fetal-to-adulthood magnetic resonance imaging study.
- Published In:
- Molecular psychiatry, 31(1), 256-269 (2026) — Molecular Psychiatry is a well-respected journal focusing on the intersection of neuroscience and psychiatry.
- Authors:
- Cupo, Lani(3), Vecchiarelli, Haley A(4), Gallino, Daniel(2), VanderZwaag, Jared, Bradshaw, Katerina, Phan, Annie, Khakpour, Mohammadparsa, Ben-Azu, Benneth, Guma, Elisa, Fouquet, Jérémie P, Spring, Shoshana, Nieman, Brian J, Devenyi, Gabriel A, Tremblay, Marie-Eve, Chakravarty, M Mallar
- Database ID:
- RTHC-08194
Evidence Hierarchy
Follows a group of people over time to track how outcomes develop.
What do these levels mean? →Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-08194APA
Cupo, Lani; Vecchiarelli, Haley A; Gallino, Daniel; VanderZwaag, Jared; Bradshaw, Katerina; Phan, Annie; Khakpour, Mohammadparsa; Ben-Azu, Benneth; Guma, Elisa; Fouquet, Jérémie P; Spring, Shoshana; Nieman, Brian J; Devenyi, Gabriel A; Tremblay, Marie-Eve; Chakravarty, M Mallar. (2026). Impact of prenatal delta-9-tetrahydrocannabinol exposure on mouse brain development: a fetal-to-adulthood magnetic resonance imaging study.. Molecular psychiatry, 31(1), 256-269. https://doi.org/10.1038/s41380-025-03189-5
MLA
Cupo, Lani, et al. "Impact of prenatal delta-9-tetrahydrocannabinol exposure on mouse brain development: a fetal-to-adulthood magnetic resonance imaging study.." Molecular psychiatry, 2026. https://doi.org/10.1038/s41380-025-03189-5
RethinkTHC
RethinkTHC Research Database. "Impact of prenatal delta-9-tetrahydrocannabinol exposure on ..." RTHC-08194. Retrieved from https://rethinkthc.com/research/cupo-2026-impact-of-prenatal-delta9tetrahydrocannabinol
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.