Daily THC edible exposure throughout pregnancy in rhesus macaques was associated with significant alterations in fetal brain growth, histological changes, and molecular dysregulation of axonal guidance pathways.
Obstetricians, developmental neuroscientists, prenatal exposure researchers
THC disrupted axonal guidance pathways in primate fetal brains
What the researchers found
THC exposure was associated with significant age-by-sex interactions in brain volumetric growth on MRI, differences in fetal brain histology suggestive of dysregulation, and two extracellular vesicle-associated miRNAs in fetal CSF linked to dysregulated axonal guidance and netrin signaling pathways.
Why it matters
This is one of the first studies to use a primate model with THC edibles, closely approximating human exposure patterns. The convergence of MRI, histological, and molecular findings strengthens the evidence that prenatal THC disrupts neurodevelopment.
The numbers in context
n=5 per group; daily THC edibles from pre-conception through pregnancy; 4 MRI timepoints; 2 miRNAs identified in fetal CSF; pathway analysis linked to axonal guidance and netrin signaling.
How the study worked
Rhesus macaques received daily THC edibles pre-conception through pregnancy (n=5 THC, n=5 control). Fetal MRI at gestational days 85, 110, 135, and 155. Cesarean delivery at G155 with collection of CSF for miRNA analysis and tissue for histology.
What this study cannot tell us
Small sample (n=5 per group). Cannot determine long-term neurodevelopmental outcomes from fetal measures. THC edible dose may not match typical human consumption. No assessment of postnatal behavior.
How to read the evidence
Primate model with multi-modal assessment (MRI + histology + molecular), limited by small sample size.
When this study was published
2024 publication
The bigger picture
Rhesus macaque brain development is far more similar to human than rodent models. The identification of specific molecular pathways (axonal guidance, netrin signaling) gives mechanistic insight into how THC may alter fetal brain wiring.
Questions still open
- Do the axonal guidance disruptions persist into postnatal brain development?
- Are the sex-specific effects on brain growth clinically significant in human pregnancies?
Common questions
Does THC affect fetal brain development?
How does prenatal THC affect the developing brain?
Read the original research
Prenatal delta-9-tetrahydrocannabinol exposure alters fetal neurodevelopment in rhesus macaques.
Scientific reports, 14(1), 5808
Citation
Ryan, Kimberly S; Karpf, Joshua A; Chan, Chi Ngai; Hagen, Olivia L; McFarland, Trevor J; Urian, J Wes; Wang, Xiaojie; Boniface, Emily R; Hakar, Melanie H; Terrobias, Jose Juanito D; Graham, Jason A; Passmore, Scarlet; Grant, Kathleen A; Sullivan, Elinor L; Grafe, Marjorie R; Saugstad, Julie A; Kroenke, Christopher D; Lo, Jamie O. (2024). Prenatal delta-9-tetrahydrocannabinol exposure alters fetal neurodevelopment in rhesus macaques.. Scientific reports, 14(1), 5808. https://doi.org/10.1038/s41598-024-56386-7
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