Prenatal Marijuana Exposure Linked to Brain White Matter Changes in 10-Year-Olds | Research

The takeaway

In a large neuroimaging study from the ABCD cohort, children prenatally exposed to marijuana showed reduced white matter integrity and smaller cortical surface area in brain regions critical for motivation, cognitive skills, and emotional processing.

Prenatal care providers; neurodevelopmental researchers studying in-utero exposures.

418 exposed vs 667 control children showed significantly reduced white matter integrity in corticostriate tracts

What the researchers found

Prenatally exposed children (n=418) showed significantly reduced white matter integrity (lower fractional anisotropy and neurite density, higher mean and radial diffusivity) compared to 667 matched controls. The most affected tracts were the superior corticostriate tract and projections to frontal and parietal cortices. Cortical surface area was reduced in the left parahippocampal and right postcentral gyri.

Why it matters

This is one of the largest neuroimaging studies of prenatal marijuana exposure to date. The finding that white matter tracts connecting motivation and goal-directed behavior centers are specifically affected suggests a biological pathway through which prenatal cannabis exposure could impair executive function as children enter adolescence.

The numbers in context

1,085 children (418 exposed, 667 controls). Mean age 9.9 years (SD 0.6). Significantly reduced FA and neurite density. Higher mean and radial diffusivity. Most affected: superior corticostriate tract, external capsule projections to frontal/parietal cortices. Reduced cortical surface area in left parahippocampal and right postcentral gyri.

How the study worked

Cross-sectional neuroimaging study using ABCD Study data. 1,085 children (mean age 9.9 years): 418 prenatally exposed to marijuana, 667 matched controls with no prenatal exposure. Diffusion MRI assessed white matter microstructure. Mixed linear models accounted for multiple covariates.

What this study cannot tell us

Cross-sectional design cannot determine whether prenatal marijuana exposure caused the brain differences. Prenatal exposure was typically assessed by maternal report and may be underreported. Other prenatal exposures (tobacco, alcohol, stress) may confound results despite statistical control.

How to read the evidence

Strong: large demographically diverse multicenter cohort with advanced diffusion MRI and statistical modeling, though cross-sectional design limits causal claims.

When this study was published

2025 study using ABCD Study data.

The bigger picture

The corticostriate tracts affected in this study connect prefrontal cortex to reward/motivation centers. As these children enter adolescence -- when executive function demands increase dramatically -- these structural differences could become functionally consequential, potentially affecting academic performance, decision-making, and risk-taking behaviors.

Questions still open

Will these white matter differences translate into functional cognitive impairments as children enter adolescence? Do the brain structural changes worsen, stabilize, or improve over time?

Common questions

What is white matter and why does it matter?

White matter is the brain's wiring -- bundles of nerve fibers that connect different brain regions. Reduced white matter integrity means these connections are weaker, potentially slowing communication between brain areas involved in motivation, planning, and emotional processing.

Does this mean prenatal marijuana definitely harmed these children's brains?

The study found associations, not proof of causation. The structural differences could reflect prenatal cannabis exposure, shared genetic factors, or other environmental exposures during pregnancy. However, the specificity of the affected tracts (motivation and goal-directed behavior circuits) aligns with known cannabinoid receptor distribution in the developing brain.

Read the original research

The Effect of Prenatal Marijuana Exposure on White Matter Microstructure and Cortical Morphology during Late Childhood.

AJNR. American journal of neuroradiology, 46(10), 2176-2185

View on PubMed ↗Publisher’s paper ↗

Citation

Acosta-Rodriguez, Hector; Bobba, Pratheek; Zeevi, Tal; Ment, Laura R; Payabvash, Seyedmehdi. (2025). The Effect of Prenatal Marijuana Exposure on White Matter Microstructure and Cortical Morphology during Late Childhood.. AJNR. American journal of neuroradiology, 46(10), 2176-2185. https://doi.org/10.3174/ajnr.A8774