Cannabis Use During Pregnancy Altered Fetal Brain Connectivity Patterns | Research

The takeaway

Fetal brain imaging of 115 fetuses found that prenatal cannabis exposure was associated with altered hippocampal connectivity to frontal, temporal, and cingulate brain regions, with patterns linked to less favorable developmental outcomes.

Obstetricians, developmental neuroscientists, prenatal health researchers

Prenatal cannabis exposure altered fetal brain connectivity patterns linked to less favorable developmental outcomes

What the researchers found

Fetuses exposed to cannabis prenatally showed altered hippocampal connectivity to dorsolateral, medial, and superior frontal cortex, insula, anterior temporal, and posterior cingulate regions. The connectivity patterns in exposed fetuses were more often associated with less favorable outcomes at age 5.

Why it matters

This is among the first studies to show that prenatal cannabis exposure may alter brain connectivity before birth, suggesting that developmental effects begin in utero rather than emerging only after delivery.

The numbers in context

115 fetuses; mean gestational age 32.2 weeks; 43% female; cannabis-exposed group showed altered connectivity to frontal, temporal, insular, and cingulate regions; connectivity patterns in exposed group linked to less favorable age-5 outcomes.

How the study worked

Prospective fetal fMRI study of 115 fetuses (mean 32.2 weeks gestation, 43% female) with prenatal drug toxicology data, using voxelwise hippocampal connectivity analysis in age- and sex-matched subsets.

What this study cannot tell us

Small sample for subgroup analyses; fetal fMRI is technically challenging with potential motion artifacts; cannot separate cannabis effects from other co-occurring factors; outcome classification at age 5 was preliminary.

How to read the evidence

Novel fetal neuroimaging study with preliminary evidence, limited by small subgroup sizes and technical challenges of fetal fMRI.

When this study was published

Fetal imaging with age-5 outcome follow-up.

The bigger picture

If cannabis is altering fetal brain wiring during a critical period of development, it provides a biological mechanism for the behavioral and cognitive differences observed in children with prenatal cannabis exposure.

Questions still open

Do these fetal connectivity changes persist into childhood? Is there a threshold of prenatal cannabis exposure below which connectivity remains normal?

Common questions

Does cannabis during pregnancy affect the baby's brain before birth?

This study found altered brain connectivity patterns in fetuses exposed to cannabis, particularly in connections between the hippocampus and frontal brain regions. These patterns were associated with less favorable developmental outcomes at age 5.

What parts of the brain were affected?

Cannabis exposure was associated with altered connectivity from the hippocampus (important for memory) to frontal regions (important for decision-making), the insula (emotional processing), and the cingulate cortex (attention and emotion regulation).

Read the original research

Miswiring the brain: Human prenatal Δ9-tetrahydrocannabinol use associated with altered fetal hippocampal brain network connectivity.

Developmental cognitive neuroscience, 51, 101000

View on PubMed ↗Publisher’s paper ↗

Citation

Thomason, Moriah E; Palopoli, Ava C; Jariwala, Nicki N; Werchan, Denise M; Chen, Alan; Adhikari, Samrachana; Espinoza-Heredia, Claudia; Brito, Natalie H; Trentacosta, Christopher J. (2021). Miswiring the brain: Human prenatal Δ9-tetrahydrocannabinol use associated with altered fetal hippocampal brain network connectivity.. Developmental cognitive neuroscience, 51, 101000. https://doi.org/10.1016/j.dcn.2021.101000