Prenatal exposure to tobacco and marijuana were both associated with worse behavioral scores in children, and tobacco exposure specifically altered the connectivity between brain networks involved in attention and self-reflection.
Developmental neuroscientists, pediatricians screening for prenatal exposure effects, educators working with children who have behavioral challenges.
What the researchers found
Using data from 6,674 children in the ABCD Study, researchers examined how prenatal substance exposure related to both behavioral outcomes and brain functional connectivity.
Both prenatal tobacco exposure (PTE) and prenatal marijuana exposure were associated with worse behavioral scores on the Child Behavior Checklist. Household income and food insecurity also predicted worse scores, highlighting that substance exposure effects occur alongside socioeconomic disadvantage.
The brain connectivity analysis revealed a specific finding for prenatal tobacco: PTE was significantly associated with increased connectivity between the default mode network (DMN) and dorsal attention network (DAN), and decreased connectivity within the DMN itself. The DMN is active during self-referential thinking and mind-wandering; the DAN manages focused attention. Altered connectivity between these networks has been linked to attention difficulties and other neurodevelopmental problems.
Critically, the same DMN-DAN connectivity changes were also associated with worse behavioral scores — suggesting a pathway from prenatal exposure through altered brain connectivity to behavioral outcomes.
Why it matters
This study connects three levels of analysis — prenatal exposure, brain network organization, and behavioral outcomes — in a single large cohort. The finding that prenatal tobacco exposure both alters brain connectivity and predicts behavior problems through those same connectivity changes suggests a biological pathway from in utero exposure to childhood difficulties.
The numbers in context
6,674 children analyzed. Prenatal tobacco and marijuana exposure both associated with worse behavioral scores. PTE specifically linked to increased DMN-DAN connectivity and decreased intra-DMN connectivity. Same connectivity patterns associated with behavioral problems. Income and food insecurity also significant predictors.
How the study worked
Observational study using ABCD Study data (6,674 children). Behavioral scores from Child Behavior Checklist tested for associations with prenatal substance exposure and demographics. Resting-state fMRI assessed functional network connectivity. Linear regression with false discovery rate correction for multiple comparisons.
Who was studied
N=6,674 children aged 9-10, mixed sex, from the Adolescent Brain Cognitive Development Study in the US.
What this study cannot tell us
Cross-sectional brain-behavior analysis within a longitudinal cohort — cannot confirm causal direction. Prenatal exposure based on maternal retrospective report. Cannot fully disentangle prenatal substance effects from postnatal environmental factors (parenting, continued exposure, socioeconomic factors). The high co-occurrence of tobacco and marijuana use during pregnancy makes it difficult to isolate each substance's independent effects.
How to read the evidence
Large observational study linking prenatal exposure to brain connectivity and behavior — multi-level analysis strengthens the evidence but cross-sectional design limits causal interpretation.
When this study was published
Published in 2026 using ABCD Study data, providing integrated exposure-brain-behavior analysis in a contemporary cohort.
The bigger picture
This adds a functional connectivity dimension to the prenatal exposure story. The mouse MRI study (RTHC-00236) showed structural changes; the ABCD connectivity study (RTHC-00241) showed altered network patterns with prenatal cannabis; and now this study shows that altered DMN-DAN connectivity may mediate the path from exposure to behavioral outcomes. The prenatal timing study (RTHC-00256) showed substance-specific critical windows — this study shows substance-specific brain network effects.
Replication
Not stated in abstract.
Funding
Not reported in abstract.
Conflicts of interest
Not reported in abstract.
Questions still open
- Does prenatal marijuana exposure produce its own specific brain connectivity signature distinct from tobacco? Do the DMN-DAN connectivity changes persist or resolve as children develop? Could early identification of altered connectivity patterns guide targeted interventions for exposed children?
Read the original research
Child Behavioral Scores Correlate With Prenatal Tobacco and Marijuana Exposure, Sociodemographic Variables and Interactions of Default Mode and Dorsal Attention Networks.
Brain and behavior, 16(1), e71168
Brain and Behavior is a peer-reviewed journal focusing on the intersection of neuroscience and psychology.
Citation
Vishnubhotla, Ramana V; Zhao, Yi; Radhakrishnan, Rupa. (2026). Child Behavioral Scores Correlate With Prenatal Tobacco and Marijuana Exposure, Sociodemographic Variables and Interactions of Default Mode and Dorsal Attention Networks.. Brain and behavior, 16(1), e71168. https://doi.org/10.1002/brb3.71168
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