Children exposed to tobacco in the womb showed more impulsive responding on attention tasks, but adding cannabis exposure did not worsen these effects and was paradoxically associated with higher short-term memory scores.
Prenatal health researchers, pediatric neuropsychologists, and parents
Cannabis co-exposure did not worsen tobacco-related attention deficits
What the researchers found
Prenatal tobacco exposure was associated with increased impulsive responding on sustained attention tasks, particularly when exposure occurred in the first trimester. Surprisingly, children co-exposed to both tobacco and cannabis showed higher short-term memory scores than non-exposed children. Cannabis co-exposure did not exacerbate the attention deficits seen with tobacco alone.
Why it matters
Most studies examine cannabis or tobacco exposure separately. This study directly compares the effects of combined exposure, finding that cannabis does not appear to add to tobacco's neurodevelopmental impact on attention. The unexpected memory finding highlights how complex prenatal exposure effects can be.
The numbers in context
133 children assessed (34 non-exposed, 37 tobacco-only, 62 co-exposed). Mean age 10.6 years. 68% Black, 20% Hispanic. Tobacco-only exposed had lower attention at first epoch. Higher first-trimester cigarettes predicted greater impulsive responding. Co-exposed had higher short-term memory vs non-exposed.
How the study worked
Longitudinal cohort study recruiting participants in the first trimester of pregnancy. Children (n=133) were assessed at ages 9-12 on sustained attention, attentional set shifting, and working memory tasks. Three groups were compared: non-exposed (n=34), tobacco-only (n=37), and tobacco-cannabis co-exposed (n=62).
What this study cannot tell us
Small sample size, particularly for the non-exposed group (n=34). Could not isolate cannabis-only exposure effects. Oversampled for co-exposure, which may limit generalizability. The unexpected memory finding needs replication before drawing conclusions.
How to read the evidence
Longitudinal design with laboratory-based cognitive assessments, but limited by small sample sizes and inability to isolate cannabis-only effects.
When this study was published
2024 study
The bigger picture
The finding that cannabis co-exposure did not worsen tobacco-related attention deficits challenges assumptions about cumulative prenatal substance harm. The perplexing memory finding may reflect selection effects, resilience factors, or genuine neurodevelopmental complexity.
Questions still open
- Why did co-exposed children show higher short-term memory? Is this a genuine effect or a statistical artifact of the small sample? Would a cannabis-only exposure group show different patterns?
Common questions
Does prenatal cannabis exposure worsen the effects of tobacco on child development?
What was unexpected about this study?
Read the original research
Prenatal tobacco and tobacco-cannabis co-exposure: Relationship with attention and memory in middle childhood.
Neurotoxicology and teratology, 104, 107371
Citation
Shisler, Shannon; Lee, Jin-Kyung; Schlienz, Nicolas J; Hawk, Larry W; Thanos, Panayotis K; Kong, Kai Ling; Leising, Meghan Casey; Eiden, Rina D. (2024). Prenatal tobacco and tobacco-cannabis co-exposure: Relationship with attention and memory in middle childhood.. Neurotoxicology and teratology, 104, 107371. https://doi.org/10.1016/j.ntt.2024.107371
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