Health · Medical Research · 2 hrs ago
Children exposed to cannabis and tobacco before birth scored lower on reasoning tests
Researchers studied 8,706 US children aged 9 to 11 to examine whether exposure to cannabis and tobacco before birth was linked to later thinking skills.
The children were part of the Adolescent Brain Cognitive Development study, which follows children across the United States.
Children exposed to both substances scored lower on fluid cognition than children exposed to cannabis only or to neither substance.
Fluid cognition includes reasoning and problem-solving skills, as well as attention, memory and processing speed.
Scores for crystallized cognition did not differ significantly between the exposure groups; this measure covers acquired knowledge such as vocabulary and reading.
Mothers or caregivers reported the substance use retrospectively, so the findings show an association and do not establish that exposure caused the score differences.
Children exposed to both cannabis and tobacco before birth scored lower on fluid cognition tests than children exposed to cannabis only or neither substance.
The study found no statistically significant differences between the groups in crystallized cognition, which includes vocabulary and reading skills.
Researchers analyzed data from 8,706 children aged 9 to 11 in the US Adolescent Brain Cognitive Development study.
The findings come from a study published in the journal Addiction.
- Who
- Researchers in Quebec, Canada, studied children aged 9 to 11.
- What
- The study found lower fluid cognition scores among children exposed to both cannabis and tobacco before birth. It found no significant group differences in crystallized cognition.
- When
- The study was published on November 5, 2026.
- Where
- The children were part of the US Adolescent Brain Cognitive Development study.
- Why
- Researchers examined whether prenatal exposure to cannabis and tobacco was associated with differences in children’s cognition.
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- Final study sample
- 8,706 children
- Age range
- 9 to 11 years
- Data source
- US Adolescent Brain Cognitive Development study
- Publication
- Addiction
- Fluid cognition
- Lower scores among children exposed to both cannabis and tobacco than among children exposed to cannabis only or neither substance