Secondhand cannabis and tobacco exposure linked to lower cognitive scores in youth | Research

The takeaway

Among 5,580 youth in the ABCD Study, secondhand and environmental exposure to cannabis and tobacco smoke was associated with worse cognitive performance, even without direct use.

Parents, pediatricians, public health officials, and policymakers concerned about children's exposure to cannabis smoke.

5,580 youth; secondhand cannabis exposure linked to lower cognitive performance

What the researchers found

Secondhand cannabis and tobacco exposure in youth were independently associated with lower cognitive performance across multiple domains, suggesting passive exposure may carry cognitive risks during brain development.

Why it matters

As cannabis legalization increases, more children may be exposed to secondhand cannabis smoke. If passive exposure affects cognition during critical brain development periods, it has major implications for household cannabis policies.

The numbers in context

N=5,580 youth from ABCD Study. Both secondhand cannabis and tobacco exposure associated with lower cognitive performance scores.

How the study worked

Cross-sectional analysis of ABCD Study year-2 follow-up data (N=5,580, 48% female). Assessed cognitive performance in relation to secondhand or environmental exposure to cannabis and tobacco smoke.

What this study cannot tell us

Cross-sectional design cannot establish causation. Exposure was likely measured via self/parent report. Children exposed to secondhand smoke may differ from unexposed children in many ways (family socioeconomic status, other environmental exposures). Cannot distinguish direct effects of smoke exposure from correlated household factors.

How to read the evidence

Large well-established cohort study. Cross-sectional design and potential confounding limit causal inference.

When this study was published

Published 2023.

The bigger picture

Decades of research established the harms of secondhand tobacco smoke. The equivalent research for cannabis is just beginning. These early findings from the largest US youth brain study suggest similar concerns may apply to cannabis.

Questions still open

What level of secondhand cannabis exposure produces measurable cognitive effects? Would longitudinal ABCD data show progressive cognitive impact with continued exposure?

Common questions

Can secondhand cannabis smoke affect children's brains?

This study found an association between secondhand cannabis exposure and lower cognitive scores in nearly 6,000 youth. While it cannot prove the smoke caused the cognitive differences, it raises concerns that parallel established findings about secondhand tobacco smoke and child development.

How are children exposed to secondhand cannabis smoke?

Children can be exposed when adults use cannabis in shared living spaces, vehicles, or outdoor areas near children. With increasing legalization and the finding that many households lack cannabis-free air rules, children's exposure may be growing.

Read the original research

Clouding Up Cognition? Secondhand Cannabis and Tobacco Exposure Related to Cognitive Functioning in Youth.

Biological psychiatry global open science, 3(2), 233-242

View on PubMed ↗Publisher’s paper ↗

Citation

Wade, Natasha E; McCabe, Connor J; Wallace, Alexander L; Gonzalez, Marybel R; Hoh, Eunha; Infante, M Alejandra; Mejia, Margie Hernandez; Haist, Frank. (2023). Clouding Up Cognition? Secondhand Cannabis and Tobacco Exposure Related to Cognitive Functioning in Youth.. Biological psychiatry global open science, 3(2), 233-242. https://doi.org/10.1016/j.bpsgos.2022.01.010