Secondhand Cannabis Smoke Exposure: Prevalence, Personal Use, and Neurocognitive Trajectories Over Time in Adolescents in the United States.

Bastien J.; Garcia K.; Wallace A.; Sullivan R.; Hoh E.; Wade N. · medRxiv : the preprint server for health sciences · 2026

**Background & Methods** This prospective cohort study analyzed data from the Adolescent Brain Cognitive Development (ABCD) Study, following 11,316 US adolescents (776 with reported secondhand cannabis smoke [SCS] exposure) from ages 11-17 with yearly visits. Participants with SCS exposure but no personal cannabis use (n=419) were matched 1:2 to non-exposed controls (n=838) on prenatal substance exposure, family substance use history, and sociodemographics. Cognitive assessment utilized the NIH Toolbox Cognitive Battery, with linear mixed-effects models examining SCS*age interactions while controlling for sex, alcohol, nicotine, and other substance use. **Key Findings** • **Prevalence and escalation to personal use:** SCS exposure was reported in 6.9% of the full cohort; notably, 46% of SCS-exposed youth endorsed lifetime personal cannabis use by age 17, compared to 20% in non-exposed peers (OR=3.83, 95% CI: 3.29-4.44). • **Restricted cognitive development:** SCS-exposed youth demonstrated significantly reduced improvement in attention and inhibitory control over time (β=-0.32, p=.028), with domain-specific cognitive impairment comparable to secondhand tobacco smoke effects. • **Dose-response relationship:** Greater cumulative waves of SCS exposure correlated with progressively worse cognitive performance trajectories over time (β=-0.39, p=.057). **Dosage & Administration** Not reported. **Safety & Adverse Effects** The study identified impaired cognitive development as the primary adverse effect. SCS exposure was associated with restricted neurocognitive improvements in attention and inhibitory control domains during critical adolescent brain development (ages 11-17), though domain-specific effects suggest selective rather than global cognitive impact. **Evidence Quality** This preprint study provides moderate evidence with notable strengths including large sample size, longitudinal design with repeated cognitive assessments, and rigorous matching procedures controlling for confounders. Limitations include reliance on self-reported SCS exposure without biomarker validation (though toxicological testing was performed), potential selection bias in the ABCD cohort, cross-sectional nature of exposure classification at baseline, and inability to establish causality. The study's secondary finding regarding cumulative exposure showed borderline statistical significance (p=.057). As a preprint, peer review findings are unavailable. The restriction to US populations limits generalizability.

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