What topics does this cannabis study cover?

This study covers research on: Neuroprotection, THC, Mental Health.

Cannabis may slow teenage brain development during critical growth years

Q: Where was this research published?

Published in Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology on April 20, 2026.

Longitudinal neurocognitive trajectories in a large cohort of youth who use cannabis: combining self-report and toxicology.

Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology • April 20, 2026 • Moderately Relevant

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AI Summary

This comprehensive study examined how cannabis use during adolescence affects brain development and cognitive abilities in 11,036 youth aged 9-17, using both self-reported data and objective toxicological testing to verify cannabis exposure. Researchers tracked changes in cognitive performance across multiple domains—including memory, processing speed, inhibitory control, and language—over time as participants developed. By accounting for numerous confounding factors like family history of substance use disorder, prenatal exposures, and other drug use, the study provides one of the most rigorous examinations to date of cannabis's impact on the developing teenage brain.

The key finding reveals a concerning pattern: adolescents who use cannabis show altered cognitive development trajectories, with reduced improvement or flattening of gains over time compared to non-users. Importantly, the study suggests cannabis users actually started with slightly better cognitive performance in late childhood, but their cognitive abilities failed to improve at normal rates as they aged. When examining specific cannabinoids, THC exposure was associated with worse episodic memory over time compared to controls, while CBD exposure showed no significant difference from controls, suggesting that THC may be the primary driver of cognitive concerns.

This research provides critical insights for parents, policymakers, and adolescents themselves by demonstrating that cannabis use during the teenage years—a period of crucial brain development—may compromise the normal strengthening of cognitive abilities that typically occurs through the late teens and early twenties. The use of toxicological testing alongside self-reports strengthens confidence in these findings, as it captures actual cannabis exposure rather than relying solely on what participants report using. Future research tracking this cohort into adulthood will clarify whether these developmental delays persist and whether the age of first use influences long-term cognitive outcomes.

📄 Original Abstract

Adolescents experience extensive neurocognitive development, with cannabis use potentially impacting developmental trajectories. Here, we comprehensively assess the influence of adolescent cannabis use onset on neurocognitive trajectories and consider how recent delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) may influence neurocognition. We use the large, diverse longitudinal Adolescent Brain Cognitive Development (ABCD) Study dataset, combining self-reported substance use with objective toxicological tests (hair, urine, breath, oral fluid). Longitudinal mixed methods of the full cohort (n = 11,036, ages 9-17; 47% Female/53% Male) investigate time-varying cannabis onset on neurocognitive performance. Primary model covariates include sociodemographics, family history of substance use disorder, prenatal substance exposure, early psychopathology, other substance use, and nesting for participant ID, study site, and family ID. Secondarily, in participants with repeat toxicological hair testing (n = 645; 38% Female/62% Male) at ages 12-16, we consider the influence of THC v. CBD v. Controls. Primary models included false discovery rate corrections (FDR-p < .05) while secondary models were interpreted at p < .01. Cannabis group interacted with age to show altered neurocognitive trajectories across domains (immediate recall and delayed memory, processing speed, inhibitory control, visuospatial processing, language, and working memory; βs = -0.11- -0.52). Secondary models indicated hair-identified THC exposure*age predicted worse episodic memory than in Controls (β = -0.60, p = .007), with no difference between CBD exposed and Controls. Data suggest those who use cannabis show likely pre-existing better cognitive performance during late childhood, with reduced improvement or flattened trajectories over time. These neurocognitive trajectories in youth (ages 9-17) who initiate cannabis use were demonstrated after accounting for within-person change and numerous known confounds and improving accuracy in identifying cannabis use through incorporating toxicological measures. Continued monitoring of this cohort will clarify cannabinoid-cognition relationships into young adulthood, including the impact of timing of cannabis use initiation.

Paper Type

📄 Research

Publication

Journal: Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology
Published: April 20, 2026
PMID: 42002627
DOI: 10.1038/s41386-026-02395-1

Authors (12)

Natasha E Wade Department of Psychiatry, University of California, San Diego, La Jolla, CA, USA. nwade@health.ucsd.edu.
Ryan M Sullivan Department of Psychiatry, University of California, San Diego, La Jolla, CA, USA.
Alexander L Wallace Department of Psychiatry, University of California, San Diego, La Jolla, CA, USA.
Rachel Visontay The Matilda Centre for Research in Mental Health and Substance Use, The University of Sydney, Sydney, NSW, Australia.
Veronica Szpak Department of Psychiatry, University of California, San Diego, La Jolla, CA, USA.
+7 more authors