In the national ABCD Study, THC concentrations in adolescent hair predicted shorter sleep duration and more strength exercise a year later, with effects differing between males and females.
Adolescent health researchers, pediatricians, substance use epidemiologists
THC and CBD showed opposite associations with exercise in adolescents
What the researchers found
Among 2,262 youth ages 9-15, greater hair THC concentrations predicted more frequent strength exercise one year later; greater CBD concentrations predicted fewer strength exercise days; and greater THCCOOH concentrations predicted shorter sleep duration. Effects differed by sex: among males, THC and THCCOOH predicted shorter sleep; among females, THC and THCCOOH predicted strength exercise frequency and THC predicted shorter sleep. Concurrently, THCCOOH concentration was associated with greater internalizing and externalizing symptoms.
Why it matters
Hair analysis provides an objective measure of cannabis exposure over months, avoiding the limitations of self-report. Finding that different cannabinoids (THC vs CBD) have opposite associations with exercise, and that effects differ by sex, suggests cannabis exposure during adolescence has complex, sex-specific health implications.
The numbers in context
n=2,262 youth ages 9-15 (49% female); THC predicted more strength exercise; CBD predicted fewer exercise days; THCCOOH predicted shorter sleep duration; concurrent THCCOOH associated with greater internalizing and externalizing symptoms
How the study worked
Analysis of hair toxicology data from three cannabinoid analytes (THC, CBD, THCCOOH) and multiple health measures in the Adolescent Brain Cognitive Development (ABCD) Study. Two-part linear regression models assessed effects on externalizing/internalizing symptoms, exercise, asthma, and sleep. Stratified by sex with false discovery rate corrections.
What this study cannot tell us
Observational associations cannot establish causation; youth who use cannabis may differ from non-users in unmeasured ways. Hair cannabinoid levels may reflect environmental exposure (secondhand smoke), not just personal use. False discovery rate corrections were applied but multiple comparisons increase chance of spurious findings.
How to read the evidence
Large nationally representative sample with objective biomarkers and prospective design provides moderate confidence, though observational design and potential for environmental exposure in hair samples are limitations.
When this study was published
2025 publication from the ongoing ABCD Study
The bigger picture
The ABCD Study is the largest long-term study of adolescent brain development in the US. These findings from objective hair biomarkers reinforce concerns about adolescent cannabis exposure while adding nuance that THC and CBD may have distinct and even opposing effects on health behaviors.
Questions still open
- Why did THC and CBD show opposite associations with exercise frequency? Are the sex differences in cannabinoid-health associations driven by biological differences in the endocannabinoid system or by gendered patterns of use?
Common questions
Why use hair instead of urine or blood tests?
Did boys and girls show different effects?
Read the original research
Cannabinoids in hair and their prospective association with mental and physical health outcomes in adolescents.
Neurotoxicology and teratology, 108, 107433
Citation
Aks, Isabel R; Patel, Herry; Pelham, William E; Huestis, Marilyn A; Wade, Natasha E. (2025). Cannabinoids in hair and their prospective association with mental and physical health outcomes in adolescents.. Neurotoxicology and teratology, 108, 107433. https://doi.org/10.1016/j.ntt.2025.107433
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