Hair Testing Reveals 7% of 15–16-Year-Olds in the U.S. Use Cannabis Heavily | Research

The takeaway

The nationwide ABCD Study found that biochemically verified moderate-to-heavy cannabis use affected 7.1% of 15–16-year-olds, with self-report matching hair toxicology only 45% of the time at that age — suggesting substantial underreporting.

Epidemiologists, adolescent health researchers, school counselors, and policymakers relying on substance use survey data.

What the researchers found

Weighted estimates from hair toxicology showed 7.1% of 15–16-year-olds had moderate-to-heavy cannabis use, 4.7% had heavy nicotine use, and 0.3% had heavy alcohol use. Correspondence between self-report and hair testing improved with age (from <1% at 11–12 to 45% at 15–16), indicating significant underreporting of substance use in younger adolescents.

Why it matters

This is one of the first nationally representative estimates of adolescent substance use verified by biological testing rather than just self-report. The finding that self-report dramatically underestimates actual use means survey-based prevalence data may significantly undercount teen cannabis use.

The numbers in context

11,868 participants tracked from ages 9–10 to 15–16. 6,133 unique participants provided hair samples (11,865 total samples). By ages 15–16: 7.1% moderate+ cannabis, 4.7% heavy nicotine, 0.3% heavy alcohol. Self-report/toxicology correspondence: <1% at ages 11–12, 45% at ages 15–16.

How the study worked

Data from the nationwide ABCD Study (n=11,868 at baseline ages 9–10, followed to ages 15–16 at Wave 6). Hair samples from 6,133 unique participants (11,865 samples) objectively detected substance use. Multi-step weighting estimated national prevalence, adjusting for recruitment demographics, missed visits, and sample testing.

What this study cannot tell us

Hair testing detects moderate-to-heavy use but may miss occasional use. Some adolescents may have too short hair for testing. Weighted estimates depend on modeling assumptions. Cannot distinguish frequency from intensity of use.

How to read the evidence

Large, nationally representative longitudinal study with biological verification, providing the strongest available evidence for adolescent substance use prevalence.

When this study was published

Published 2025, data from ABCD Study 2016–2024.

The bigger picture

If more than half of 15–16-year-old cannabis users don't accurately self-report, then surveys like Monitoring the Future and YRBSS may substantially underestimate teen cannabis use. This has major implications for how we measure the effectiveness of prevention programs and policy changes.

Questions still open

How much higher is actual teen cannabis use than survey estimates suggest? Would routine biomarker screening change our understanding of substance use trends? Should prevention program evaluations incorporate biological verification?

Common questions

Do teens lie about cannabis use on surveys?

Rather than intentional lying, the low correspondence likely reflects a combination of underreporting, different recall periods (surveys ask about recent use while hair captures months of exposure), and varying definitions of 'use' between self-report and biological detection.

Is 7% of teens a lot?

For moderate-to-heavy cannabis use verified by hair testing at ages 15–16, 7.1% is significant. This represents the heaviest users — the total proportion who have tried cannabis at least once is likely much higher.

Read the original research

Prevalence of Biochemically-Verified Substance Use in Healthy Adolescents Across the United States: Hair Toxicology Results in the ABCD Study.

medRxiv : the preprint server for health sciences

View on PubMed ↗Publisher’s paper ↗

Citation

Wade, Natasha E; Si, Yajuan; Tapert, Susan F; Linkersdörfer, Janosch; Lisdahl, Krista M; Moore, Hailley R; Tally, Laila; Das, Biplabendu; Huestis, Marilyn A; Wallace, Alexander L; Sullivan, Ryan M; Szpak, Veronica; Zhang, Le; Ziemer, Laura R; Thompson, Wesley K. (2025). Prevalence of Biochemically-Verified Substance Use in Healthy Adolescents Across the United States: Hair Toxicology Results in the ABCD Study.. medRxiv : the preprint server for health sciences. https://doi.org/10.1101/2025.09.19.25336190