Early Cannabis Use Strongly Predicts Arrest and Incarceration by Age 18 | Research

The takeaway

In a U.S. longitudinal study of sibling pairs, early-onset cannabis use was the strongest predictor of arrest, probation, and incarceration by age 18, even after accounting for childhood mental health disorders and family factors.

Youth prevention program designers, juvenile justice professionals, parents, policymakers

Early cannabis use predicted arrest (p = 0.013) in sibling comparisons

What the researchers found

Early-onset cannabis use strongly predicted lifetime arrest (p = 0.013), probation (p = 0.034), and incarceration (p = 0.093) by age 18. After adjusting for comorbid mental disorders and family-level unobserved factors using sibling comparisons, ADHD, ODD, and anxiety/depression were not independently associated with criminal justice contact. Only conduct disorder modestly predicted victimization. Effects were mostly driven by boys.

Why it matters

By using sibling comparisons, this study controls for family environment and shared genetics that typically confound the link between substance use and delinquency. The finding that cannabis use outpredicts childhood mental disorders for justice contact is striking.

The numbers in context

721 sibling pairs; 1997-2019 follow-up; early cannabis use predicted arrest (p = 0.013), probation (p = 0.034), incarceration (p = 0.093); effects driven by boys.

How the study worked

Longitudinal study of 721 sibling pairs from the Panel Study of Income Dynamics, followed from 1997-2019. Used sibling fixed-effects models to control for shared family environment and genetic factors. Child mental health measured by the Behavior Problems Index (ages 4-12); delinquency measured by self-reported justice system contact by age 18.

What this study cannot tell us

Mother-reported mental health measures. No information on treatment for mental disorders (especially ADHD medication). Self-reported justice contact. Cannot fully disentangle whether cannabis causes delinquency or both reflect unmeasured risk factors. Partial genetic control via sibling design.

How to read the evidence

Longitudinal sibling design with 22-year follow-up provides strong confound control, though limited by mother-reported mental health measures.

When this study was published

2025 publication with 1997-2019 data

The bigger picture

This study complicates the narrative that delinquency is primarily driven by mental health disorders. Within the same family, the sibling who started cannabis early was significantly more likely to end up in the justice system, regardless of childhood mental health status.

Questions still open

Does the criminalization of cannabis itself drive the association between early use and arrest?
Would the association weaken in states with legal cannabis?

Common questions

Does early cannabis use lead to criminal behavior?

In this sibling study, early-onset cannabis use was the strongest predictor of arrest, probation, and incarceration by age 18, even after accounting for childhood mental health problems and family factors. However, the role of cannabis criminalization in driving arrests cannot be separated from any direct effect on behavior.

Is ADHD linked to juvenile delinquency?

Surprisingly, after controlling for sibling-shared factors and comorbid conditions, ADHD showed no independent association with criminal justice contact. Early cannabis use and conduct disorder were the only significant predictors.

Read the original research

The Effects of Child Mental Health on Juvenile Criminal Justice Contact and Victimization.

The journal of mental health policy and economics, 28(1), 33-46

View on PubMed ↗

Citation

Kim, Dohyung. (2025). The Effects of Child Mental Health on Juvenile Criminal Justice Contact and Victimization.. The journal of mental health policy and economics, 28(1), 33-46.