Most Young Adult Cannabis Users Are "Uncontrolled" Users, But Self-Regulation Rules Increase After Legalization
A 9-year study of LA young adults found two distinct classes: "Controlled" users who followed self-imposed rules (no use before work/school, no driving high) and "Uncontrolled" users. The Uncontrolled class was always the majority, but some self-regulation rules increased after legalization.
Quick Facts
What This Study Found
Two latent classes emerged: Controlled and Uncontrolled, becoming more distinct over time. The Uncontrolled class was the majority across all waves. "No school/work" and "no driving" rules increased over time. "Stopping cannabis use" rule decreased during legalization transition. Controlled users consistently used less cannabis and had lower problematic use scores.
Key Numbers
366 at wave 1 to 193 at wave 8; 2 latent classes across all waves; Uncontrolled always majority; "no school/work" and "no driving" rules increased; "stopping use" rule decreased.
How They Did This
Prospective LA-based cohort aged 18-26 at enrollment. 8 survey waves over 9 years. Four waves analyzed across policy transitions: 2014-2015 (medical only), 2017-2018 (transition), 2019-2020 (adult use), 2022-2023 (adult use). Latent class analysis on 5 controlled-use rules.
Why This Research Matters
As cannabis becomes legal, understanding whether users self-regulate is crucial. The finding that some harm-reduction rules increased post-legalization (no work/school, no driving) while the ability to stop using decreased suggests legalization may shift self-regulation patterns in complex ways.
The Bigger Picture
Legalization appears to promote certain harm-reduction behaviors (avoiding use at work or while driving) while potentially normalizing continuous use (less ability/motivation to stop). This has implications for how prevention messaging should evolve in legal markets.
What This Study Doesn't Tell Us
LA-specific cohort may not generalize. Attrition from 366 to 193 over 9 years. Self-reported rules may not reflect actual behavior. Latent class analysis requires assumptions about class structure.
Questions This Raises
- ?Did legalization cause the shift in self-regulation, or do changing attitudes explain both?
- ?Should prevention efforts focus on promoting controlled-use rules rather than abstinence?
Trust & Context
- Key Stat:
- Uncontrolled users were the majority across all 9 years
- Evidence Grade:
- Prospective cohort spanning a natural policy experiment provides strong longitudinal evidence, though attrition and single-city sample add limitations.
- Study Age:
- 2025 publication analyzing 9 years of data (2014-2023) spanning cannabis policy transitions.
- Original Title:
- Controlled Use of Cannabis Among Young Adults in Los Angeles Across Changes in Cannabis Policies.
- Published In:
- International journal of mental health and addiction (2025)
- Authors:
- Lankenau, Stephen E(16), Ataiants, Janna(11), Prince, Mark, Fedorova, Ekaterina, Conn, Bridgid M, Ansell, Emily, Wong, Carolyn F
- Database ID:
- RTHC-06894
Evidence Hierarchy
Follows a group of people over time to track how outcomes develop.
What do these levels mean? →Frequently Asked Questions
Do cannabis users set rules for themselves?
Yes. This study identified two classes: Controlled users who followed self-imposed rules and Uncontrolled users who did not. Controlled users consistently used less cannabis and had fewer problems.
Did legalization change how people use cannabis?
Some self-regulation improved (less use at work/school and while driving), but the ability to stop using cannabis decreased during the transition to legal adult use.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-06894APA
Lankenau, Stephen E; Ataiants, Janna; Prince, Mark; Fedorova, Ekaterina; Conn, Bridgid M; Ansell, Emily; Wong, Carolyn F. (2025). Controlled Use of Cannabis Among Young Adults in Los Angeles Across Changes in Cannabis Policies.. International journal of mental health and addiction. https://doi.org/10.1007/s11469-025-01608-w
MLA
Lankenau, Stephen E, et al. "Controlled Use of Cannabis Among Young Adults in Los Angeles Across Changes in Cannabis Policies.." International journal of mental health and addiction, 2025. https://doi.org/10.1007/s11469-025-01608-w
RethinkTHC
RethinkTHC Research Database. "Controlled Use of Cannabis Among Young Adults in Los Angeles..." RTHC-06894. Retrieved from https://rethinkthc.com/research/lankenau-2025-controlled-use-of-cannabis
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.