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.
Prevention researchers, cannabis policymakers, and clinicians counseling young adult cannabis users.
Uncontrolled users were the majority across all 9 years
What the researchers 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.
Why it 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 numbers in context
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 the study worked
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.
What this study cannot 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.
How to read the evidence
Prospective cohort spanning a natural policy experiment provides strong longitudinal evidence, though attrition and single-city sample add limitations.
When this study was published
2025 publication analyzing 9 years of data (2014-2023) spanning cannabis policy transitions.
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.
Questions still open
- 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?
Common questions
Do cannabis users set rules for themselves?
Did legalization change how people use cannabis?
Read the original research
Controlled Use of Cannabis Among Young Adults in Los Angeles Across Changes in Cannabis Policies.
International journal of mental health and addiction
Citation
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