Controlled Use of Cannabis Among Young Adults in Los Angeles Across Changes in Cannabis Policies

The availability of cannabis has increased due to expanding legalization of cannabis across the USA. Controlled use of cannabis - rules by cannabis users that limit use - is a significant but understudied area in the present policy environment, particularly among young adults. A prospective Los Angeles-based cohort aged 18-26 who used cannabis in the past 90 days was assessed during eight survey waves across 9 years. Four discrete waves were analyzed: wave 1 (2014-2015/medical only policy, n = 366), wave 4 (2017-2018/transition to adult use policy, n = 275), wave 5 (2019-2020/adult use policy, n = 241), and wave 8 (2022-2023/adult use policy, n = 193). Five rules of controlled cannabis use were used as indicators in a latent class analysis. Two discrete latent classes - Controlled and Uncontrolled - emerged and became more distinct over time. The Uncontrolled class was a majority across all waves. Probabilities for two rules of controlled use - "no school/work" or "no driving" under the influence - increased overtime, and one rule - "stopping cannabis use" - decreased during the transition to legalized adult use. The Controlled class, which consistently practiced more rules, used less cannabis across all waves and had lower problematic cannabis use in waves 1, 4, and 5 compared to the Uncontrolled class.