Estimating the effects of legalizing recreational cannabis on newly incident cannabis use

Abstract

Liberalized state-level recreational cannabis policies in the United States (US) fostered important policy evaluations with a focus on epidemiological parameters such as proportions [e.g., active cannabis use prevalence; cannabis use disorder (CUD) prevalence]. This cannabis policy evaluation project adds novel evidence on a neglected parameter–namely, estimated occurrence of newly incident cannabis use for underage (<21 years) versus older adults. The project’s study populations were specified to yield nationally representative estimates for all 51 major US jurisdictions, with probability sample totals of 819,543 non-institutionalized US civilian residents between 2008 and 2019. Standardized items to measure cannabis onsets are from audio computer-assisted self-interviews. Policy effect estimates are from event study difference-in-difference (DiD) models that allow for causal inference when policy implementation is staggered. The evidence indicates no policy-associated changes in the occurrence of newly incident cannabis onsets for underage persons, but an increased occurrence of newly onset cannabis use among older adults (i.e., >21 years). We offer a tentative conclusion of public health importance: Legalized cannabis retail sales might be followed by the increased occurrence of cannabis onsets for older adults, but not for underage persons who cannot buy cannabis products in a retail outlet. Cannabis policy research does not yet qualify as a mature science. We argue that modeling newly incident cannabis use might be more informative than the modeling of prevalences when evaluating policy effects and provide evidence of the advantages of the event study model over regression methods that seek to adjust for confounding factors.

Exploring the Potential of Cannabinoid Nanodelivery Systems for CNS Disorders

“…Due to the process of legalization, the use of marijuana in the last year of young adults aged 19–30 years increased significantly, compared with five and ten years earlier, reaching historical highs [ 13 , 14 , 15 ]. Concomitantly with the increased use of cannabinoid, rapid assays for on-site cannabinoids detection in oral fluids have been developed [ 16 , 17 ].…”

The clouded debate: A systematic review of comparative longitudinal studies examining the impact of recreational cannabis legalization on key public health outcomes

“…As well, the results yielded from current studies refer to past-month use, which is an outcome that cannot differentiate between adult populations that are occasionally experimenting with cannabis from populations that are transitioning from occasional use to heavy use or cannabis use disorder. Early work by Montgomery et al ( 53 ) has discerned potential increases in newly onset cannabis use in the adult population following RML, but not the underage population, suggesting heightened experimenting among adults who may not have otherwise tried cannabis, however these findings should be replicated before deemed as conclusive ( 53 ).…”

Effects of cannabis legalization on the use of cannabis and other substances

“…Lower risk perception was significantly associated with higher use among both adolescents and young adults with associations becoming stronger after legalization [12 ▪ ]. However, another found no effect of RCL on the occurrence of newly incident cannabis onsets for underage persons (<21 years), either after the legalization date ( P = 0.27) or the effective date ( P = 0.53) [13 ▪ ]. This is consistent with a study using national and state data from the Youth Risk Behavior Survey (YRBS) in 1993 to 2017, which found no association between both RCL and MCL with current or frequent cannabis use among high-school students [14].…”

“…Two studies used data of 2008 to 2019 waves from the National Surveys on Drug Use and Health (NSDUH) [12 ▪ ,13 ▪ ] in all US states. One found increased past-month cannabis use prevalence for both adolescents (age 12–17) and young adults (18–25) along with a declined perception of risk of harm from use among young adults, following RCL.…”