Marijuana Poly-Substance Use Gateway Companion Drug

Frequency of adolescent cannabis smoking and vaping in the United States: Trends, disparities and concurrent substance use, 2017–19

19 May 2022


Past 30-day frequent cannabis use with vaping and occasional use with vaping rose from 2017 to 2019. Past 30-day frequent and occasional cannabis use without vaping declined. Certain groups, such as Hispanic/Latino or lower socio-economic status adolescents, experienced particularly notable increases in frequent cannabis use with vaping (e.g. prevalence among Hispanic/Latino adolescents). Adolescents who reported smoking and vaping nicotine, and 10+ occasions of binge drinking, were 42.28 [95% confidence interval (CI) = 33.14–53.93] and 10.09 (95% CI = 4.51–22.53) times more likely to report past 30-day cannabis use with vaping, respectively, compared with no use.


Cannabis use without vaping appears to be declining among adolescents in the United States, while cannabis use with vaping is accelerating; frequent cannabis vaping is especially increasing, with consistent increases across almost all adolescent demographic groups. Cannabis use among US adolescents remains highly associated with other substance use.

Understanding Opioid Use Disorder (OUD) using tree-based classifiers


We developed a method to identify adults likely to develop Opioid Use Disorder.•

Early initiation of marijuana is a dominant predictor of Opioid Use Disorder.•

The method considers demographic, socioeconomic, and health related features.•

Mining public domain datasets can aid in understanding addiction disorders.

Association between medical cannabis laws and opioid overdose mortality has reversed over time

June 10, 2019


Medical cannabis has been touted as a solution to the US opioid overdose crisis since Bachhuber et al. [M. A. Bachhuber, B. Saloner, C. O. Cunningham, C. L. Barry, JAMA Intern. Med. 174, 1668–1673] found that from 1999 to 2010 states with medical cannabis laws experienced slower increases in opioid analgesic overdose mortality. That research received substantial attention in the scientific literature and popular press and served as a talking point for the cannabis industry and its advocates, despite caveats from the authors and others to exercise caution when using ecological correlations to draw causal, individual-level conclusions. In this study, we used the same methods to extend Bachhuber et al.’s analysis through 2017. Not only did findings from the original analysis not hold over the longer period, but the association between state medical cannabis laws and opioid overdose mortality reversed direction from −21% to +23% and remained positive after accounting for recreational cannabis laws. We also uncovered no evidence that either broader (recreational) or more restrictive (low-tetrahydrocannabinol) cannabis laws were associated with changes in opioid overdose mortality. We find it unlikely that medical cannabis—used by about 2.5% of the US population—has exerted large conflicting effects on opioid overdose mortality. A more plausible interpretation is that this association is spurious. Moreover, if such relationships do exist, they cannot be rigorously discerned with aggregate data. Research into therapeutic potential of cannabis should continue, but the claim that enacting medical cannabis laws will reduce opioid overdose death should be met with skepticism.

How can marijuana be addictive and a gateway drug at the same time?

Christine L. Miller, Ph.D.

This can happen because the pathways to addiction with different drugs share common features:

The common mechanism via dopamine is also the case for the effect of THC:

When marijuana can no longer excite the common pathway as the drug’s receptors become desensitized, the user switches to a new drug. The addiction to marijuana is no longer satisfying.
Research has confirmed that marijuana acts as a gateway drug for many users:


Escalation of Drug Use in Early-Onset Cannabis Users vs Co-twin Controls

January 22, 2003

Results  Individuals who used cannabis by age 17 years had odds of other drug use, alcohol dependence, and drug abuse/dependence that were 2.1 to 5.2 times higher than those of their co-twin, who did not use cannabis before age 17 years. Controlling for known risk factors (early-onset alcohol or tobacco use, parental conflict/separation, childhood sexual abuse, conduct disorder, major depression, and social anxiety) had only negligible effects on these results. These associations did not differ significantly between monozygotic and dizygotic twins.

Conclusions  Associations between early cannabis use and later drug use and abuse/dependence cannot solely be explained by common predisposing genetic or shared environmental factors. The association may arise from the effects of the peer and social context within which cannabis is used and obtained. In particular, early access to and use of cannabis may reduce perceived barriers against the use of other illegal drugs and provide access to these drugs.

Multi-directional pathways of tobacco and marijuana use, including comorbid use, among a population-based cohort of adolescents in Texas: A six-wave cross-lagged model

2021 Apr

Conclusions: This is the first study to longitudinally situate comorbid, past 30-day use of tobacco and marijuana and simultaneously examine bi-directional past 30-day use of these products for adolescents. Marijuana use more often and more strongly predicted subsequent tobacco use than the reverse, especially during middle adolescence (13-15 years old). Marijuana use should be considered when creating interventions that address adolescent e-cigarette use in the U.S.

Adolescent drug use initiation and transition into other drugs: A retrospective longitudinal examination across race/ethnicity


69% adolescent drug users initiated with marijuana and 27% with inhalants.•

About 40% of inhalant users transitioned to new drugs by year 8.•

About 70% to 80% other drug users transitioned to new drugs by year 8.•

There were racial/ethnic discrepancies in both drug use initiation and transition.