SynthesisBMJ open2019
Does liberalisation of cannabis policy influence levels of use in adolescents and young adults? A systematic review and meta-analysis.
Synthesis in BMJ open, 2019. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 50 papers, 2 of them syntheses that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
50 citing papers in PubMed, 2 syntheses or guidelines pooled it.
- Is legalization of recreational cannabis associated with levels of use and cannabis use disorder among youth in the United States? A rapid systematic review.European child & adolescent psychiatry · 2024Pooled it
- Impact evaluations of drug decriminalisation and legal regulation on drug use, health and social harms: a systematic review.BMJ open · 2020Pooled it
- A randomized pilot trial of a mobile phone-based brief intervention with personalized feedback and interactive text messaging to reduce driving after cannabis use and riding with a cannabis impaired driver.Journal of substance abuse treatment · 2022Trial
- How tax structures for retail cannabis shape cannabis use among youth and young adults: evidence from a volumetric choice experiment.The European journal of health economics : HEPAC : health economics in prevention and care · 2026Article
- Increase in Cannabis-Specific Hospital Admissions After Partial Legalization in Germany: A Nationwide Time-Series Analysis.Deutsches Arzteblatt international · 2026Observational
- Expected population prevalence following decriminalization of recreational use of cannabis in Sweden.Journal of cannabis research · 2026Article
- Cannabis and Derived Cannabis Use, Motives, and Consequences Among US Young Adults: Findings From a Cross-Sectional Mediation Study.Substance use & addiction journal · 2026Article
- A longitudinal mediated examination of legal, commercial, and individual determinants of cannabis and derived cannabis use behaviors and consequences among US young adults.Addictive behaviors · 2026Article
- Changes in psychosis-related emergency department and hospitalization rates among youth following cannabis legalization in Colorado.Drug and alcohol dependence · 2025Article
- Cannabis Marketing Strategies in the United States: A Descriptive Analysis of Four Prominent Companies.Substance use & addiction journal · 2025Article
- Differences in Online Descriptions and Marketing of Derived Intoxicating Cannabis Products.Journal of psychoactive drugs · 2025Article
- Post-legalization shifts in cannabis use among young adults in Georgia-A nationally representative study.Addiction (Abingdon, England) · 2025Article
- Unveiling the Complexities of Medications, Substance Abuse, and Plants for Recreational and Narcotic Purposes: An In-Depth Analysis.Pharmacy (Basel, Switzerland) · 2025Review
- Temporal Trends in Young Adult Cannabis and Tobacco Use in States with Different Cannabis Policies.Cannabis (Albuquerque, N.M.) · 2025Article
- Associations between cannabis risk perceptions and Delta-8 THC use among young adults.Journal of substance use · 2025Article
- Associations Between Cannabis Messaging and Derived Psychoactive Cannabis Product Perceptions, Use, and Use Intentions Among a Sample of US Young Adults.Substance use & misuse · 2025Article
- Evaluating Online Cannabis Health Information for Thai Breast Cancer Survivors Using the Quality Evaluation Scoring Tool (QUEST): Mixed Method Study.JMIR cancer · 2024Article
- Increasing lifetime and past 30-day marijuana use among middle school students regardless of recreational marijuana sales.Addictive behaviors · 2024Article
- Medicinal cannabis use among young adults during California's transition from legalized medical use to adult-use: a longitudinal analysis.The American journal of drug and alcohol abuse · 2024Article
- Cannabis reduction among adolescents as spillover from successful tobacco control.The International journal on drug policy · 2024Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
7 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
objectivesTo examine the effect of cannabis policy liberalisation (decriminalisation and legalisation) levels of use in adolescents and young adults.
designSystematic review and meta-analysis. INCLUSION CRITERIA: Included studies were conducted among individuals younger than 25 years and quantitatively assessing consequences of cannabis policy change. We excluded articles: (A) exclusively based on participants older than 25 years; (B) only reporting changes in perceptions of cannabis use; (C) not including at least two measures of cannabis use; (D) not including quantitative data; and (E) reviews, letters, opinions and policy papers. PubMed, PsycINFO, Embase and Web of Science were searched through 1 March 2018. DATA EXTRACTION AND SYNTHESIS: Two independent readers reviewed the eligibility of titles and abstracts and read eligible articles, and four authors assessed the risk of bias (Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies). Extracted data were meta-analysed. The protocol was registered with PROSPERO.
results3438 records were identified via search terms and four via citation lists; 2312 were retained after removal of duplicates, 99 were assessed for eligibility and 41 were included in our systematic review. 13 articles examined cannabis decriminalisation, 20 examined legalisation for medical purposes and 8 examined legalisation for recreational purposes. Findings regarding the consequences of cannabis decriminalisation or legalisation for medical purposes were too heterogeneous to be meta-analysed. Our systematic review and meta-analysis suggest a small increase in cannabis use among adolescents and young adults following legalisation of cannabis for recreational purposes (standardised mean difference of 0.03, 95% CI -0.01 to -0.07). Nevertheless, studies characterised by a very low/low risk of bias showed no evidence of changes in cannabis use following policy modifications.
conclusionsCannabis policy liberalisation does not appear to result in significant changes in youths' use, with the possible exception of legalisation for recreational purposes that requires monitoring. TRIAL REGISTRATION NUMBER: CRD42018083950.
Indexed as
Identifiers
What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.