Published summary: 2026-03-07
Where the evidence converges
Meta-analysis of 220,362 adolescents across 47 countries found 7% global cannabis prevalence, with boys and high-income countries showing higher rates and Latin America leading regionally
Moderate evidence · 6 studies
Based on limited number of strong-evidence studies.
20-year analysis of German addiction treatment data found cannabis-related admissions nearly tripled (7
Moderate evidence · 6 studies
Based on limited number of strong-evidence studies.
Where questions remain
National case-control study found cannabis use associated with 83% increased odds of suicide death, independent of alcohol
Moderate evidence · 10 studies
Cross-sectional case-control design prevents causal conclusions. Controls were from a general population survey while cases were suicide decedents, creating potential selection bias. Mental health con
Survey of 1,113 Polish adults found 81% support medical cannabis and 84% would try it, but only 4
Moderate evidence · 10 studies
Online survey may underrepresent older adults and rural populations despite nationally representative sampling. Self-reported attitudes may not reflect behavior. Cross-sectional design captures one ti
Analysis of 496 cannabis users in São Paulo identified four distinct profiles, with about 30% in high-risk categories characterized by early onset, frequent use, and polydrug patterns
Moderate evidence · 10 studies
Cross-sectional design limits causal inference. Self-reported substance use. São Paulo sample may not represent all of Brazil. Latent class analysis findings are sample-dependent and may not replicate
Study of 95,645 Northern California teens found cannabis retail bans associated with lower psychotic disorder rates, and greater retail density linked to higher rates of anxiety and depressive disorders
Moderate evidence · 10 studies
Cross-sectional design cannot establish causation. Cannabis use itself was not measured, only retail availability and mental health outcomes. Residual confounding by neighborhood socioeconomic factors
Research gaps
- Only 0 randomized controlled trials exist out of 38 studies — most evidence is observational or from reviews.
- No meta-analyses have been published on this specific topic, limiting the ability to draw pooled quantitative conclusions.
- Sex-specific differences in this area remain understudied.
Key studies
Teen Cannabis Use Has Dropped Since 1999 — But Girls Now Use More Than Boys
The historic gender reversal challenges decades of assumptions about male-predominant cannabis use and demands updated prevention approaches that address why girls are now using more.
The Legal Loophole That Put THC Drinks in Every State — Including Where Marijuana Is Illegal
Intoxicating THC beverages are now legally sold in states that specifically chose to ban marijuana — exploiting a federal loophole that lawmakers didn't anticipate when legalizing agricultural hemp.
Living Near a Cannabis Store Linked to 12% More Cannabis ER Visits
This is among the strongest evidence that cannabis retail density directly affects health harms. It suggests policymakers can reduce cannabis-related ER visits by limiting store density or prohibiting stores in certain areas — a practical, implementable public health tool.
7% of Adolescents Worldwide Used Cannabis, With Boys and the Americas Leading Rates
This is one of the most comprehensive global assessments of adolescent cannabis use, filling a critical gap in data from low- and middle-income countries that have been underrepresented in previous research.
Cannabis Treatment Demand Nearly Tripled in Germany Over 20 Years, With Patients Getting Older
With Germany legalizing cannabis in 2024, understanding pre-legalization treatment demand trends is essential for planning services. The aging treatment population suggests current programs designed for young users may be inadequate.
Most Teens Heard About the Vaping Lung Injury Outbreak — But Most Blamed Nicotine, Not Cannabis
The EVALI crisis killed 68 people, primarily from vitamin E acetate in illicit cannabis vapes. But the public health message was garbled — most teens think nicotine vapes were the problem. This misinformation may cause teens to avoid less-harmful nicotine vapes while underestimating risks of illicit
How the research developed
2020–present
38 studies published. Includes 6 strong-evidence studies.
How this summary was assembled
This consensus synthesizes 38 peer-reviewed studies: 29 observational studies (76%), 1 reviews (3%), 8 other study types (21%). Studies span from the earliest available research through 2025. Evidence strength ratings reflect study design, sample size, and replication across multiple research groups.
These counts describe the source summary at publication. They may differ from the current library.