Dr. Nora Volkow, the Director of National Institute on Drug Abuse, acknowledged in 2021 “I was expecting that the use of marijuana among adolescents would go up and overall it hasn’t.”

A meta-analysis (a study design using the findings from several studies to form a single conclusion) found that legalization of adult use (recreational) cannabis did not increase adolescents’ cannabis use (1). In fact, many studies have shown a decrease in adolescent use in association with cannabis legalization for medical or adult use (2-4). Recent studies in both Washington (5) and Colorado (6), the first two states to legalize adult use cannabis, found no significant impact of adult use legalization on adolescent use. A recent study in JAMA Psychiatry (7) found that any use and frequent use of cannabis did not increase in 12-17 years old individuals and cannabis use disorder was lower in 2013-2016 (after adult use legalization) compared to before legalization. Similar findings were observed in individuals 12-20 years old between 2008-2017 (8).

As the first state to legalize cannabis in the U.S., adolescent use of cannabis in Colorado is particularly instructive. Colorado Healthy Kids Survey [(9), Fig 5 in (10)] showed that high schoolers reported past-30 day cannabis use decreased from 22.7% in 2005 to 22.0% in 2011 and to 20.6% in 2019 (11). Using different survey methodology, the CDC’s Youth Risk Behavior Surveillance (YRBS) found 22% of Colorado high schoolers reporting past-30 day use immediately pre-legalization in 2011 and 20.1% in 2019 (10). Notably, the past-30 day use in Colorado high school students was 3-4% higher than U.S. high school students in 2003 through 2009 (using YRBS data) but has been persistently lower than U.S. high school students from 2011 through 2019.

References

1. Melchior M, Nakamura A, Bolze C, Hausfater F, El Khoury F, Mary-Krause M, Azevedo Da Silva M. Does liberalisation of cannabis policy influence levels of use in adolescents and young adults? A systematic review and meta-analysis. BMJ Open 2019; 9 (7), e025880.

2. Anderson DM, Hansen B, Rees DI, Sabia JJ. Association of Marijuana Laws With Teen Marijuana Use: New Estimates From the Youth Risk Behavior Surveys. JAMA Pediatr 2019; 173 (9), 879-881.

3. Coley RL, Hawkins SS, Ghiani M, Kruzik C, Baum CF. A quasi-experimental evaluation of marijuana policies and youth marijuana use. Am J Drug Alcohol Abuse 2019; 45 (3), 292-303.

4. Dilley JA, Richardson SM, Kilmer B, Pacula RL, Segawa MB, Cerda M. Prevalence of Cannabis Use in Youths After Legalization in Washington State. JAMA Pediatr 2019; 173 (2), 192-193.

5. Midgette G, Reuter P. Has Cannabis Use Among Youth Increased After Changes in Its Legal Status? A Commentary on Use of Monitoring the Future for Analyses of Changes in State Cannabis Laws. Prev Sci 2020; 21 (1), 137-145.

6. Brooks-Russell A, Ma M, Levinson AH, Kattari L, Kirchner T, Anderson Goodell EM, Johnson RM. Adolescent Marijuana Use, Marijuana-Related Perceptions, and Use of Other Substances Before and After Initiation of Retail Marijuana Sales in Colorado (2013-2015). Prev Sci 2019; 20 (2), 185-193.

7. Cerda M, Mauro C, Hamilton A, Levy NS, Santaella-Tenorio J, Hasin D, Wall MM, Keyes KM, Martins SS. Association Between Recreational Marijuana Legalization in the United States and Changes in Marijuana Use and Cannabis Use Disorder From 2008 to 2016. JAMA Psychiatry 2020; 77 (2), 165-171.

8. Martins SS, Segura LE, Levy NS, Mauro PM, Mauro CM, Philbin MM, Hasin DS. Racial and Ethnic Differences in Cannabis Use Following Legalization in US States With Medical Cannabis Laws. JAMA Netw Open 2021; 4 (9).

9. School CDoECCfH. Healthy Kids Colorado Survey Report, 2011. https://www.cde.state.co.us/healthandwellness/2011hkcsstatereport (accessed Feb 21, 2021).

10. Colorado Monitoring Health Concerns Related to Marijuana. Healthy Kids Colorado Survey (HKCS) data. 2021. https://marijuanahealthinfo.colorado.gov/health-data/healthy-kids-colorado-survey-hkcs-data (accessed Feb 21, 2021 2021).

11. Center for Disease Control and Prevention. Youth Risk Behavior Surveillance (YRBS). 2021. https://nccd.cdc.gov/Youthonline/App/Results.aspx?LID=CO Feb 21, 2021).