As cannabis becomes more widespread in society and in many ways culturally accepted, many people are keen to point out the impact on youth. While you may think that adults should be able to use cannabis if they want to or if they have a medical condition it can help with, some people forget the impact this could have on the most vulnerable people in our society.
In fact, the risks of cannabis to youth are one of the most common arguments for keeping the current approach in terms of legality.
As part of our series on the Best Arguments for and Against Cannabis, we’re taking a look at the argument that the risks of cannabis to youth are a good reason to maintain the current prohibition.
Summary: Should We Ban Cannabis Because It Is Dangerous for Youth?
Yes…
- People who use cannabis in youth are more likely to develop depression and attempt suicide. It has a negative effect on brain development.
- There is evidence that legalizing cannabis increases cannabis use disorder among youths.
- Legalizing cannabis exposes more youth to the risks, so it is not a good policy proposal.
No…
- The evidence on youth use before and after legalization is mixed – some studies also show no increase in usage rates.
- Youth use cannabis even when it is banned. In fact, having no control of the market may make it worse, since street dealers don’t check ID.
- Legalization that minimizes black market sales and ensures safe products is the best way to protect both youth and adults.
The Risks of Cannabis to Young People
There are many potential areas of risk for young people who use cannabis. For example, there are risks associated with any smoking. However, we will focus on psychological and developmental effects on young people here. We have a post in this series addressing more general risks of cannabis if you want more information on that.
Mental health impacts of early cannabis use have been investigated by many studies. Although results can vary, when you look at all of the evidence together the picture is clear. One systematic review and meta-analysis looked at 11 studies in detail, with a total of 23,317 participants across all studies. After the authors combined the results, they found a few statistically significant differences between people who used cannabis in young adulthood vs. non-users.
People who used cannabis in young adulthood were:
- 37% more likely to develop depression
- 50% more likely to have suicidal ideation
- Almost 3.5-fold more likely to attempt suicide
This analysis did use the results for the highest-frequency cannabis users in the group. For example, if the study included once a month users and daily users, the authors took the results for the daily users. However, other research has found similar results looking at people with “non-disordered” cannabis use. This means use in the past year but without meeting the definition of cannabis use disorder.
Some studies have also found a negative impact of THC on adolescent brain development. In particular, data shows that people who started smoking cannabis in adolescence have impaired neural connectivity in regions of the brain responsible for alertness, self-conscious awareness, learning, memory, executive control, and in the subcortical networks that process habits and routines. The authors of the review write:
The impairments in brain connectivity associated with exposure to marijuana in adolescence are consistent with preclinical findings indicating that the cannabinoid system plays a prominent role in synapse formation during brain development.
Finally, there is evidence that people who start using cannabis in adolescence have an increased risk of addiction compared to those who start using later.
Legalizing Cannabis Exposes Youth to These Risks
Legalizing cannabis will make this whole situation worse if it makes youth more likely to smoke weed. There is certainly evidence of this.
Smart Approaches to Marijuana pointed out that based on the 2021/2022 National Survey on Drug Use and Health, of the 10 states with the highest past-year cannabis use at ages 12 to 17, 9 had legalized cannabis. If you look at states with the highest past-month use, 8 out of 10 had legalized.
However, it must be said that this isn’t necessarily the best way to investigate this issue. These states could have had also high youth use even before legalization. It is not clear from this “top 10” approach whether this is true. Other research has investigated this in a more comprehensive way.
One study used evidence from the same survey from 2008 to 2016. They found that cannabis use disorder increased from 2.18% to 2.72% after the legalization of recreational cannabis, a 25% greater increase than in states that didn’t legalize. Of those who’d used cannabis in the past year (in the same age group), cannabis use disorder increased from 22.8% to 27.2%.
Other research looking at young adults using the same survey also found an increase, with past-month cannabis use going from 21% to 25% after recreational legalization. A proxy measure of cannabis use disorder also showed an increase after legalization. However, in this study the increases were only detected for young adults not in college and those aged 21 to 23.
Overall, if legalization increases the likelihood youth will use cannabis, then more youth will open themselves up to the risks in the previous section.
Counterpoint: The Evidence on Legalization Increasing Youth Use is Mixed
It’s important to note the limitations of the evidence cited above. The study on young adults only found an increase in use for specific subgroups (i.e. non-college adults) and on specific measures. Notably, frequent use did not change after recreational legalization.
In the other study, the increase in cannabis use disorder risk was relatively small, and again there was no corresponding increase in other measures. For instance, both past-month use overall and frequent use among 12 to 17 year olds did not change following legalization. Many of these arguments depend on cherry-picking one or two results from papers that do not show a uniform trend.
Moreover, other research shows different results. This study used data from the Monitoring the Future survey from 2010 to 2015 to investigate the same question, looking at Colorado and Washington in particular. The results are decidedly mixed. In Washington, there was an increase in use among 8th and 10th graders after legalization (2% and 4.1%, respectively). But there was no difference among Washington 12th graders and no differences at all in Colorado.
Even though it might seem obvious that legalization would increase use among youth, this is not clearly borne out by the data. The picture is actually more complicated than you might expect.
Counterpoint: Risks to Youth are a Reason to Legalize, Not Maintain Prohibition
Although the evidence on what happens to youth cannabis use after legalization is mixed, one point is unavoidable. There are no age restrictions for buying cannabis in a prohibition system, but there are in a legal system.
If we’re concerned about youth getting access to cannabis, the status quo is not something to shoot for. The dealer on the street corner is not checking IDs. Even worse, the cannabis itself has no guarantee of purity or safety. In contrast, a legal system allows age restrictions on purchases. It institutes rules to make sure that the cannabis is actually safe.
Taking steps to control the black market is crucial for this to actually work, though. States that legalize should make sure that prices are competitive (minimizing taxes at first can be very helpful) and that there are at least 10 dispensaries per 100k residents. If the black market persists, legalizing will not help keep cannabis out of the hands of youth.
Our Take: The Status Quo Already Increases Risks for Youth
While the dangers of cannabis use for youth are important and should be a factor in any discussions around legalization, most arguments on this topic ignore a key point: the current system does not protect youth.
When the black market is the only market, there are no guardrails to protect youth, there are no age restrictions, and there is no control in general. But youth still use cannabis, and so any concern about risks to youth doesn’t justify keeping the status quo.
References
Barcott, B., & Whitney, B. (2022). ‘Opt-out’ towns are encouraging illegal marijuana sales. Leafly. https://leafly-cms-production.imgix.net/wp-content/uploads/2022/09/21143531/OptOutReport2022.pdf
About the source:
- Peer reviewed? No, a report from Leafly.
- Methodology: Used data from multiple sources to determine what percentage of cannabis sales took place in the black market vs. the state-legal market.
- Main results: States with more dispensaries per 100k residents generally capture more of the cannabis market with legal sales. “Opt-out” towns tend to reduce this number.
- Other notes: While this shows how to reduce the size of black markets, it’s important to note that there are still black markets even in “ideal” legal systems.
Cerdá, M., Mauro, C., Hamilton, A., Levy, N. S., Santaella-Tenorio, J., Hasin, D., Wall, M. M., Keyes, K. M., & Martins, S. S. (2020). Association between recreational marijuana legalization in the United States and changes in marijuana use and cannabis use disorder from 2008 to 2016. JAMA Psychiatry, 77(2), 165. https://doi.org/10.1001/jamapsychiatry.2019.3254
About the source:
- Peer reviewed? Yes, published in JAMA Psychiatry.
- Methodology: Used data from the National Survey on Drug Use and Health from 2008 to 2016 to look at the link between recreational cannabis legalization and changes in cannabis use, frequent use and cannabis use disorder (CUD).
- Sample size: 505,796 (149,383 aged 12 to 17).
- Main results: Past-year CUD increased from 2.18% to 2.72% among those aged 12 to 17 in states that had legalized cannabis, which was 25% higher than the increase in states that hadn’t legalized.
- Other notes: While CUD increased in adolescents, overall use or frequent use did not, and the authors urge caution in interpreting this result.
Cerdá, M., Wall, M., Feng, T., Keyes, K. M., Sarvet, A., Schulenberg, J., O’Malley, P. M., Pacula, R. L., Galea, S., & Hasin, D. S. (2017). Association of state recreational marijuana laws with adolescent marijuana use. JAMA Pediatrics, 171(2), 142. https://doi.org/10.1001/jamapediatrics.2016.3624
About the source:
- Peer reviewed? Yes, published in JAMA Pediatrics.
- Methodology: Used data from the Monitoring the Future survey to look at changes in past-month cannabis use before and after legalization in Washington and Colorado.
- Sample size: 253,902 eighth, tenth and twelfth grade students
- Main results: Cannabis use increased by 2% in eighth graders and 4.1% in tenth graders after legalization in Washington, with an overall decrease in states that did not legalize.
- Other notes: The study found no differences in Colorado. Additionally, Monitoring the Future selects specific schools and only surveys students who attend, which may impact how much the results can be generalized.
Chen, C.-Y., Storr, C. L., & Anthony, J. C. (2009). Early-onset drug use and risk for drug dependence problems. Addictive Behaviors, 34(3), 319–322. https://doi.org/10.1016/j.addbeh.2008.10.021
About the source:
- Peer reviewed? Yes, published in Addictive Behaviors.
- Methodology: Used evidence from the National Survey on Drug Use and Health from 2000 to 2002 to investigate the risk of developing drug key signs of drug dependence for “recent onset” users at the time of the survey.
- Sample size: 5,547 recent-onset cannabis users, including 4,049 adolescents (aged under 17), as well as users of other drugs.
- Main results: Adolescent-onset cannabis users were 3 times more likely than adult-onset users to develop clinical signs of dependence.
- Other notes: The study depends on self-reporting. However, there is no particular reason to expect it to be inaccurate.
Gobbi, G., Atkin, T., Zytynski, T., Wang, S., Askari, S., Boruff, J., Ware, M., Marmorstein, N., Cipriani, A., Dendukuri, N., & Mayo, N. (2019). Association of cannabis use in adolescence and risk of depression, anxiety, and suicidality in young adulthood. JAMA Psychiatry, 76(4), 426. https://doi.org/10.1001/jamapsychiatry.2018.4500
About the source:
- Peer reviewed? Yes, published in JAMA Psychiatry.
- Methodology: A systematic review of longitudinal and prospective studies looking at cannabis use before the age of 18 and the risk of developing depression as a young adult.
- Sample size: 11 studies with 23,317 individuals.
- Main results: People who used cannabis as minors were 37% more likely to develop depression, 50% more likely to have suicidal ideation and 3.46-times more likely to attempt suicide. There was no significant difference for anxiety.
- Other notes: It is difficult to establish causality from this analysis. Some studies didn’t control for other drug use, smoking and psychosocial factors that could be linked to both depression and early cannabis use. They also point out that they didn’t know the exact amount of cannabis used or how strong it was.
Kerr, D. C. R., Levy, N. S., Bae, H., Boustead, A. E., & Martins, S. S. (2023). Cannabis and alcohol use by U.S. young adults, 2008-2019: Changes in prevalence after recreational cannabis legalization. American Journal of Preventive Medicine. https://doi.org/10.1016/j.amepre.2023.06.009
About the source:
- Peer reviewed? Yes, published in the American Journal of Preventative Medicine.
- Methodology: Used data from the National Survey on Drug Use and Health for participants aged between 18 and 23 from 2008 to 2019. Researchers looked at frequent use, past-month use and a proxy for cannabis use disorder (CUD) for states with recreational cannabis legalization vs. those without it.
- Sample size: 123,162 college-age young adults.
- Main results: Past-month cannabis use increased from 21% to 25% and past year (proxy) CUD increased from 11% to 13% after recreational cannabis legalization. The changes were primarily seen in young adults not in college and who were 21 to 23 years old.
- Other notes: This study only found differences after legalization for adults who would be able to legally buy cannabis. Its relevance to the overall topic here is debatable.
Sultan, R. S., Zhang, A. W., Olfson, M., Kwizera, M. H., & Levin, F. R. (2023). Nondisordered cannabis use among US adolescents. JAMA Network Open, 6(5), Article e2311294. https://doi.org/10.1001/jamanetworkopen.2023.11294
About the source:
- Peer reviewed? Yes, published in JAMA Network Open.
- Methodology: Used data from the National Survey on Drug Use and Health from youth aged 12 to 17, split into non-users of cannabis, people who used but don’t have cannabis use disorder (CUD) or people with CUD. They compared these groups for adverse psychosocial events (e.g. major depressive episodes or suicidal ideation).
- Sample size: 68,263 adolescents.
- Main results: People with non disordered cannabis use were 2 to 4 times more likely to have an adverse psychosocial event compared to non-users, and people with CUD were even more likely to have experienced one.
- Other notes: This study was cross-sectional (at a single point in time), so it can’t show a causal relationship. The authors point out that anxiety often pre-dates substance use and the survey data doesn’t have information to let them analyze this possibility.
Volkow, N. D., Baler, R. D., Compton, W. M., & Weiss, S. R. B. (2014). Adverse health effects of marijuana use. New England Journal of Medicine, 370(23), 2219–2227. https://doi.org/10.1056/nejmra1402309
About the source:
- Peer reviewed? Yes, published in the New England Journal of Medicine.
- Methodology: A non-systematic review of the evidence on the adverse health effects of cannabis use.
- Main results: Long-term or heavy cannabis use has many negative effects, including addiction and increased risk of chronic psychosis disorders. Notably, it also reports a negative effect of THC on adolescent brain development.
- Other notes: This paper is likely biased in intent (i.e. listing adverse events, not “health consequences” or something neutral) and some studies it cites have been called into question. For example, a link between adolescent cannabis use and IQ declines is mentioned but this is likely due to other factors not controlled for in the original study.