Partnership to End Addiction opposes the legalization of marijuana for recreational use because it will increase access to and use of the drug among adolescents. Marijuana is an addictive drug that can interfere with brain development and exacerbate mental health conditions. The risks of marijuana use have been demonstrated through clinical and epidemiological research and the concerns about these health risks and the adverse consequences of legalization have been consistently voiced by national medical societies (e.g., American Medical Association, American Society of Addiction Medicine, American Psychiatric Association and the American Academy of Pediatrics).
Because legalizing marijuana is expected to increase the number of people who use the drug, it is also likely to increase the number of people who develop a marijuana use disorder. The addiction treatment system does not have the resources to treat everyone who currently needs care and is not prepared to handle an increase in patient demand.
Instead of legalization, Partnership to End Addiction supports keeping marijuana illegal but decriminalizing personal use (see our accompanying position statement). Decriminalization is a public health approach that prioritizes treatment over incarceration and eliminates commercial incentives to promote marijuana use.
When used regularly during adolescence and early adulthood, a period of active brain development, marijuana can alter the structure and function of the brain, impairing learning and memory, and increasing the risk of addiction and psychosis. Although there is conflicting research and direct causation remains unclear, the bulk of evidence suggests that teens who use marijuana are at risk for cognitive impairment. Early and regular use during adolescence is associated with lower IQ later in adulthood and with decreased activity and/or connectivity in the areas of the brain related to executive function, learning and memory. Whether cognitive deficits are reversible is not completely clear. Early initiation and regular use are also associated with greater likelihood of developing a marijuana use disorder, which occurs in roughly one in six adolescent users – a rate that is nearly double that found among adult-onset users. Early initiation and regular use of marijuana also confers a higher risk for psychosis, especially among those predisposed to mental health problems. In addition to the health risks, adolescent marijuana use is associated with reduced educational attainment and increased likelihood of dropping out of high school.
Unfortunately, regular or heavy use is the norm among young marijuana users, a pattern unlikely to be improved by legalization. National survey data suggest that on average, high school students who currently use marijuana use it 2 or 3 days per week.
Approximately 9% of adults who use marijuana become addicted to it; this number may rise as levels of THC in marijuana increase. Regular marijuana use poses additional health risks, including cognitive and respiratory problems. Marijuana use can also exacerbate pre-existing mental health and medical problems and other substance use disorders.
Marijuana use also poses a risk to drivers and others on the road. Marijuana is the illicit drug most frequently reported in connection with impaired driving and motor vehicle accidents, including fatal accidents. Following alcohol, cannabis is the second most commonly detected substance in drivers who were fatally injured in car crashes. There is evidence that the cumulative effects of marijuana and alcohol when used together cause greater impairment to driving than either substance alone.
The very act of legalizing marijuana sends a message that the drug is safe and acceptable to use. This shift in cultural norms puts adolescents, in particular, at risk. Legalizing marijuana for adult recreational use is expected to decrease teens’ perception of the harms of marijuana. Data from three decades of survey research indicate that decreased perceptions of harm are strongly associated with increased rates of adolescent use.
Legalization will inevitably lead to the growth of a commercial marijuana industry whose business model will be to promote marijuana use. The tobacco and alcohol industries provide an illustrative example of how businesses that profit from addictive substances put the public’s health at risk. Through innovations in product development, marketing and lobbying, the tobacco industry made its product more addictive and dramatically increased its consumer base in a relatively short period of time. The nascent marijuana industry has already begun implementing tobacco’s successful strategies. The alcohol industry garners roughly half of its profits from under age and excessive drinking, both of which are injurious to public health. The growing marijuana industry will similarly be incentivized to promote underage and heavy use. In Colorado, where recreational marijuana use is legal, 87% of the profits come from people who use the drug five to seven days per week. People who begin using marijuana as teens are much more likely to become the heavy users who drive profits, so a marijuana industry would need to market to teens in order to generate the greatest profits.
States that legalize marijuana will likely adopt minimum age laws as a way to deter teen use; however, such laws are not very effective at keeping substances out of the hands of teens. Because teens’ primary sources of marijuana are their friends and family, if it is legal for adults, teens will have greater access to it, and greater access is associated with greater use. Alcohol is by far the most commonly used substance among teens, despite minimum legal drinking age restrictions.
Public health measures can help to reduce teen substance use. For example, there is reason to believe that the same strategies that have reduced smoking would also reduce marijuana use: strongly enforcing minimum purchase age laws; setting very high sales and excise taxes; imposing environmental use bans; prohibiting advertising, marketing and placement in entertainment media; and implementing sustained public awareness campaigns. All of these policies working together can have a positive impact on public health.
However, discussions about legalizing marijuana fail to take into account the substantial investment needed to adequately regulate the drug and prevent adolescent use. States that have legalized marijuana use to date are imposing only modest taxes (relative to cigarette taxes), which are insufficient to keep prices high enough to deter adolescent use, and so far are failing to make adequate investments in other public health efforts.
Currently, only one in 10 people with alcohol or drug addiction receive treatment. In states where marijuana is legalized, we can expect more people to use the drug and consequently develop a marijuana use disorder. The problem is especially concerning for adolescents; marijuana is the primary drug used by most teens admitted to addiction treatment programs. Increasing the number of people with marijuana problems will place additional demands on a treatment system that is already severely under-resourced; as a result, a greater percentage of people who need treatment will not receive it. It is incumbent on states that are considering legalizing marijuana to commit resources to offer effective prevention and treatment services for those who are at risk of or develop a marijuana use disorder.