What You Should Know About Marijuana Use in the United States

Given the evolving research on marijuana and mental illnesses—and the potential impacts of the shifting landscape of marijuana-related policy and legislation in the United States—psychiatrists must remain informed about how marijuana use affects mental health.

Perhaps most importantly, although occasional (that is, neither regular nor heavy) marijuana use may be of little consequence to healthy adults, use among adolescents is a serious concern. Adolescents who regularly use marijuana are at greater risk of amotivation, reduced academic performance, lower educational attainment, and potentially even school dropout. Marijuana use in adolescents also can have negative effects on IQ and increase the risk of cannabis dependence and other drug use.

There are at least three issues that further substantiate the concern about adolescent marijuana use.

Studies also show that marijuana use has complex connections with a number of psychiatric illnesses, including mood and anxiety disorders, other substance use disorders, and particularly psychotic disorders. Growing evidence strongly suggests that marijuana use (especially heavier use in adolescence) is an independent risk factor for, or a component cause of, schizophrenia and other psychotic disorders. There is also convincing evidence that marijuana use before the onset of any psychotic symptoms hastens the onset of psychosis among those who do develop a psychotic disorder, and marijuana use during the early course of psychotic disorders is associated with a number of poorer outcomes.

From a policy perspective, psychiatrists should be familiar with the evolving movement around decriminalization (that is, reducing or removing criminal penalties) of marijuana possession and use, and even legalization (that is, removing criminal penalties and establishing a system of taxation and regulation of production, processing, and distribution) of both medical marijuana and recreational marijuana. Many more state legislatures will be addressing these issues, and we should be following the story and contributing to the political discourse and debate in a balanced, objective, and research-informed fashion.

Aside from decriminalization and legalization of recreational marijuana, about half of the states (and the list will undoubtedly grow) have already passed medical marijuana legislation. Psychiatrists and other physicians will increasingly be approached by patients with questions about medical marijuana, if not direct requests for qualification letters.

Some people who use marijuana (especially in adolescence) will develop addiction. More research is needed to determine the factors that predispose to and protect from addiction in the context of initial or escalating drug intake. Perhaps of greatest importance for psychiatrists is the evaluation and management of cannabis use disorder; specifically, the typical withdrawal symptoms that can occur, and the best-supported psychosocial (and potentially emerging pharmacological) approaches to treatment. Although prevention efforts are typically carried out in school-, family-, and community-based venues, psychiatrists may play a role in communicating the short- and long-term risks associated with cannabis use.

Another topic that psychiatrists should remain informed about is synthetic cannabinoids. Although these synthetic chemicals bear little resemblance to marijuana, many who use these potent and potentially very dangerous chemicals consider them to be somehow comparable to marijuana derived from the Cannabis sativa plant. A growing body of case literature and observational studies indicates that synthetic cannabinoid ingestion can bring about prominent and sometimes very serious acute psychiatric and medical manifestations. We have much to learn about the evaluation, management, and prevention of synthetic cannabinoid use.

As we look to the future, health professionals should be prepared for changes in laws pertaining to legalization, driving under the influence, drug-free workplace policies, and medical marijuana programs. Health professionals should also stay tuned for information on potential therapeutic uses of CBD for several health conditions, possibly including psychotic disorders. ■