The risks and consequences of marijuana use for young adults.


  • Millions of teenagers in the United States use marijuana.
  • “Weed” may be the only emotional relief, albeit temporary, some teens can find.
  • Young people who are depressed are more likely to use marijuana, but it can make their depression worse.
  • The adult SUD and overdose crisis has its roots in teen and young adult use that targets and changes brains.

Child and adolescent psychiatrist Sarah Y. Vinson says some adolescents use marijuana because it’s the only “medicine” they can access. For some teens, marijuana is to emotional pain as acetaminophen is to physical pain. A major reason for this lies in the difficulty of obtaining adequate (or any) mental health care and/or medications for adolescents.

According to Vinson, chair of the psychiatry department at the Morehouse School of Medicine in Atlanta, “The reality for the poor traumatized kids I treat, and their parents and caregivers, is marijuana is a whole lot more accessible than high-quality, trauma-informed, culturally and structurally sensitive mental health care.”

She adds, “Marijuana is culturally sanctioned as a treatment for anxiety, depression, boredom, and a range of other psychiatric problems. Cannabis had been proposed as a treatment for most of the DSM and is the only treatment most of my patients can get regardless of whether it is safe or effective for any of these problems.”

I asked child and adolescent psychiatry and addiction experts Vinson and Marc Potenza about the consequences of teen use of marijuana, and both said the impact of cannabis on the developing brains and behavior of young people is a special concern.

According to Potenza, the Steven M Southwick Professor in the Yale Child Study Center and of Neuroscience; and director of the Yale Program for Research on Impulsivity and Impulse Control Disorders:

“Increasing knowledge about the harmful effects of alcohol may be decreasing alcohol consumption among some younger groups. Cannabis legalization has been accompanied by greater social acceptance of cannabis use, and these perceptions seem prominent among younger individuals. We see impacts on mood, psychiatric illness, increases in risky behaviors like unprotected sex, gambling, other drug use and driving under the influence of cannabis, THC, and or other drugs or alcohol.”

A recent study at Columbia found casual teenage use of marijuana increased risks for depression and suicidal behavior, as well as problem behaviors such as truancy, poor grades, and trouble with law enforcement. The researchers found that about 2.5 million teens were casual users. Casual users were up to 2.5 times more likely than non-users to have behavioral and mental health problems.

Facts on Teenage Weed Use

In 2022, 1.2 million adolescents ages 12-17 began using marijuana for the first time. According to the Substance Abuse and Mental Health Services Administration (SAMHSA), 6.4% of 12-17-year-olds (4.3 million people) used marijuana in the past month in 2022.

It’s also important to note that, in 2017, among adolescents aged 12-17 who used marijuana, 22% were depressed. A psychiatric disorder, particularly depression, also may increase the risk of marijuana abuse. According to SAMHSA, some adolescents (5%) had marijuana use disorder in 2022, which means they experienced adverse consequences of their drug use and yet couldn’t give the drug up.

How Marijuana Is Used Is Changing

Adolescents aged 12-17 used various means to ingest marijuana in 2022; the most popular was smoking (77%), followed by vaping (60%). (Some teens used multiple routes but chose the route with the greatest dose of THC delivered to the brain in the shortest time.) Overall, there’s not much difference between smoking and vaping, as inhalation is highly addicting—pharmacologically, like intravenous injection. Also popular was eating or drinking the drug (36%) or using dabbing waxes and concentrates (23%). Some adolescent users applied marijuana in a lotion, cream, or skin patch or used drops, lozenges, strips, and other means of administration.

Reducing Risk for Psychosis From Marijuana

It is known that marijuana use may lead to psychiatric issues and even psychosis. In an article by Benedikt Fischer and colleagues, the authors explored key issues linked to an increased risk for a psychotic break in adolescents who use marijuana. For example, early use of marijuana (at age 16 or younger) was a risk for psychosis and thus should be avoided. They also noted that high-potency marijuana increases the risk of psychosis and should be avoided by adolescents. (However, teenagers may perceive high-potency marijuana as even better than “regular” marijuana.)

Frequency of use was another risk factor for psychosis, such as weekly or daily use, with those using the drug daily at elevated risk for serious psychiatric problems such as psychosis. In addition, individuals who use other addictive substances in addition to marijuana, such as tobacco, alcohol, and illegal drugs, have a greater risk for psychosis, as well as a worse outcome, such as more frequent treatment relapses or worse cognitive symptoms.

Individuals with traumatic events in their past risk psychosis with marijuana. There is also a genetic component; if biologically related family members became psychotic after marijuana use, this may mean adolescents are at risk and likely should avoid the drug altogether.

Sometimes, marijuana affects how well psychiatric treatment drugs work; for example, individuals who receive antipsychotic medications may find their medication’s efficacy reduced when they use marijuana.

Adolescent Marijuana Users May Become Lifelong Consumers

Some purveyors of marijuana perceive adolescents as highly attractive consumers. “It shouldn’t surprise us THC is sold as gummy bears or ‘Krondike’ bars, or that vaping fluids with flavors like pineapple or mango come in thinly disguised packages that attract young people,” says Deepak Cyril D’Souza, Albert E. Kent Professor of Psychiatry at the Yale School of Medicine and a leading expert on the pharmacology of cannabinoids. “The idea is if you have a young customer, you have a lifelong customer.”

Driving and Adolescent Weed Use

It’s illegal for anyone to drive under the influence of marijuana, although state laws vary considerably. The point is that some teenage marijuana users do drive under the influence. A 2017 study found that nearly half of adolescent drivers had driven a vehicle after using marijuana, and 1 in 8 (12.5%) reported driving under the influence of marijuana in the past month.

Teenagers may perceive driving under the influence of marijuana as safer than driving while intoxicated with alcohol; however, driving under the influence of any mood-impairing drug is dangerous. In addition, most adolescents are inexperienced drivers who need their mental acuity to decrease the risks of poor judgment causing car crashes. It is also important to avoid being a passenger in a car where the driver has ingested marijuana; individuals should refuse to enter a car in that situation. Admittedly, such a refusal may be difficult in the face of social pressure but it may be a life-saving choice.


The United States is confronting a public health crisis of substance use disorders and overdose deaths. We need to refocus and reenergize prevention and educational initiatives and support psychiatric treatment alternatives for youth. Addiction often begins with use in the teenage years, and 90% of all adults with substance use disorders began using alcohol, nicotine, or marijuana before age 18. Also, using any one substance (alcohol, nicotine, marijuana) significantly increases the likelihood of using the other two. A growing body of scientific evidence shows that even a one-year delay in drug use during adolescence can lower future trajectories of use for years to come. Brain researchers believe teenagers are extremely vulnerable because adolescent and young adult brains are still developing. Although marijuana is perceived as harmless by many, the dangers outlined in my prior post are amplified with much more dire consequences in youth.

Also note that there is some good news: A growing percentage of teens are using little or no alcohol, nicotine, marijuana, or other drugs. This approach should be encouraged for teens and young adults to help them reduce risks, develop to their full potential, and not join the adult SUD and overdose risk group. Even among less frequent users, we should encourage longer non-use periods. Lastly, improved mental health access for adolescents in the United States is urgently needed.



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