Cannabis and the Teenage Brain

By Randall Dwenger, M.D.

In recent years, policies and attitudes regarding marijuana have been shifting, with more than 37 states permitting marijuana for medical purposes and over 20 states now legalizing cannabis for recreational use.  While we are adapting to the new normal of marijuana’s growing presence in our communities, the shift in perception that marijuana is now “safe” is alarming.  But for teens and young adults whose brains are still developing, there is no new news. The increase in availability, the increase in potency of cannabis products, and the increase in marketing efforts that appeal to teens all put youth and their developing brains at increased risk.

Cannabis Is a Big Business

The changes in marijuana laws have spawned huge growth in the businesses of cannabis. According to a report by New Frontier Data, a cannabis market research firm, legal cannabis sales in the United States reached $17.5 billion in 2020, a 46 percent increase from 2019. Some experts predict cannabis sales will grow to $41.5 billion by 2025. 

Two teens sitting outside on school steps having a conversation.

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The cannabis industry’s growth has been explosive in the Northeast.  In Connecticut, adult-use cannabis sales began in January 2023 and totaled $5 million.  By May, the value more than doubled.  As of June 2023, New Jersey legal marijuana sales reached $180 million. And in New York State, cannabis is expected to generate $4.2 billion in revenue annually. Of course, these are just the publicly reported sales figures. There has been a huge surge in illegal sales as well—from unregulated specialty shops and from vendors and dealers “on the streets.” In fact, New York City is home to over 1,400 unlicensed stores, with just four licensed retailers.

Ready Access and Omnipresent Marketing

It is no surprise that marijuana consumption is trending upward in the United States. There were approximately 28 million marijuana users in 2012, in 2020 that number grew to 47 million. While 2022 statistics are still being compiled, it is expected that 52 million Americans will have consumed cannabis. One study reported that 2.5 million teens between 12 and 17 years old consume marijuana regularly with 30.5 percent of 12th graders reporting cannabis use within the past year.

The consumption increase is tied to both ready access to the product and omnipresent marketing. Cannabis businesses use social media and digital advertising to promote their products and normalize cannabis use, targeting the youth demographic while circumventing advertising restrictions on cannabis products. But it is not just on the internet. On a recent trip through Western Massachusetts, cannabis dispensaries seemingly had a monopoly on the billboard market, with signs competitively flaunting their “Voted Best in the Berkshires” status, and medical dispensaries asking: “Why Wait for Better Health?” The ubiquitous presence of these advertisements perpetuates a rising sense that this product is safe for all—which is far from the case.

Ever More Potent Marijuana

Legalization has heralded the introduction of high-potency marijuana with significantly higher THC concentrations, the primary psychoactive compound in cannabis. Compared to the marijuana of the 1990s which had about 4 percent THC concentration, today's strains commonly boast THC levels of 15 to 30 percent, although some are as high as 95 percent. Additionally, the variety of products and formulations—including candy-like edibles, lollipops, THC-infused sodas and seltzers, waxes, dabs, and glass-like products called shatter—seem designed to attract young people. 

The Teenage Brain Has Not Fully Developed

Despite the changes in legalization, accessibility, acceptance, and perception, there is no new news in the neural development department. The teenage brain remains particularly vulnerable to the impact of marijuana. The prefrontal cortex—the region of the brain associated with judgment, decision-making, impulse control, and “executive functioning”—is the last to develop, generally not fully developed until the age of 25. Drugs such as marijuana interfere with the brain’s development at this important stage, and legalization or increased accessibility and acceptability will not change that. 

Cannabis use in teen years is also associated with depression, anxiety, and other mental health disorders. A recent study from Columbia University found that teens who use cannabis recreationally are two to four times more likely to develop psychiatric disorders such as depression and suicidality than those who don’t use cannabis at all. Conversely, many may use cannabis to mask or numb their feelings of depression, anxiety, or suicide—leading to delays in seeking and receiving help for their underlying mental health issues. 

Additionally, especially with the higher-potency products, we are seeing an increased incidence of cannabis-induced psychosis, with users experiencing frightening degrees of paranoia and confusion. Although there is unclear data linking cannabis use to schizophrenia, the data is clear that the adolescent brain is highly vulnerable in the late teens and early 20s.

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What We Need to Do 

Young people are going to encounter cannabis and people who use cannabis. The proliferation of cannabis dispensaries in our neighborhoods makes it impossible not to. While the change in perception of this drug as safe makes it easier to look the other way and dismiss casual marijuana use as a rite of passage or commonplace, teens and their families need to be aware of the effects of marijuana on their health and well-being.

It is often said that the first thing to do when you come to a medical emergency is to take your own pulse. When it comes to teenage cannabis use and attitudes about use, that means for adults to honestly examine their own use. A 2019 study from the University of Washington found that children of chronic users of marijuana were 4.5 times as likely to use marijuana and 2.75 times as likely to use alcohol versus children of nonusers. The adage “practice what you preach” will have a powerful influence on your teen’s behavior. 

But it is also important to preach. It is important to tell our teens that we care about their brain development and their mental health and that we don’t want them to use cannabis. Frank, open, and honest conversations are needed between teens and parents, teachers, coaches, and health care professionals. These conversations should be an opportunity to talk to and listen to our teens about their expectations, values, and attitudes about marijuana use and the use of other substances. If we don’t, we run the risk of more teens falling victim to our country’s bigger drug crises, as marijuana is frequently implicated as a “gateway drug”—a first venture into the use of more dangerous substances, including cocaine, amphetamines, benzodiazepines, and opioids. Lastly, if you or someone you know is struggling with cannabis use disorder, it is crucial to seek professional support sooner rather than later.