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Marijuana Use and the Developing Teen Brain

Tips and talking points for parents

Published on: June 01, 2020

hands with red painted fingernails holding a joint

“But it’s legal, so it’s safe.”

“It’s just weed. It’s a natural drug.”

“My parents smoked marijuana in high school.  I don’t know what the big deal is.”

“It’s the same as buying a beer — they’re both legal at age 21”.

As a pediatric psychologist with a specialty in working with adolescents, these are just some of the comments I hear from my teen clients when talking with them about their marijuana use. Parents of teenagers in Washington state have an especially unique challenge in how they talk with their kids about marijuana. Since marijuana is legalized for adults over the age of 21 in our state, it’s understandable that many teens assume it’s “safe.” In reality, however, we know the opposite to be true given all we have learned about the impact of marijuana on the developing brain. 

Thanks to the many advances in research on the developing brain, we now know that the prefrontal cortex — the part of the brain responsible for impulse control, judgment and higher-level decision-making — is still developing until age 25. Given this, the developing brain is especially susceptible to the negative effects of marijuana. In the past several years, there have been a number of studies showing that marijuana can have a substantial impact on the adolescent brain.

A 2014 literature review of neuroimaging and neurocognitive findings of the effects of cannabis on the adolescent brain conducted by Joanna Jacobus and Susan F. Tapert revealed that teens who engage in heavy marijuana use often show disadvantages in brain development and alterations in brain functioning. Furthermore, findings from this important literature review suggested regular marijuana use negatively impacts neurocognitive functioning in the areas of attention, memory and concentration. THC, the main psychoactive compound in marijuana that gives the “high” sensation, interferes with how information is processed in the hippocampus, which is the part of the brain responsible for forming new memories. 

We now also have reason to be concerned about the long-term impact of adolescent marijuana use as well as the risks of early-onset marijuana use. A study published in 2014 by Justine Renard and colleagues showed that chronic exposure in the brain to THC during adolescence can dramatically alter brain maturation and cause long-lasting neurobiological changes that ultimately affect the function and behavior of the adult brain. This study also found early marijuana use to be associated with a two-fold increase in the risk of developing a psychotic disorder. Additionally, a 2003 study by Harrison G. Pope and colleagues out of Harvard Medical School revealed poorer cognitive performance on verbal reasoning tasks associated with early (before age 17) marijuana use.

In connection with the cognitive impacts, regular marijuana use is linked to a reduced likelihood of completing high school or obtaining a college degree. Research conducted by Jason Kilmer, Ph.D., at the University of Washington Department of Psychiatry and Behavioral Sciences has demonstrated that the more a student uses marijuana, the more they are likely to experience specific academic struggles. This includes being more likely to skip classes, lose credits, have a lower GPA and take longer to graduate from college. 

To further complicate matters, the marijuana available nowadays has a much higher THC potency than the marijuana from years ago.  A report published in Biological Psychiatry in 2016 that examined the changes in cannabis potency over the last two decades in the United States revealed that potency has increased steadily over time. Higher THC in the receptors in the adolescent brain means a greater impact — not only a “higher high,” but more risk for paranoia, panic and even hallucinations. 

As if all of this was not compelling enough reason to help our teens better navigate the real risks of marijuana use, we now have the complications of the COVID-19 pandemic. An article by Jan Hoffman published in the New York Times in April of this year discusses how smoking marijuana products damages lung cells, causes lung inflammation and can even affect the ability to fight off infection. According to Jonathan Winickoff, M.D., a professor at Harvard Medical School, “Clean air is what the lungs should be inhaling, especially during a global pandemic.”

We now know that the course of brain development in teens is much more fragile and longer than what was once understood. We also now know that marijuana is more potent and harmful to the developing brain than we initially realized. Of course, the challenge is how to reach teens with this information. As any parent of a teen knows, our best efforts to teach and educate are not always openly received. Below are some strategies for talking with your teen about this important topic.

Open a dialogue. Ask your teen open-ended questions to get the conversation going. Allow your teen to be the expert on what they know about teen marijuana use. Show curiosity and interest in their responses. Refrain from jumping in with information until they show openness to hearing it.  

Avoid lecturing or overtalking. Once your teen shows a willingness to engage, think “sound bites” rather than soapbox. Simple attention-catching phrases like “I want you to do all you can to stay healthy and well during this pandemic” and “I hope you can delay this decision until age 25 when your brain is fully developed” are some examples.

Keep an open mind. Try to hear your teen’s perspective, even if they think you are overreacting about “just weed.”  Say, “I can see you think I’m making a big deal out of this. What would make it feel like a ‘big deal’ to you?” This can help your teen think about their boundaries with marijuana use, something that is not often discussed with their peers.  

Externalize it. Sometimes teens are more likely to discuss their observations of another teen’s marijuana use, whether it be that of a peer or someone on TV. Allow another’s experience to provide a foray into the discussion if it works for your teen.

Keep it casual. Stay calm and don’t act overly eager! Use a bit of humor when you can and try to keep it light. Sometimes being engaged in other tasks while approaching sensitive topics — emptying the dishwasher, walking the dog, folding laundry — takes the pressure off your teen and helps the conversation feel lower-stakes, which in turn might get them talking. Avoid asking for a “sit-down” or “family meeting,” as that is only likely to raise your teen’s anxiety and, in turn, their resistance.  

If they shut you down, try again later. Sometimes it takes many, many attempts at opening conversations with teens before they bite. Don’t show frustration or lock horns. Shake it off and try again another time.  

Above all, it’s important to not give up on talking about this topic with your teen.  Their precious developing brain deserves your persistence!

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