When queried about harm from frequent substance use, teens often recognize risks. They associate cigarettes, alcohol, cocaine, and heroin with high danger. However, a notable number tend to overlook cannabis.
Merely 35% of adolescents aged 12 to 17 recognize a “significant risk of harm” from smoking marijuana once or twice weekly, as per the National Survey on Drug Use and Health.
This viewpoint is shared by some parents. They often fail to grasp that the substances utilized today “differ significantly from their high school days,” notes Kelly Young-Wolff, a licensed clinical psychologist and research scientist at Kaiser Permanente Northern California Division of Research in Oakland. If their offspring are using cannabis, parents might believe, “‘it’s not that harmful, at least they’re avoiding more harmful drugs.’”
However, contemporary cannabis products are substantially more potent, potentially elevating the dangers of addiction and psychosis, compared to the past. Marijuana plants have been genetically modified to contain higher levels of delta-9-tetrahydrocannabinol (THC), the primary psychoactive compound. In 1995, THC constituted about 4 percent of the weight of marijuana plant material; now, marijuana with a THC potency of 20 percent or more is prevalent.
Surpassing this are concentrated cannabis derivatives, such as wax, budder, and shatter, which can boast a THC potency as elevated as 95 percent.
Cannabis is legally accessible for recreational use in 24 states and Washington, D.C., and permitted for medical use in 38 states and D.C. The widespread availability of cannabis “conveys the notion that it’s harmless,” asserts pediatrician Beth Ebel of the University of Washington School of Medicine and Seattle Children’s Hospital. However, this “is an inaccurate assumption.” THC can impact brain chemistry “in unintended ways,” Ebel warns. “Some of the most severe consequences can result in lifelong health implications, particularly for a young individual.”
Concentrated cannabis products are so extraordinarily potent and divergent from traditional cannabis that “we need to start labeling them differently,” insists neuroscientist Yasmin Hurd of the Icahn School of Medicine at Mount Sinai in New York City. “These are essentially new drugs.”
How does THC affect the adolescent brain?
Similar to other substances, using cannabis during adolescence poses significant risks. “The adolescent brain is still in the process of developing into early adulthood,” notes Hurd. During this phase, connections within the brains of adolescents are being established, strengthened, or pruned. “Your brain is trying to determine, ‘what is important that I need to learn, and what is important that I need to retain,’” explains Ebel, and THC negatively impacts this process.
THC binds to the CB1 receptor, a primary component of the endocannabinoid system. This intricate system influences various bodily functions. In the brain, the endocannabinoid system plays a pivotal role in development and regulates anxiety, pain, memory, behavioral motivation, and more.
The endocannabinoid system also contributes to the structural changes occurring as developing teen brains mature. However, THC can disrupt the system's signaling during this critical period, leaving a lasting impact on the brain's structure.
Animal studies have revealed that exposure to THC during adolescence can diminish CB1 receptors in the brain, leading to persistent issues with memory and learning. The prefrontal cortex, essential for problem-solving and emotional regulation, is one of the areas affected by the psychoactive compound. In adolescent rats administered THC, nerve cell protrusions connecting with others were prematurely trimmed, disrupting the circuitry of the prefrontal cortex, as reported by Hurd and colleagues in Molecular Psychiatry in 2019.
There is also human evidence indicating that THC alters the brains of teenagers. A study analyzing nearly 1,600 magnetic resonance images of the brains of around 800 adolescents, taken at an average age of 14 and 19, found a correlation between cannabis use over five years and an accelerated thinning of the prefrontal cortex, as reported in JAMA Psychiatry in 2021. While cortical thinning is normal in adolescence, it is likely associated with the pruning of underused connections. However, accelerated thinning suggests that the process deviates from the typical developmental plan. The researchers hypothesize that this accelerated thinning might be linked to the premature loss of nerve cell protrusions observed in the rat study.
Marijuana use is linked to mental health harms
Engaging in cannabis jeopardizes the mental well-being of teenagers, even for those using it recreationally. This holds true for adolescents aged 12 to 17 whose cannabis usage doesn't meet the criteria for a substance use disorder. According to a study involving over 68,000 adolescents, published in May in JAMA Network Open, those in this age group using cannabis without reaching the threshold for a substance use disorder were approximately twice as likely to develop depression or experience suicidal thoughts compared to non-users.
The risks escalate for individuals grappling with cannabis use disorder, diagnosed when usage disrupts daily life and proves challenging to quit, among other symptoms. The JAMA Network Open study revealed that adolescents with cannabis use disorder were 2.5 and 3 times more likely to suffer from depression or entertain suicidal thoughts, respectively, in contrast to those who refrained from cannabis use.
Initiating cannabis use during adolescence is more likely to result in dependence compared to starting as an adult, akin to alcohol, cocaine, and nicotine. Adolescents, in contrast to young adults, exhibit a higher susceptibility to developing dependence within a year of commencing marijuana use. A 2021 study in JAMA Pediatrics revealed that 11 percent of those aged 12 to 17 progressed to cannabis use disorder within 12 months, while only 6 percent of those aged 18 to 25 did. Over three years, the prevalence increased to 20 percent for adolescents compared to 11 percent for young adults.
Despite the risks, many teens turn to marijuana as a coping mechanism. A study examining motivations of high school seniors for cannabis use found that reasons related to coping, such as escaping problems, relieving tension, or managing anger, doubled in prevalence over the last four decades, as reported in the Journal of Studies on Alcohol and Drugs in 2019. In the context of California's cannabis legalization for adults, clinicians have observed that adolescents often use cannabis as a form of self-medication to alleviate symptoms of depression or anxiety, according to Young-Wolff's research.
Ebel has also observed this phenomenon, noting that as the drug's effects wear off, users become more anxious than before, perpetuating a cycle of increased use.
When marijuana becomes a routine part of a teen's life, it can alter their future trajectory. A study in Australia and New Zealand compared the frequency of cannabis use before the age of 17 with participants' outcomes by age 30. Those who used cannabis daily were more likely to develop cannabis dependence, use other drugs, attempt suicide, and less likely to complete high school, as reported in the Lancet Psychiatry in 2014.
Moreover, cannabis addiction is linked to the development of psychiatric disorders such as schizophrenia. A study of nearly 7 million Danish individuals aged 16 to 49 found an association between cannabis use disorder and schizophrenia, reported in May in Psychological Medicine. The association was more pronounced for males, particularly between the ages of 16 to 25. The researchers estimate that in 2021, without cannabis use disorder, approximately 15 percent of schizophrenia cases in males and 4 percent in females would not have occurred.
Cannabis and mental health
Adolescents who met the diagnosis for cannabis use disorder or who used the drug recreationally had a higher prevalence of depression and suicidal ideation than those who didn’t use cannabis.
The risks of using concentrated cannabis products
While smoking the marijuana plant remains the predominant method among teens, there is a burgeoning trend in vaping cannabis concentrates. According to a study of high school seniors, between 2015 and 2018, among past-year cannabis users, smoking decreased from 95 percent to 90 percent, while vaping increased from 26 percent to 34 percent. The prevalence of daily use was higher among those who vaped, reaching 29 percent, compared to those who smoked at 18 percent, as reported in JAMA Pediatrics in 2020.
Early evidence suggests that high-potency cannabis products are linked to an elevated risk of psychosis, a symptom of schizophrenia. In a study of adults, daily use of high-potency cannabis products resulted in nearly five times the risk of psychosis compared to non-users, reported in Lancet Psychiatry in 2019. High potency, for the study's purposes, was defined as having 10 percent THC or higher.
There are also reports of an increase in cannabis hyperemesis syndrome, a complication of high-potency cannabis use leading to abdominal pain, nausea, and recurrent vomiting. A Canadian study found that emergency department visits for the syndrome surged 13-fold from 2014 to 2021.
Concentrated cannabis products, as noted by Ebel, are largely unexplored and present "new and alarming health risks." Hurd emphasizes that due to the incomplete understanding of the health impact from high-potency products, users essentially serve as test subjects.
In line with other substances, public health officials recommend that parents engage in conversations with their children about the risks of cannabis use. Particularly with indications that teens resort to cannabis for self-medication, Young-Wolff advises parents to investigate changes in their child's behavior. It is also crucial for parents to reflect on the messages they convey about marijuana. Young-Wolff notes that clinicians have observed increased cannabis use among parents and a more permissive attitude toward teen cannabis use. This shift can make it challenging to dissuade kids from using, she remarks.
For adults participating in the newfound legality of marijuana, Young-Wolff emphasizes, "If you are going to use cannabis, don’t use it in front of your children."
