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Does Public Underestimate Risks of Marijuana Use In Young People?

Yes, Says Director of Addiction Psychology at Beth Israel Medical Center

by Matthew Flokos, reprinted by permission from the Harvard Press with contextual edits by Groton Herald editors.  


    Kevin Hill, M.D., gave a talk about the risks of marijuana use and vaping to an audience of several dozen concerned parents, teachers, and community members on Nov. 14 in the school Auditorium at the Public School Auditorium in Harvard Massachusetts.  Dr. Hill is director of addiction psychology at Beth Israel Deaconess Medical Center and the author of “Marijuana: The unbiased truth about the world’s most popular weed.”

    Hill’s presentation focused primarily on marijuana use. He stated his goal was to present the facts and science, rather than rhetoric. While he said he aims to reduce marijuana usage, he also criticized well-meaning people who exaggerate the risks of marijuana, stating that such tales, once disproven, weaken people’s trust in the scientific facts about marijuana, causing them to underestimate its danger. According to Hill, “The main difference between cannabis and alcohol is that people usually know the risks of alcohol, but are misinformed about cannabis.”

   Hill presented findings from several studies about marijuana usage. He stated that 22 million Americans used cannabis last year—a figure that has doubled in the past decade. Among adolescents, usage has remained fairly constant during this time, but perceptions of marijuana’s danger have steadily decreased. According to Hill, the commonly held belief that marijuana is not addictive is a myth. 

   Hill presented data showing that 9 percent of marijuana users become physically dependent (as opposed to 32 percent for tobacco and 15 percent for alcohol). 

  Alarmingly, this figure jumps to 17 percent among adolescent users, whose brains are still developing (and continue to do so until they are around 25 years old). According to another study, dependent users attempting to quit cold-turkey experienced symptoms similar to those trying to quit smoking cigarettes.

   Principal Dangers of Cannabis

   The main dangers of marijuana are that it can cause anxiety, depression, and reduced cognitive ability, Hill said, as well as exacerbate the risk of psychosis (such as schizophrenia) among those predisposed to it. He stated that dosage matters for all these effects, with the heaviest users losing as much as eight IQ points worth of cognitive ability and attention span. 

    More positively, he also presented a study showing that quitting marijuana reduced these effects, with users who quit cold-turkey showing significant cognitive improvement after just one week. He noted that the idea that marijuana helps people relax and avoid anxiety is a myth; a short-term calming effect hides a long-term increase in average anxiety levels.

   He cautioned parents who may have smoked in the past against basing their assumptions about marijuana on their own experiences. Hill stated that average THC content in marijuana in the ’60s to ’80s was 3 to 4 percent, but in modern marijuana, it averages 12 percent. Much higher concentrations can be achieved with specialized techniques, such as dabbing or the use of e-cigarette cartridges. THC is one of the two active ingredients in marijuana and is the one that provides the psychoactive experience that allows users to get high. The other, CBD, has some medical uses and also reduces the effectiveness of the THC when paired with it. According to Hill, synthetic marijuana is more dangerous than natural marijuana because it contains similar amounts of artificial THC but without CBD, leading to an unexpectedly stronger effect and risk of overdose.

New Threat of Vaping

   Hill also spoke about the use of e-cigarettes, which he claims has increased by 90 percent since 2015. According to a study, 40 percent of adolescent cigarette users have never used a traditional cigarette, receiving their nicotine exclusively through vaping. He stated that vaping products include far higher concentrations of nicotine than traditional cigarettes, with one vape pod containing as much nicotine as 20 cigarettes. While some of the health risks associated with smoking cigarettes are absent from vaping, others are worsened by the higher concentration of nicotine. Nicotine’s primary long-term effects include increased adrenaline and blood pressure, both of which lead to higher rates of heart failure. According to Hill, the vast majority of vaping is currently nicotine based, with cannabis or other products being in the extreme minority.

   In response to a question from the audience, Hill stated that THC stays in a person’s system long enough to impair driving for approximately 16 hours but is detectable by drug tests for long after that. When asked whether marijuana is a gateway drug, Hill gave a lengthy explanation. He said that marijuana use is definitely a “risk factor” and is correlated with the use of other drugs, but he dislikes the term “gateway drug” because, in his experience, he finds that it is counterproductive to think about drug use as a railroad leading to any specific outcome.

   Hill’s main advice to parents and other adults was twofold. He emphasized that maintaining open communication with kids is important, as they need to be able to trust adults in order to work out plans to either avoid or stop using drugs. He also recommended regularly communicating messages, both verbal and by example, of drug avoidance and safety. According to Hill, even kids who appear not to be listening will often take repeated warnings to heart.

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