Dr. Pat Consults: Pot Use in Adolescents — Is It Safe?

Dr. Riddle Responds:

Dear Marci,

Now that marijuana is becoming legalized for both medicinal and recreational uses, your question is increasingly important.

First, despite what your may have heard in social conversations, marijuana is actually addictive. About 9 percent of those who try it become addicted, and the risk increases considerably for those who start experimenting during adolescence and those who smoke regularly. Indeed, 25 percent to 50 percent of daily smokers develop addiction with withdrawal symptoms that make it harder to quit.

Smoking during adolescence and early adulthood can have a significant impact on brain development. Neuroimaging studies that look at connections in the brain show that smoking marijuana affects regions that are critical for alertness, learning and memory. Since the brain continues to develop until at least 21 years of age, your son is still actively laying down connections that can be affected by his marijuana use. This may be part of the reason why frequent marijuana use in adolescence is linked to lower IQs in adulthood. Also, although many recognize that they are mentally slower while acutely intoxicated, they may not realize that studies have shown that a certain degree of slowing continues for days after use, which can have a significant effect on performance.

Your friends claim that marijuana is “safer than alcohol.” Note that while we’ve all been taught not to drink and drive, many don’t realize the dangers of smoking marijuana and driving. Smoking even a fairly small amount doubles one’s risk for a traffic accident; at higher levels of use, the rate increased to 3 to 7 times, similar to the effects of alcohol.

Marijuana use is associated with a number of mental health issues. For those already at risk of developing a psychotic disorder like schizophrenia – such as having a close relative with the disorder – marijuana use is associated with increased likelihood of developing a psychotic disorder and an earlier onset of symptoms. Some studies have suggested that there is an increased rate of anxiety and depression among users. It is unclear, however, whether the drug use leads to the mental illness or is a result of the “self-treating” for the illness — or neither.

Your friends are  right in some ways – evidence suggests that marijuana is safer than cigarettes with regard to lung cancer, although studies have been somewhat mixed. Interestingly, marijuana actually contains about three times the tar found in cigarettes and 50 percent more carcinogens (cancer-causing agents). However, people tend to smoke far fewer joints than cigarettes, which may be why we don’t see increased rates of lung cancer. Still, frequent marijuana smokers do appear to have more respiratory infections than non-smokers, as well as worsening of underlying lung problems, like asthma or cystic fibrosis.

I applaud your willingness to have these difficult conversations with your son who is on the cusp of adulthood. You won’t be able to control his choices for much longer so it is even more important that you  make efforts to discuss the issue of marijuana use in a calm, nonjudgmental way, which will keep the channels of communication open on this important topic. You may want to discuss the family history of addiction and emotional illness as an important reason for your concern about pot, alcohol and all illicit drug use.

Dr. Megan Riddle



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Marijuana Anonymous.  (2014). The Twelve Questions of Marijuana Anonymous

Saad, L. (2013). In U.S., 38% Have Tried Marijuana, Little Changed Since ’80s. Gallup.

Teitelbaum, S. A., DuPont, R. L., & Baily, J. A. (2014). Cannabis use disorder: Treatment, prognosis, and long-term medical effects. In A. J. Saxon (Ed.), on the site UpToDate.

Volkow, N. D., Compton, W. M., & Weiss, S. R. (2014). Adverse health effects of marijuana use. N Engl J Med, 371(9), 879.

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