Marijuana 101: Does Substance Abuse Stunt Teenage Brain Development?

With the legalization of recreational marijuana use in Colorado, Washington and Oregon, a growing number of teens believe marijuana use is harmless. Widespread news coverage focused on medical marijuana and the substance’s potential therapeutic effects also could add to this sentiment. But what solid research has been conducted to really look at the effects of marijuana use on the teen brain? Read on to learn the facts about teen marijuana use.

Marijuana Use and the Teenage Brain

Handfuls of studies have attempted to analyze the effects marijuana use has on the brain. The majority of research, including this specific study published in the journal Proceedings of the National Academy of Sciences, finds that heavy use of the substance (more than three times per day for at least four years) is linked to adults who tend to have smaller gray-matter volumes in the orbitofrontal cortex. “We also saw that the younger you are when you start using marijuana regularly, the greater the changes in the brain,” Francesca Filbey, study author, told

Why is Marijuana More Harmful for Teens?

In fact, other studies have proven this same observation noted by Filbey. According to a study titled “Persistent cannabis users show neuropsychological decline from childhood to midlife” published in the journal Proceedings of the National Academy of Sciences of the United States, teen marijuana use led to an eventual eight-point drop in participant IQ. “Interestingly, people who picked up the habit as adults had no IQ drop, suggesting that marijuana may not be as harmful to the mature brain.”

Dr. Susan Tapert, who was not involved in conducting the study, notes that one possibility for these results may be that teen brains are more susceptible to marijuana’s effects, as many of the areas that are still developing in the teenage brain contain high cannabis receptor density. Another possibility could be that teens who use marijuana could be less motivated to participate in activities that exercise intelligent thinking, such as attending class or reading a book. Still, creating a solid connection between cause and effect proves tricky, and other factors—environmental, genetic—may also play roles.

Actionable Advice for Parents

Confusing and contradictory information on teen marijuana use can easily become too overwhelming to navigate. As a parent, you may be the strongest influence in preventing your teen from abusing marijuana and other drugs. Many adolescents polled in a Partnership for a Drug-Free America Attitude Tracking Study cited losing their parent’s respect as a main reason they do not smoke marijuana. Marijuana may be the most widely used illicit drug in the country, but that doesn’t mean it’s welcome in your family. If you suspect your teen is abusing marijuana and are looking for more information, Pacific Quest can answer any questions you may have. Please feel free to reach out to our admissions team at any time by contacting us here.

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