Cannabis and the Teenage Brain

This exercise is a part of Educator Guide: Water Burbling Physics and THC and the Teenage Brain / View Guide

Directions for teachers:

To engage students before reading the article, have them answer the “Before Reading” questions as a warmup in class. Then, break students into small groups. Instruct them to read the introduction of the online Science News article “The teen brain is especially susceptible to the harms of THC.” Afterward, have them answer the “Introduction” questions.

Assign each group a different section of the article to read. Then ask them to answer the relevant “During Reading” questions. Once students are finished with their section’s questions, have each group summarize their section for the rest of the class in 2-3 sentences. This should describe the main scientific claims in the section and supporting claims with data from the article.

After having student groups share their summaries, use the “After Reading” questions as a class discussion or as homework.

This article also appears in the February 10 issue of Science News. Science News Explores offers another version of the same article written at a middle-school reading level. Post this set of questions without answers for your students using this link.

Directions for students:

Read the online Science News article “The teen brain is especially susceptible to the harms of THC.” Then answer the following questions as directed by your teacher. Because the article is long, the questions are broken up by the article’s subheadings.

Before Reading

1. Discuss the following question as a class. Frequent use of which of the following could pose a high risk of harm to you? Ask students to rank the following substances from most harmful to least: cigarettes, alcohol, cocaine, heroin and cannabis.

Answers will vary.

2. Human brains carry out a lot of growth and development during adolescence. With this in mind, how important is it to make healthy brain decisions during our teen years versus when we are adults? In other words, is it more, less, or equally important for us to make healthy decisions as teens and adults, based on what we know about brain development? Explain your answer.

Answers will vary.

During Reading


1. What percent of 12- to 17-year-olds perceive “great risk of harm” from smoking marijuana once or twice a week?

Only 35 percent of this age group perceive a “great risk of harm” from this habit.

2. What idea does the widespread availability of cannabis for adults promote in young people, according to Beth Ebel?

Ebel says that the widespread availability of cannabis to adults promotes the idea that cannabis is safe.

3. What is the full name and abbreviation of the main psychoactive chemical in marijuana plants? How has the percentage by weight of this chemical in the marijuana plant changed in the past few decades?

Delta-9-tetrahydrocannabinol, or THC, is the psychoactive chemical in marijuana. The total share of THC by weight of the plant has increased from around 4 percent in 1995 to about 20 percent today. Plants are bred to contain more THC today.

“How does THC affect the teen brain?”

1. Why is adolescence a risky time to be using cannabis, according to Yasmin Hurd?

Adolescence is a risky time to use cannabis because the brain is still developing.

2. Describe three aspects of human function that are influenced by the endocannabinoid system.

Answers may include any of the following. This system plays a role in brain development. This system helps control anxiety, pain, memory and motivation. This system also affects how the brain’s structure changes as an adolescent develops into adulthood.

3. Describe how THC can interfere with the body’s endocannabinoid system. What are some impacts of this?

THC can reduce receptors in the brain not only tied to memory but also that lead to long-lasting problems with memory and learning. THC also can thin the prefrontal cortex, a region which helps with problem-solving and emotional regulation.

“Marijuana use is linked to mental health harms”

1. What is cannabis-use disorder? 

This is a disorder in which people struggle to stop using cannabis despite it causing health problems or otherwise adversely affecting their daily lives.

2. Researchers studied rates of depression and suicidal thoughts among adolescents who consumed cannabis. Those who used the drug had a higher prevalence of depression and suicidal thought then did those who didn’t. Now refer to the graph, “Cannabis and mental health.” Provide data from it that supports the researcher’s claim.

The study showed that people who used cannabis in the past year were more than twice as likely to develop these problems. Those with cannabis-use disorder were more than over three times as likely to develop the problems.

3. What does the article highlight as possible future consequences for teens who become dependent on marijuana at a young age?

Daily use of cannabis as a teen could lead to becoming dependent on cannabis as an adult, to using other drugs, to attempt suicide, and to lower the likelihood of finishing high school.

“The risks of using concentrated cannabis products”

1. According to a 2020 study, how did preferred methods of cannabis consumption by teens change from 2015 to 2018?

Compared to 2018, teen cannabis users who smoked cannabis dropped by 90 percent, while the share of teen users who vaped cannabis increased by 35 percent.

2. What is “high-potency cannabis?”

High-potency cannabis refers to products that contain a THC content of 10 percent or more.

3. What are some risks of using high-potency cannabis? Why do Ebel and Hurd argue that high-potency products are alarming?

Higher potency could lead to a higher risk of psychosis and cannabis hyperemesis syndrome. High-potency products are alarming because the effects haven’t been studied, so there remain many potential unknown risks.

After Reading

1. Why might today’s teens be at even greater risk from cannabis use compared to teens in the past? Refer to information from this article to support your answer. To what extent might this greater risk lead some adults to misunderstand risks of cannabis use by kids?

Answers will vary. Students point out that modern cannabis is bred to contain higher levels of THC than in the past. This could lead some adults to believe that cannabis might be no more harmful than when they were kids.

2. This article describes various studies supporting the conclusion that THC causes harm to developing brains. Pick one of these studies and explain how the evidence from this study supports the conclusion that THC can harm the teenage brain.

Answers will vary regarding the chosen study. But one option is the 2019 study by Hurd’s team. It found that injections of THC into the brains of adolescent rats resulted in changes to the prefrontal cortex and that connections between the nerve cells were disrupted when compared to nerve connections in rats that had not been injected with THC.