Teen Marijuana Use

How to tell whether your teen is using—and what to do about it

While recent debate over legalization of marijuana may be downshifting public attitudes about its use, experts remind parents that adolescents and young adults face an accelerated risk of harm. Marijuana use affects adolescent brain development, and early use of marijuana, alcohol, or any other mood-altering drug puts a young person at significantly increased risk of full-blown addiction later in life.

Experts at the Hazelden Betty Ford Foundation specialize in the prevention, assessment, and treatment of addiction and co-occurring disorders among adolescents and young adults ages 12–25. Jim Wynne, LADC, a program supervisor at Hazelden in Plymouth, Minnesota, works with young people in addiction treatment and their families. He looks at the resurgent national dialogue about marijuana as a timely opportunity for parents to get up to speed on the facts and trends, talk with their teens and young adults about expectations and consequences, and take action if they suspect use.

Stick with the facts.

Wynne cautions parents against exaggerating the dangers of marijuana use, a tactic that could cause parents to lose credibility. The basic facts are persuasive enough.

  • Changes brain structure. Brain imaging studies of marijuana users have shown changes in actual brain structure, particularly among adolescents. A 2014 Harvard-Northwestern study of young adult marijuana users found abnormalities in the shape, density, and volume of the part of the brain associated with motivation, pleasure and pain, and decision making.*
  • Impairs learning and thinking. Brain function related to problem solving and memory can be negatively impacted by early teen marijuana use. A 2012 study showed that teens who were dependent on marijuana before age 18—and who continued using it into adulthood—lost an average of eight IQ points by age 38.**
  • Ups the risk of addiction. The younger a person is when he or she starts using a mood-altering substance, the greater the possibility of developing addiction. According to the National Center on Addiction and Substance Abuse at Columbia University, nine out of ten Americans who meet the medical criteria for addiction started using drugs before the age of 18.

Trust your instincts.

There's plenty of information about the various telltale physical and behavioral signs of marijuana use in teens—bloodshot eyes, paraphernalia (rolling papers, pipes), difficulty focusing, and lethargy. But Wynne says the most common warning sign is dishonesty. "Teens who use marijuana need to be dishonest—they need to sneak around and lie about where they’ve been, who they've been with, and what they've been doing." He tells parents to open their eyes and trust their gut if they sense something's not right—and to keep the lines of communication open with their child. "Revisit your family's rules and consequences around drug and alcohol use and reinforce your expectations around academic achievement and household responsibilities."

Check your attitude.

According to a federally funded study tracking student attitudes since 1975, the perceived risk of harm associated with teen marijuana use is reaching a new low. Two-thirds of high school seniors today don't think regular marijuana smoking is harmful.*** And many parents may have a similar outlook, says Wynne—which could delay or deter getting help for a young person when needed. "The mind-set that marijuana isn't addictive or that smoking pot is a teenage rite of passage can be dangerous if it prevents parents from stepping in when there are signs of trouble," says Wynne.

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