Massachusetts Medical Society's Physician Focus

July 2012

Youth Substance Abuse


  • The leading causes of death among adolescents are motor vehicle crashes, unintentional injuries, homicides, and suicides - all are linked to teen drinking and drug use.

  • Alcohol is responsible for more deaths than all other drugs combined, yet more than 30 percent of parents provide alcohol to their teenage children.

  • Marijuana is the most commonly used illicit drug among teens. It is highly addictive and affects vision, sensation, coordination, and movement.

  • Abuse of prescription drugs – stimulants, depressants, and pain relievers – is also high and growing.

Get the Flash Player to see this player.

Substance abuse by adolescents accounts for almost 60 percent of accidental deaths among teens and poses significant risks to physical and mental health. Alcohol and marijuana are the two most abused substances, with prescription drugs growing in popularity.

While addiction to alcohol or drugs is rare among young people (only 3 percent of 12-18-year olds meeting the criteria for addiction), the dangers of abuse are real and many and too often result in tragedy, says John R. Knight, M.D., Director of the Center for Adolescent Substance Abuse Research at Boston Children’s Hospital: “You don’t have to be addicted in order to die or have something terrible happen as a result of substance abuse.”

Dr. Knight, who is also an Associate Professor of Pediatrics at Harvard Medical School, discusses the varied aspects of youth substance abuse on the July edition of Physician Focus with the Massachusetts Medical Society with program host and primary care physician Mavis Jaworski, M.D.

Among the topics of conversation are the factors that cause young people to abuse these substances, the consequences of this behavior, and the steps parents and others can take to address the problem.

Dr. Knight says teenagers are at high risk from substance abuse because of the way their brains respond to those substances.

“The brain undergoes major development all through adolescence,” he says, “and continues into the mid to late 20s. A person develops the capacity for vision, movement, and coordination well before judgment or impulse control. And that’s why it’s so dangerous for adolescents to be putting psychoactive substance into their brains. They respond differently than adults and are at much greater risk.”

“Alcohol is the greatest threat to your teen’s life, health, and future,” he tells parents. “It accounts for more deaths than all other drugs combined and is the most dangerous of all the drugs.” The statistics bear that out: more than 35 percent of teen deaths from motor vehicle crashes are directly linked to alcohol, when the driver was intoxicated. Yet, amazingly, says Dr. Knight, “More than 30 percent of parents provide alcohol to their teenage children.”

Marijuana, the most commonly used illicit drug among teens, is more dangerous than people think, he says. “Long-term changes in both the structure and function of the brain are caused by cannabis,” he notes. “The leading active ingredient in marijuana - THC or tetrahydrocannabinol, – affects judgment, memory, coordination, vision, sensation, and movement.”

The movement to accept ‘medical marijuana’ has led many teens to assume that it’s safe, and it’s one of the top two questions Dr. Knight gets when talking to teens. “The very term medical marijuana is a political statement,” he says. “It is not a medical fact, and there is no safe dose. And even though marijuana does not cause physical symptoms of withdrawal, it is highly addictive psychologically.”

The abuse of prescription drugs, such as painkillers and stimulants – is growing part of the problem of youth substance abuse. “Youth look at these substances as medicines, as being safe and effective,” he says, “but they lose sight of one critical phrase – ‘when used as directed’. Many teens, he says, find these pills right in their own home medicine cabinets.

Dr. Knight offers clear advice to parents: “Tell your teenagers you expect them not to drink until they’re 21 and you expect them not to use drugs and tell them frequently. If you give them the message frequently – once a month – then you’re immunizing your children from getting involved with substance abuse.”

Watch the accompanying video for additional information and conversation about the distinctions among use, abuse, dependence and addiction; the common ways teenagers die from substance abuse; the signs and symptoms of substance abuse and what specifically parents should look for; how such abuse impacts health; and the phenomenon of “pharming parties” held by teens.

Editor’s Note: Dr. Knight, who has devoted his career to reducing and eliminating substance abuse by young people, has produced a website, Teen Safe, offering parents the chance to “learn how to keep your teen safe in just 15 minutes.” Click on the link below to access the site.

MMS/Richard Gulla


Center for Adolescent Substance Abuse Research

Students Against Destructive Decisions

NIDA For Teens

Get the Flash Player to see this player.

Youth Substance Abuse PSA

From left: Mavis Jaworski, M.D.; John Knight, M.D.
hi-res photo
promo slide