Teen Marijuana Use: How Concerned Should We Be?

by Vivian Diller, Ph.D.

Is there a familiar aroma emanating from your kid's room? Do you shake your head and ignore it thinking, "Hey, I got high when I was a teen and I turned out OK, right?" Well, think again.

While recent studies show some good news regarding the decline in teenage cigarette smoking and alcohol abuse, the bad news is that more are using marijuana and doing so more regularly than ever before. These studies also reveal a growing perception that marijuana use is harmless -- a confluence of trends that could lead to an entirely new health crisis among our teenage population. Take a look at some of the latest research about marijuana use and consider talking to your teen about it.

• Who is getting high and how often: Today, children are experimenting at increasingly younger ages. The Department of Health and Human Services reported that the average age of first-time users in 1999 was 16.4 years. More recently, studies are looking at the regularity of marijuana use by teens. A large group of 8th, 10th and 12th graders were surveyed in a study conducted under a grant from the National Institute on Drug Abuse (NIDA). Results showed that 6.5% of high school seniors smoke marijuana on a daily basis. Nearly 23 % of these seniors said they smoked in the month prior to the survey and just over 36 % said they smoked within the previous year. Among 10th graders, 3.5 % said they use marijuana daily, 17 % smoked in the previous month and 28 % in the past year. Close to half of all these students in the study viewed marijuana as having few, in any, adverse effects.

• Potential for physical addiction: The main psychoactive substance in today's marijuana (delta-9-tetrahydrocannabinol, or "THC") is the same as it was in the pot smoked years ago. But over the past 15 years, the concentration level of THC has more than doubled. Dr. Nora D. Volkow, director of the National Institute on Drug Abuse, recently talked to the New York Times about the pot that kids are getting high on today. "It's much more potent marijuana, which may explain why we've seen a pretty dramatic increase in admission to emergency rooms and treatment programs for marijuana," said Volkow. Those who try to quit on their own face withdrawal symptoms -- including mood swings, anxiety attacks and depression -- and are often surprised by the intensity and duration of their discomfort. According to the Caron's Adolescent Treatment Center, marijuana has overtaken alcohol as the primary drug of choice for teens entering their inpatient treatment programs.
• Psychological reliance: The increased potency in today's pot not only has physical consequences, but psychological ones as well, with teens being the most vulnerable victims. Experts find that when youngsters start smoking marijuana at an early age, it is often used with greater frequency and in larger quantities than if started later in life. While we tend to dismiss the potential of marijuana dependency -- especially when compared to tobacco, alcohol or illegal drugs like heroin -- about 1 in 6 teens will become addicted, says Dr. Volkow. If marijuana is regularly used to relieve the challenging emotions typical of adolescence, it easy to see how occasional smokers may become addicted. Teens who gain a sense of confidence by smoking weed in social situations or use it to help them relax or sleep will no doubt find it compelling to use again. Instead of developing internal skills to cope with life, marijuana can become their go-to source for comfort.
• Impact on the heart: The THC in pot passes into the bloodstream from the lungs (if smoked) or digestive tract (if eaten). It then flows to the brain and other organs throughout the body. When smoked, it is absorbed more rapidly than when ingested through food or drink, but either way it can increase the heart rate by 20-100 % and remain raised for up to three hours. According to one studyreported by The National Institute on Drug Abuse (NIDA), "it was estimated that marijuana users have a 4.8-fold increase in the risk of heart attack in the first hour after smoking the drug, " While this risk may increase with age and depend on cardiac vulnerability, marijuana has been shown to lead to heart irregularities, palpitations and arrhythmias.
• Impact on lungs: While marijuana contains some of the same carcinogens that tobacco does, most pot smokers assume they don't inhale as often and therefore the smoke has less impact on their lungs. But studies show regular marijuana use can lead to many of the same respiratory problems experienced by tobacco smokers, including increase in phlegm production, chronic cough and the risk of lung infections. In a recent study by the NIDA found that people who don't smoke cigarettes but who use marijuana regularly tend to have more health problems that keep them out of work (primarily due to respiratory illnesses) than do non-smokers.
• Influence on cognitive development: Whether marijuana is ingested or smoked, THC reaches receptors in the brain that influence pleasure, memory, thinking and concentration. By over-activating these receptors, marijuana creates the enjoyable high that users experience. But with long-term use, over-activation appears to interfere with memory, problem solving and learning. The New York Times reports, "The most disturbing new studies about early teenage use of marijuana showed that young adults who started smoking pot regularly before they were 16 performed significantly worse on cognitive tests of brain function than those who had started smoking later in adolescence." One recent study even showed a drop in IQ. A thousand participants were given IQ tests at age 13 and then again at 38. An 8 point drop in IQ was found among the 38 year olds who had started regularly smoking pot by 18, with declines that persisted even if after they quit using a year later. Lead researcher, Madeline Meier, Ph.D., pointed out that "While 8 IQ points may not sound like a lot...a loss of IQ from 100 to 92 represents a drop from being in the 50th percentile to being in the 29th," a potential disadvantage for those teens for years to come. Dr. Staci Gruber, another researcher at McLean Hospital, found supportive evidence for these changes on the brain scan images of regular marijuana users. She believes early exposure possibly "changes the trajectory of brain development," especially in the frontal cortex white matter.
• Marijuana use and teenage driving: A survey of 2,300 eleventh and twelfth graders byStudents Against Destructive Decisions (SADD) found close to 20% of teens admitted to driving while high on marijuana, with more than 30% believing the drug doesn't distract them. A recent study of 50,000 motorists found those who smoked marijuana within three hours of driving had twice as many car accidents when compared to those who were sober. In another study, a third of drivers who were fatally injured tested positive for drugs, with marijuana at the top of the list. The combination of marijuana and alcohol was found to be worse than either substance alone. Stephen Wallace, senior adviser at SADD, worries about the recent statistics coming from studies on teens driving under the influence. "Marijuana affects memory, judgment and perception and can lead to poor decisions... .what keeps me up at night is that this data reflects a dangerous trend toward the acceptance of marijuana and other substances compared to our study of teens conducted just two years ago."

Parents may feel hypocritical lecturing their kids about marijuana, given their past experimentation with drugs when they were growing up. Or they may assume -- as they do about some other teenage behavior -- "this too shall pass." But it's important not to be lulled into looking the other way regarding the risks teens face today using marijuana. This is not the pot -- nor the counterculture -- that existed in the '60s, and our more lenient attitudes will only likely increase the prevalence and potency of what is out there today. While marijuana may, in fact, be a passing adolescent indulgence for some teens, there is enough research that suggests they face potential dangers that previous generations did not.

What do you think about marijuana use by teens today?