Nora Volkow, M.D., is the director of the National Institute on Drug Abuse (NIDA). The Challenge interviewed Dr. Volkow recently to discuss the research being conducted on drug abuse and its consequences on adolescent brains. The interview has been condensed for print. The full text can be found online at www.thechallenge.org.
NIDA spends a great deal of money on research studies to better understand and prevent drug abuse among children and adolescents. Why is so much attention placed on this period of the lifespan?
Adolescents warrant increased attention because they are at heightened risk for drug abuse, they may suffer more severe consequences, and childhood and early adolescence represent times when targeted prevention efforts may have the most impact. NIDA-supported research has shown that the earlier drug abuse is initiated, the more likely an individual will become addicted. In refact, addiction is called a developmental disease because it typically begins during the critical teen years when the brain is still developing—not to fully mature until a person is in his or her 20s. This heightened risk adolescents face, therefore, is far more than just a result of social angst or the opportunity to use drugs, though these factors certainly play a role. Rather, adolescents face increased risk because these environmental factors occur during a time of great change in the brain. For example, among the last areas of the brain to mature is the prefrontal cortex—the part of the brain that enables us to assess situations, make sound decisions, and keep our emotions and desires under control. The fact that this critical part of an adolescent’s brain is still a work-in-progress can help to explain the risk taking that is a characteristic of this time period, and can help us, as adults, recognize more fully the challenges youth face in making decisions that impact their health.
How do drugs affect brain functioning during childhood and adolescence?
It is important to understand that studies on brain functioning are still relatively new, especially in younger human populations. Innovative research, however, is helping to shed light on the various ways in which drugs can change the course of brain development and behavior. We know that drug abuse affects the brain circuitry involved in reward, motivation, memory, and judgment. Are these effects intensified when a still-developing brain is exposed to drugs? Likely so, given the range of mental and substance abuse problems already linked to early drug abuse. But recent studies are delving into how exposure to drugs at different points along a developmental trajectory changes the brain and leaves individuals more vulnerable to health problems later in life. This research is enhanced by the availability of new technologies, including neuroimaging tools that allow us to study the human brain like never before, literally to see into the brains of people and discover how drugs are affecting its function.
The most commonly used drugs among young people are alcohol, tobacco, and marijuana. Can use of these drugs during childhood and adolescence negatively affect brain functioning? If so, what are the long-term implications of such effects?
We have learned from our animal and human studies that observe behaviors, a proxy-measure for brain activity, that there are differences between adolescents and adults with regard to the effects of drugs. For example, findings from NIDA-sponsored animal studies suggest that adolescent rats become “addicted” to nicotine more readily, as they self-administered more often and in higher total doses per session than rats first exposed to nicotine as adults. This early exposure in rats also led to changes in a specific brain receptor that is important in promoting nicotine’s rewarding effects. Similar behavioral findings are emerging from our clinical research. Studies show that adolescents that smoke are more likely to become dependent on nicotine compared with adults and are also more likely than non-smoking adolescents to use other drugs. Findings, such as these, suggest that not only may smoking be more addictive if it is initiated during adolescence, but that it may heighten response to other addictive drugs.
In addition to nicotine, NIDA-supported research is also looking at how chronic marijuana use during adolescence alters brain function, particularly intellectual functioning, to see if there is an increased vulnerability with adolescents to cognition related changes. To take it a step further, we are studying the consequences of marijuana use on brain development to identify behavioral or cognitive “markers” for adolescents who progress from use to addiction. This research will help us to better understand why young people are particularly vulnerable to the consequences of drug abuse and how resulting brain changes may influence their overall development.
Methamphetamine use has garnered a lot of attention in the popular media. In 2004, 6.2 percent of high school seniors reported having used this drug at least once. How much use of methamphetamine is necessary before deleterious effects on the brain are apparent?
The short answer to your question is that no amount of methamphetamine is “safe.” The extent of the negative effects to the brain and how quickly those effects occur is based on many individual factors, such as genetics, environment, age, gender, amount and duration of use, and route of administration. Each of these factors, individually as well as combined, contributes to the harmful effects of any drug abused. Thus, it is possible that the consequences from the same amount of methamphetamine may differ significantly across individuals, thereby making it difficult, if not impossible, to quantify an amount of exposure at which the brain suffers long-term effects. Similarly, we cannot predict at what point in time or dosage an individual transitions from “controlled” drug abuse to compulsive addiction. That said, once a person starts using methamphetamine repeatedly, regardless of their initial vulnerability, the consequences can be devastating.
Acute consequences of the drug include cardiovascular problems and stroke, hyperthermia (elevated body temperature) and convulsions, and even death. Chronic methamphetamine abusers often exhibit signs of mental distress, including violent behavior, anxiety, depression, confusion, and insomnia. They also can also suffer from psychotic symptoms such as paranoia, auditory hallucinations, and delusions.
What other drugs should school staff be aware of?
In addition to methamphetamine, alcohol, nicotine, and marijuana, school staff should also be aware of the potential for adolescents to abuse inhalants, prescription drugs, and steroids. In the cases of inhalants and some prescription drugs, the substances are being used in a manner that is dissociated from their intended purposes, and therefore people often do not recognize their potential for abuse. Inhalants are particularly puzzling to adults since the idea of sniffing or snorting the fumes of paint-thinner, cooking spray, or nail polish remover is exceedingly unappealing. However, for a pre-teen or teen with limited access to traditional substances of abuse, inhalants present a means for a quick high that resembles that of alcohol inebriation (e.g. mild stimulations, loss of inhibitions, and distorted perceptions). Data from NIDA’s Monitoring the Future Study (a national survey of 8th-, 10th-, and 12th-graders) indicate that in 2005, approximately 17 percent of eighth graders reported ever trying an inhalant. These youths place themselves at risk for a bevy of negative consequences depending on which substance they use. Among them are: dementia, logical and cognitive abnormalities, memory loss, delusions, hallucinations, slurred speech, and loss of hearing or smell. The most serious effect is death, which can occur after even a single session of inhalant abuse, stemming from aspiration, accidental trauma, asphyxia, or cardiac arrythmias. Further, as with other drugs of abuse, inhalant abuse can progress into the chronic and relapsing disease of addiction and may further increase the risk of other drug abuse later in life.
Just as adults often do not consider their cleaning solutions under the kitchen sink to be potential substances of abuse, the items in their medicine cabinet are also overlooked. With recent data showing that one in 10 12th-graders reported nonmedical use of Vicodin within the past year, it is clearly time that we move past the perception that the nonmedical use of physician-prescribed drugs is not dangerous. In fact, consequences can be dire whether the adolescent is abusing the prescription drug for the intended purpose, for example as a sleep aide, pain reliever, anxiety reducer or, if they are abusing these drugs as a means of getting high. Stimulants, for example, can elevate blood pressure and cause irregular heartbeat, respiration, and seizures. Sleeping pills and other central nervous system (CNS) depressants, combined with any medication or substance that causes drowsiness, can slow both heartbeat and respiration, which can be fatal; discontinuing prolonged use of high doses of CNS depressants can cause seizures. Painkillers and antianxiety medications can cause depressed respiration and death. Further, the addiction to the prescription drugs is not only a facilitator of other negative consequences; it is itself, a negative consequence.
Finally, unlike traditional illicit drugs, prescription drugs can be abused in order to enhance performance or improve appearance. This opens the door for teens that might not otherwise abuse substances and yet, their need to lose weight or heighten their concentration in preparation for an exam, may lead them to adopt a “by any means necessary” approach. This challenges our notion of what an adolescent substance abuser is, and calls on school staff to learn to recognize the warning signs in students they might otherwise not consider at risk for drug abuse. The same holds true for those adolescents at risk for abusing anabolic steroids. Our recent data show that 2.6 percent of high school seniors reported using steroids at least once. While not as commonly abused as other types of drugs, the side effects of steroids can be particularly damaging to a group that is otherwise health conscience. Major side effects can include liver tumors and cancer, jaundice, high blood pressure, kidney tumors, severe acne, trembling, depression, and if severe enough, suicide. In males, steroids have a feminizing effect and in females, a masculinizing effect. Adolescents that abuse steroids face the possibility that their growth may be halted prematurely and permanently.
Research suggests that drug abuse involves multiple factors, including biology, environment, and interactions between the two. One salient environmental influence on children and adolescents is the school context. What are the most important factors in the school environment that either protect or put youths at risk for drug use?
Risk factors can occur at different stages of a child’s life, in different settings. Early onset risk factors can place children on developmental paths that lead to adolescent drug abuse and related problem behaviors. Within schools, several individual, peer, and environmental factors can place adolescents at risk for drug abuse: inappropriate classroom behavior, such as aggression and impulsivity; academic failure; poor social coping skills; and association with peers involved in high-risk behaviors, including drug abuse.
Not all risk factors, however, stem from the students themselves; in fact, misperceptions about the extent and acceptability of drug-abusing behaviors in school held by school staff and the public in general, also can create an environment that increases drug-abuse risk. For example, the belief that most adolescents use drugs when, in fact, most do not, can lead to ambiguous or poorly enforced drug-abuse policies.
The effects of these and other environmental risk factors can increase during transitions that occur in the school context—such as entrance to a new school, and transitions from elementary to middle school, or middle to high school. These are times when children and adolescents are faced with new academic and social situations. School-based prevention programs that show evidence for protecting adolescents from drug abuse are often integrated with goals for academic success and focus on promoting school bonding. In addition, they may improve social and academic skills; enhance peer relationships; improve self-control, coping skills and drug refusal skills; and correct misperceptions about adolescent drug-use norms. Finally, schools should use caution when grouping high-risk teens in peer group prevention programs, because such groupings have been shown to produce negative outcomes, as the youth may reinforce each other’s drug-abuse behaviors.
In addition, are there certain biological factors that may interact with school-related risk factors to heighten risk of drug abuse for some youth?
Clearly the more risk factors an adolescent has, the greater the likelihood that drug abuse will occur. School staff should take note of factors such as withdrawn or aggressive temperamental styles or early displays of aggression, poor impulse control, and otherwise unexplained academic problems. Among the most common biological risk factors for substance abuse are co-morbid mental conditions. Depression, anxiety, ADHD, and conduct disorder are often present in adolescents prior to their abusing drugs, perhaps as a form of self-treatment, but drug abuse itself may also trigger or worsen co-morbid mental conditions in some adolescents. In addition, biological and environmental risk factors in the family can increase risk for drug abuse in children and adolescents—such as a family history of drug or alcohol abuse, physical or sexual abuse, or neglect.
Finally, gender is a major factor in assessing risk status of adolescents for specific drugs. For example, while boys report significantly more drug use for most substances (especially alcohol and marijuana), adolescent females show an increased risk for abusing prescription drugs. While not a modifiable risk factor, gender should not be ignored when assessing risk and further, when developing and implementing prevention programs.
What are the three most important steps a school can take to help prevent drug abuse?
Three steps that schools can take are: Use science-based, proven prevention approaches that are developmentally appropriate and reinforced over time (e.g., provides booster sessions).
Implement interventions early, especially with children at early risk for aggression. Research has shown that early intervention can reduce problem behaviors and change negative developmental paths.
Create a school environment that emphasizes pro-social activity and responsibility for students, teachers, and administrators, and provides parent-family support.
For more information on prevention programs, I direct readers to the 2003 edition of NIDA’sPreventing Drug Abuse among Children and Adolescents: A Research-Based Guide for Parents, Educators, and Community Leaders. It is available to download at http://www.drugabuse.gov/pdf/prevention/RedBook.pdf
It offers prevention principles that can help parents, educators, and community leaders plan and deliver science-based prevention programs.
NIDA also maintains a Web site for teens that provides accurate information about drugs of abuse: http://www.teens.drugabuse.gov