Robert E. Morris
Use of alcohol, tobacco, and other illicit drugs (ATOD) by adolescents continues to be a major public health problem. In the short term, drug use is associated with significant adolescent morbidity and mortality. Early use of various substances is a strong predictor of both problem and lifelong use. Most adults with substance use disorders began using drugs as adolescents; hence much of the adult morbidity and mortality attributed to both legal (alcohol and tobacco) and illegal drug use can be traced to behaviors that began during adolescence. Alcohol, tobacco, and marijuana are the three drugs most abused by adolescents, although inhalant use is particularly common among younger adolescents. Other drugs wax and wane in popularity, their use following a predictable pattern. Drug “X” becomes popular, at least in part because it is presumed safe; as its use becomes more widespread, its negative effects become more widely known and its use increasingly perceived as risky. The popularity of drug “X” wanes, to be replaced by use of other presumably safer drugs. Decades later, due to the phenomenon known as generational forgetting, drug “X” again becomes popular, as knowledge of its side effects is no longer common knowledge. Recently, abuse of over-the-counter and prescription medications and their ready availability has emerged as a significant problem.
Advances in neuroimaging techniques and research using animal models of human puberty have elucidated the unique vulnerability of the still developing adolescent brain to the effects of alcohol and other drugs; many observed changes in response to drug use may be permanent (Goldstein and Volkow, 2002; Volkow et al., 2003; Chambers et al., 2003). Ongoing research into the brain's reward circuitry (e.g., the ventral tegmental area, the prefrontal cortex, and the nucleus accumbens) continues to demonstrate that in the brain, drugs of abuse share common pathways and exert their effects through similar mechanisms. For example, the active ingredient in marijuana, Δ9-tetrahydrocannabinol, stimulates the same µ1 opioid receptor as does heroin. Similarly, when rats that have been chronically exposed to a cannabinoid agonist are given a cannabinoid antagonist to produce an acute withdrawal state, they secrete elevated amounts of corticotropin-releasing factor. This same pattern is seen in withdrawal from other drugs of abuse. Given this growing body of research, drug addiction is best viewed as a chronic disease with relapses being common. However, recent data indicate that treatment of adolescents with drug problems is effective.
Middle and High School Youth
The best data on adolescent substance abuse come from the Monitoring the Future (MTF) study, conducted by the Institute for Social Research at the University of Michigan (www.monitoringthefuture.org). This school-based study began in 1975, surveying a nationally representative sample of 12th graders. Beginning in 1990, data about drug use by 8th and 10th grade students were added. Currently, the sample consists of approximately 50,000 youth. Because the anonymous surveys are conducted in schools, MTF data do not reflect drug use by out-of-school youth (including drop-outs, homeless, and incarcerated youth), whose use is typically higher.
The most important findings from the 2006 MTF survey, focusing especially on the last decade, are as follows:
and in 1997 for 12th graders and has declined since those peak years. In 2006, 30-day use was 8.1% among 8th graders, 16.8% among 10th graders, and 21.5% among 12th graders.
FIGURE 68.1 Trends in lifetime prevalence for an illicit drug use index for 12th graders. (From Johnston LD, O'Malley PM, Bachman JG, et al. Monitoring the Future national survey results on drug use, 1975–2006: Volume I, Secondary school students, NIH Publication No. 07–6205. Bethesda, MD: National Institute on Drug Abuse; 2007:229. Available at http://monitoringthefuture.org/pubs/monographs/vol1_2006.pdf.)
FIGURE 68.2 Trends in annual prevalence of an illicit drug use index for 12th graders. (From Johnston LD, O'Malley PM, Bachman JG, et al. Monitoring the Future national survey results on drug use, 1975–2006: Volume I, Secondary school students, NIH Publication No. 07–6205. Bethesda, MD: National Institute on Drug Abuse; 2007:230. Available at http://monitoringthefuture.org/pubs/monographs/vol1_2006.pdf.)
FIGURE 68.3 Trends in annual prevalence of an illicit drug use index across five populations. (From Johnston LD, O'Malley PM, Bachman JG, et al. Monitoring the Future national survey results on drug use, 1975–2006: Volume I, Secondary school students, NIH Publication No. 07–6205. Bethesda, MD: National Institute on Drug Abuse; 2007:60. Available at http://monitoringthefuture.org/pubs/monographs/vol1_2006.pdf.)
See Figure 68.6A–C and Table 68.1 for detailed information about drug use by adolescents in 2005.
Other surveys that track adolescent substance abuse to varying degrees are the Youth Risk Behavior Surveillance System (YRBSS), also administered in schools, (www.cdc .gov/HealthyYouth/yrbs/index.htm) and the National Survey on Drug Use and Health (NSDUH, www.oas.samhsa .gov/nhsda.htm). The latter survey, administered in the home setting, has the advantage of including out-of-school youth. However, as parents may be present at home during the survey, results may be subject to underreporting. This may explain why drug use estimates from the MTF surveys consistently yield higher estimates than does the NSDUH. According to the 2000 NSDUH, the average age of new drug users was 16 years for cigarettes, 16.2 for alcohol, 16.6 for marijuana, and 20.4 for cocaine.
FIGURE 68.4 Trends in 2-week prevalence of heavy drinking (five or more drinks in a row in the last 2 weeks) among 12th graders. (From Johnston LD, O'Malley PM, Bachman JG, et al. Monitoring the Future national survey results on drug use, 1975–2006: Volume I, Secondary school students, NIH Publication No. 07–6205, Bethesda, MD: National Institute on Drug Abuse; 2007:247. Available at http://monitoringthefuture.org/pubs/monographs/vol1_2006.pdf.)
FIGURE 68.5 Trends in 2-week prevalence of heavy drinking (five or more drinks in a row in the last 2 weeks) for 8th, 10th, and 12th graders. (From Johnston LD, O'Malley PM, Bachman JG, et al. Monitoring the Future national survey results on drug use, 1975–2006: Volume I, Secondary school students, NIH Publication No. 07–6205. Bethesda, MD: National Institute on Drug Abuse; 2007:241. Available at http://monitoringthefuture.org/pubs/monographs/vol1_2006.pdf.)
Nonmedical Use of Prescription Medications
One worrisome new trend in adolescent drug abuse is nonmedical use of prescription medications (pain relievers, stimulants, tranquilizers, and sedatives). According to the NSDUH, 11.4% of 12- to 17-year-olds surveyed in 2004 had ever abused prescription pain relievers, with 7.4% using them in the last year, and 3% in the last month (http://www.oas.samhsa.gov/NSDUH/2k4nsduh/2k4tabs/Sect1peTabs1to18.pdf). The largest group of new drug users was those who began using prescription pain relievers without a physician's prescription. According to the most recent Partnership for a Drug Free America Tracking Survey, 18% of teenagers have ever used hydrocodone (Vicodin), and
10% have used oxycodone (OxyContin), methylphenidate (Ritalin), or dextroamphetamine/amphetamine (Adderall) without a physician's prescription. Approximately 28% of teens in this survey indicated that these drugs were “very easy” to get, as compared to 48% who felt the same about marijuana and 14% about ecstasy (http://www.drugfree.org/Portal/DrugIssue/Research/PATS_Teens_2004_Report/Teens_Abusing_Rx_and_OTC_Medications). The 2005 MTF data demonstrate that hydrocodone use has declined slightly among 8th, 10th, and 12th graders since 2003. In contrast, annual use of oxycodone from 2002 to 2006 has increased steadily, although nonsignificantly, among 8th graders; remained largely unchanged among 10th graders; and decreased significantly between 2005 and 2006 among 12th graders (from 5.5% to 4.3%).
The European School Survey Project on Alcohol and Other Drugs (ESPAD), conducted in 2003 in 36 European countries and regions among 15- to 16-year-old students
(mean age 15.8 years), permits comparisons of alcohol use between the United States, where the legal age for alcohol consumption is 21 years, and European countries, most of whom have legal drinking ages below 21. As shown in Figures 68.7 and 68.8, compared to students comprising the 2003 MTF survey cohort, adolescents in most of these countries/regions drink more heavily than do U.S. adolescents and are more likely to be intoxicated (www.udetc.org/documents/CompareDrinkRate.pdf, accessed 12/08/05).
FIGURE 68.6 A: 8th graders; B: 10th graders; and C: 12th graders. Prevalence and recency of use of various types of drugs for 8th, 10th, and 12th graders, 2006. B, C: Annual use not measured for cigarettes and smokeless tobacco. LSD, lysergic acid diethylamide; MDMA, methylenedioxymethamphetamine. (From Johnston LD, O'Malley PM, Bachman JG, et al. Monitoring the Future national survey results on drug use, 1975–2006: Volume I, Secondary school students, NIH Publication No. 07–6205. Bethesda, MD: National Institute on Drug Abuse; 2007:136–137. Available at http://monitoringthefuture.org/pubs/monographs/vol1_2006.pdf.)
College Students and Their Noncollege Peers
Although most college students and their noncollege peers cannot legally purchase alcohol, the vast majority have used it. Approximately 82% of college students and 79% of noncollege peers have used alcohol in the last year, with 61% of noncollege adolescents and approximately 65% of college students consuming it in the last 30 days. These 30-day use patterns have remained relatively constant over the last decade. Binge drinking among college students (defined as five or more drinks in a row in the prior 2 weeks) has attracted considerable attention. On this measure, college students clearly drink more than their noncollege peers and male college students drink considerably more than female college students. However, the gap between males and females has narrowed somewhat in the last decade (Figs. 68.9 and 68.10).
Binge drinking is especially problematic because of its association with poor academic performance, violence, sexual assault, and unprotected sexual intercourse. According to the Harvard School of Public Health College Alcohol Survey, binge drinking affects not only those who consume alcohol and their partners but other students on campus as well. Nonbinge drinking students on campuses with medium to high levels of binge drinking are more likely to report having been pushed, hit, assaulted, or having been the victim of a sexual assault/date rape than similar students on campuses with low levels of binge drinking (Wechsler and Nelson, 2001).
Use of illicit drugs in the last 12 months among college and noncollege students reached a low point in 1991 and then began to trend upward, reaching a peak in 2001 (Fig. 68.3). Since then, rates of illicit drug use have remained largely unchanged among college students although increasing somewhat among noncollege students. After alcohol, marijuana is the drug most often used by both college and noncollege students.
Other notable findings regarding drug use in last 12 months are as follows:
See Figures 68.3, 68.9, and 68.10 and Tables 84.1, 84.2, 84.3, 84.4, 84.5, 84.6, 84.7, 84.8, 84.9 for more detailed data about drug use by college students and noncollege adolescents.
Long-Term Outcomes of Drug Use
Over the last 5 years, a number of studies provide evidence that use of drugs, especially if initiated in early to mid-adolescence, is associated with significant long-term adverse consequences:
more heavily at age 16 (>7 units/week with 1 unit equal to one small glass of wine) were 1.64 times more likely than light drinkers to binge at age 42. Levels of binge drinking at age 23 increased the odds of binge drinking at 42 (odds ratio 2.10 for men and 1.56 for women) (Jefferis et al., 2005).
FIGURE 68.7 Prevalence of heavy drinking in the last 30 days: United States and Europe. (From youth drinking rates and problems. A comparison of European Countries and the United States. Office of Juvenile Justice and Delinquency Prevention. Available at www.udetc.org/documents/CompareDrinkRate.pdf [accessed 12/12/05].)
Risk and Protective Factors for Drug Use
At a population level, there is a strong link between adolescents' perceptions of the risks of drug use and the prevalence of use. For example, over the last 30 years, the prevalence of marijuana use rose and fell according to how risky its use was perceived to be by adolescents. The percentage of 12th graders who perceived “great risk” in regular marijuana use reached a nadir (~35%) in 1979. In that same year, reported use of marijuana in the last year by 12th graders peaked at approximately 50%. Perceived risk of regular use then began to rise, peaking in 1992. Not surprisingly, use in the last 12 months fell to its lowest level at the same time. Perceived risk then began to fade and use began to rise. In contrast, measures of availability (that a drug is “fairly easy” or “very easy” to get) and disapproval bear little relation to use patterns (Fig. 68.11).
Similarly, use of ecstasy began climbing steeply in 1998. In 2001, the proportion of 12th graders who perceived great risk in use of this drug increased and in 2002, use began to fall. Over the next 2 years, use continued to decrease as the perception that ecstasy use was risky increased.
One major protective factor associated with drug use is race/ethnicity. Since the MTF survey began in 1975, African-American 12th graders have consistently had lower rates of illicit drug use than white youth, with Hispanic youth having rates in-between those of African-Americans and whites. African-American 8th and 10th graders also have lower rates of illicit drug use than their white classmates although the differences are less pronounced than among 12th graders. In 2004, Hispanic 8th and 10th graders had higher rates of drug use than did whites.
Adolescent drug use is a complex phenomenon; no single risk factor, when present, predicts with certainty
that an adolescent will use drugs or develop a substance abuse problem, nor does the presence of a single protective factor offer complete reassurance that no use will occur. Rather, drug use or nonuse results from a combination of these factors. Risk and protection can exist at the individual, peer, family, school, and community level or domain (Hawkins et al., 1992). These are outlined in Table 68.2.
FIGURE 68.8 Prevalence of intoxication in the last 30 days: United States and Europe. (From youth drinking rates and problems. A comparison of European Countries and the United States. Office of Juvenile Justice and Delinquency Prevention. Available at www.udetc.org/documents/CompareDrinkRate.pdf [accessed 12/12/05].)
FIGURE 68.9 Alcohol: Trends in 2-week prevalence of five or more drinks in a row among college students versus others, 1 to 4 years beyond high school. (From Johnston LD, O'Malley PM, Bachman JG, et al. Monitoring the Future national survey results on drug use, 1975–2006: Volume II, College students and adults ages 19–45, NIH Publication No. 07–6206. Bethesda, MD: National Institute on Drug Abuse; 2007:277. Available at http://www. monitoringthefuture.org/pubs/monographs/vol2_2006.pdf.)
FIGURE 68.10 Alcohol: Trends in 2-week prevalence of five or more drinks in a row among male versus female college students. (From Johnston LD, O'Malley PM, Bachman JG, et al. Monitoring the Future national survey results on drug use, 1975–2006: Volume II, College students and adults ages 19–45, NIH Publication No. 07–6206. Bethesda, MD: National Institute on Drug Abuse. Available at http://www.monitoringthefuture.org/pubs/monographs/vol2_2006.pdf.)
FIGURE 68.11 Marijuana: Trends in the perceived availability, perceived risk of regular use, and prevalence of use in last 30 days for 12th graders. (From Johnston LD, O'Malley PM, Bachman JG, et al. Monitoring the Future national survey results on drug use, 1975–2006: Volume I, Secondary school students, NIH Publication No. 07–6205. Bethesda, MD: National Institute on Drug Abuse; 2007:379. Available at http://monitoringthefuture.org/pubs/monographs/vol1_2006.pdf.)
Adolescent Brain Development and Susceptibility to Drug Use and Drug-Associated Brain Damage
Use of sophisticated imaging techniques demonstrates that adolescence is a period of significant brain development (Sowell et al., 1999, 2001; Horská et al., 2002). In a longitudinal study of 145 healthy children (56 females, age range 4.2–21.6 years), Giedd et al. (1999) noted the following changes:
Studies in rats show that mesolimbic dopamine (DA) synthesis in the nucleus accumbens is lower in preadolescent than adolescent rats, which in turn is lower than in adult rats. Turnover rates for DA are also lower in younger rats as compared with adult rats. Dopaminergic and noradrenergic systems show large increases in neurotransmitter levels and activity during adolescence, particularly in the midbrain and hippocampus. The hippocampus increases significantly in size. The mesolimbic system (which projects from the ventral tegmental area to the nucleus accumbens) may mediate behavioral changes in adolescents and has been shown to play a large role in the reward circuitry of the brain that fuels drug addiction. The hippocampus is intricately involved with new memory formation, a critical process in learning.
Given the significant brain changes that occur during adolescence, including frontal lobe changes linked to impulse control and decision making, and the areas involved in the brain's reward circuitry, it is not surprising that adolescents may be uniquely susceptible to the harmful effects of drug use, including dependence or addiction. Several studies provide clear evidence for this susceptibility; although a few studies have been conducted in humans, for ethical reasons most data derive from studies in rats.
of the ligand-gated acetylcholine receptors in the ventral tegmental area of the brain (Adriani et al., 2003).
Stages of Drug Use
It is clinically useful to conceptualize adolescent substance abuse as occurring across a continuum of use. Use generally proceeds from one stage to the next, although some adolescents may skip stages (adapted from MacDonald, 1984).
Early efforts at prevention of drug use by adolescents were based on the assumption that use was driven by inadequate knowledge of the harmful effects of drug use. Evaluation of these programs failed to show an effect; indeed, some studies showed an increase in use following presentations on the effects of various drugs. Other efforts relied on the use of authority figures (e.g., police) to deliver antidrug messages. These, too, failed to show an effect (Ennett et al., 1994).
Beginning in the 1980s, prevention efforts became much more sophisticated, recognizing the multiple individual, familial, peer, school, and community factors that bear on use of drugs by adolescents. Given the uptake of drug use by 8th graders (and even earlier for some), these efforts targeted youth before or during junior high school.
Some prevention programs, usually school-based, focus on a “life skills” approach to target numerous risk factors for ATOD use. Such programs generally have the following components (Botvin and Kantor, 2000):
Such programs require considerable resources to implement. Typically, they use a highly structured curriculum taught over 15 classroom sessions by trained facilitators (not simply classroom teachers). Although some material is didactic, many sessions require role-playing, skills rehearsals, feedback, and homework to practice and reinforce the skills learned in class. In some studies, booster sessions delivered in subsequent years are essential to the program's initial effects at reducing drug use or maintaining the gains as students grow older. Numerous studies have demonstrated that this kind of approach does reduce ATOD use, both in the short and long term. For a comprehensive review of drug prevention programs, see the reviews by Faggiano et al. (2005) and by Skara and Sussman (2003).
A second approach is to target the early antecedents of risk factors for substance abuse. For example, Hawkins et al. (1999) found that fifth grade students in high crime areas of Seattle who participated in a program that included training for teachers, parenting classes for parents, and social competence training for students, had lower levels of heavy drinking at 18 years than did control students. In another study, Kellam and Anthony (1998) reported that aggressive/disruptive boys assigned to a 2-year intervention (during grades 1 and 2) aimed at improving behavior in the classroom had lower rates of smoking initiation in early adolescence than did boys in the usual classroom group.
A third approach targets a variety of community approaches including those aimed at policy changes and also media campaigns. These include strict enforcement of laws prohibiting sale of alcohol and tobacco products to minors, counter advertising campaigns, and media criticism. For example, in 1998 the Florida Tobacco Control Program launched a statewide program that included enforcement of regulations against the sale of tobacco to minors and a “truth” counter marketing campaign that sought to counter the tobacco industry's purposeful attempts to market cigarettes to teenagers (“Our brand is truth, their brand is lies”). After 2 years, current cigarette use dropped from 18.5% to 12.1% among middle school students and from 27.4% to 22.6% among high school students. Prevalence of never use increased significantly and prevalence of experimentation decreased significantly. Subsequent analyses showed that the media campaign played a significant role in the program's success (Bauer et al., 2000; Sly et al., 2001; Niederdeppe et al., 2004).
For Teenagers and Parents
http://www.drugfree.org/. Home page for the Partnership for a Drug Free America. Has comprehensive resources for parents, teenagers, and professionals.
http://camy.org/. Home page of the Center on Alcohol Marketing and Youth. Contains resources to examine and counter the marketing of alcohol to youth.
http://www.freevibe.com/. A youth oriented site developed by the ONDCP.
http://www.nida.nih.gov/students.html. A Web site maintained by NIDA for adolescents, especially for those in grades 5 to 9.
For Health Professionals
http://www.monitoringthefuture.org/. Home page for the MTF survey with links to new press releases and previous research documents.
http://www.cdc.gov/HealthyYouth/yrbs/index.htm. Home page for the CDC's Youth Risk Behavior Surveillance System.
http://www.oas.samhsa.gov/nhsda.htm. Home page for the National Survey on Drug Use and Health.
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