Adolescent Health Care: A Practical Guide
Adolescent Substance Use and Abuse
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:
- Drug use among 8th graders has decreased by approximately one third since 1996, the peak year in the last decade. Since 1997, the peak year for 10th and 12th graders, drug use is down by 25% and 10%, respectively. For the fifth consecutive year (2002–2006), the proportion of 10th and 12th grade students who use illicit drugs declined (www.monitoringthefuture.org).
- Lifetime use: Use of illicit drugs by 12th graders peaked in 1980 to 1982 and then steadily declined until 1992 when use began to increase again (Fig. 68.1). Lifetimeuse of illicit drugs among 8th grade students peaked in 1996 and has declined since then. Lifetime use among 10th and 12th graders peaked in 1997 to 1999, declining since then. In 2006, 20.9% of 8th graders, 36.1% of 10th graders, and 48.2% of 12th graders had ever used an illicit drug.
- Annual use (last year): Use of any illicit drug peaked in 1996 for 8th graders and in 1997 for 10th and 12th graders, declining in each year thereafter. In 2006, 14.8% of 8th graders, 28.7% of 10th graders, and 36.5% of 12th graders had used an illicit substance in the last year (Figs. 68.2 and 68.3).
- Thirty-day use(i.e., use in the 30 days before the survey) of illicit drugs peaked in 1996 for 8th and 10th graders
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.)
- Daily use: In 2006, 1% of 8th graders, 3.1% of 10th graders, and 2.8% of 12th graders reported smoking marijuana or hashish daily; 0.5% of 8th graders, 1.4% of 10th graders, and 3.0% of 12th graders reported drinking alcohol daily. Four percent, 7.6%, and 12.2% of 8th, 10th, and 12th graders, respectively, reported daily cigarette smoking.
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.)
- Alcoholcontinues to be the drug most abused by adolescents. In 2006, approximately 33.6% of 8th graders, 55.8% of 10th graders, and 66.5% of 12th graders had used alcohol in the last year. Binge drinking (defined as five or more drinks in a row) was reported by 10.9% of 8th graders, 21.9% of 10th graders, and 25.4% of 12th graders in the 2 weeks before the survey. Binge-drinking rates have decreased steadily among 8th graders from 1999 to 2005 but there was small increase in 2006; they have remained essentially unchanged since 2002 among 10th and 12th graders, with small nonsignificant decreases occurring from 2004 to 2006. Although males drink more heavily than females, the gap has recently narrowed (Figs. 68.4 and 68.5).
- Marijuana: After alcohol (legal for those aged 21 and older) and tobacco (legal for teenagers aged 18 and older), marijuana is the illicit drug most used by 10th and 12th graders. Among 8th graders, inhalants (17%) and marijuana (16%) are used almost equally. In 2006, 6.5% of 8th graders, 14.2% of 10th graders, and 18.3% of 12th graders reported using marijuana or hashish in the last 30 days (Fig. 68.6A–C).
- “Ecstasy” (methylenedioxymethamphetamine or MDMA) use climbed steeply from 1998 to 2001, then began to decline in 2002 with a small increase 2006; perceived risk of use began increasing in 2001.
- Methamphetamine: Annual use of methamphetamine decreased significantly from 2003 to 2004 among 8th graders but showed a nonsignificant increase in 2005; over the same period, an insignificant decrease was observed among 10th graders. Annual use of methamphetamine decreased significantly among 12th graders from 2004 to 2005 (from 3.4%–2.5%).
- Steroid use: Eighth graders have shown a decline in steroid use since 2000 (but none from 2004–2005); a decline among 10th graders has been occurring since 2002. Twelfth graders demonstrated a significant decline in use from 2004 to 2005 (from 2.5%–1.5% use in the last year).
- Rohypnol/GHB: Use of Rohypnol and GHB among all three grades is low (1.6% or less). Annual use of Rohypnol has shown an upward trend among 8th graders since 2002 but has remained essentially unchanged among 10th and 12th graders since 2002. Annual use of GHB declined among 12th graders from 2004 to 2006 but remained stable among 8th and 10th graders.
- Inhalants: Lifetime use of inhalants showed a significant increase from 2003 to 2004 and a nonsignificant decrease from 2005 to 2006 for 8th graders; annual use of inhalants decreased among 8th graders from 2002 to 2006. From 2003 to 2006, annual use has shown nonsignificant decreases among 10th and 12th graders.
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:
- MDMA (“ecstasy”) use grew rapidly in popularity among college students, with peak use occurring in 2001 and declining rapidly after that.
- Use of narcotics other than heroin has shown a steady upward trend since 1992 and leveling out since 2004.
- Cocaine use reached a nadir in 1994. Among college students, rates of use plateaued from 2000 to 2002 and then increased in 2003 and 2004 with a slight decrease in 2005 and 2006. Among noncollege students, rates of use increased through 2004 and have remained almost level since that time.
- In 2006, approximately 7.6% of college students and 9.1% of noncollege students reported nonmedical use of hydrocodone (Vicodin) in the last 12 months. This is a slight decline from 2005 following increases since 2002 when this was first measured. Data from the 2001 Harvard School of Public Health College Alcohol Survey indicate that the prevalence of nonmedical use of prescription opioids and stimulants was 7% and 4.1%, respectively (McCabe et al., 2005a, b).
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:
- A retrospective cohort study from Sweden showed that, compared to those who never smoked marijuana those who smoked a total of 11 to 50 times were 2.2 times likely to develop schizophrenia; the risk was 3.1 times for those who smoked more than 50 times. After controlling for use of other drugs, those who smoked marijuana more than 50 times were 8.7 times more likely to develop schizophrenia whereas those who smoked less than 50 times were no longer at increased risk (Zammit et al., 2002).
- A longitudinal study from New Zealand showed that, controlling for childhood psychotic symptoms and other drug use, those who smoked marijuana by age 15 were 7.2 times more likely to develop schizophrenia symptoms at age 26 than controls (Arseneault et al., 2002).
- Another longitudinal birth cohort study from New Zealand also demonstrated that cannabis use, especially by age 14 to 15, was significantly related to depression, suicidal ideation and attempts, and participation in violent crimes at age 21, even after controlling for a wide variety of potential confounders (Fergusson et al., 2002).
- A study of 1,600 Australian students aged 14 to 15 followed for 7 years demonstrated that weekly use of cannabis among females predicted an almost twofold increase in risk for depression and anxiety at age 21 to 22. In contrast, preexisting depression and anxiety did not predict later cannabis use (Patton et al., 2002).
- Data from the National Longitudinal Survey of Youth show that binge drinking during adolescence (ages 17–20) is associated with a relative risk of 2.3 for men and 3 for women for binge drinking at age 30 to 31 (McCarty et al., 2004).
- A population-based cohort study in England, Scotland, and Wales demonstrated that men who drank
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).
- A cohort study from Australia followed almost 2,000 teenagers from age 14 to age 21, measuring drinking behaviors yearly. Frequent drinking at least once during the 7 years was associated with a twofold increase in the risk for being diagnosed with alcohol dependence at age 20; frequent drinking during more than one period increased the risk threefold. Smoking marijuana weekly or more at one or more times was also associated with an increased risk for being diagnosed as alcohol dependent at age 20 (Bonomo et al., 2004).
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
- Perception of risk
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.
- Other risk/protective factors
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:
- Linear increases in white matter volume, with greater changes in males than females. The net increase across age 4 to 22 was 12.4%. Increases did not vary by brain region. These changes likely reflect increased myelinization.
- Gray matter volume changes were nonlinear and varied by lobe. Frontal lobe gray matter increased during early adolescence, reaching peak size at 11 years for females and at 12.1 years for males. Parietal lobe gray matter volume peaked at 10.2 years for females and at 11.8 years for males. Temporal lobe gray matter peaked at 16.5 years for males and at 16.7 years for females. In all three lobes, volumes then decreased. Occipital lobe gray matter continues to increase during adolescence without any leveling off. One explanation for these changes is an initial increase followed by a decrease in the number of synapses in the brain; increased myelinization may also contribute.
- Observed changes in the frontal cortex are consistent with neuropsychological studies that show that frontal lobes are involved with emotional regulation, planning, organizing, and response inhibition (the latter three constituting “executive functioning”).
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.
- Compared with adult rats, adolescent rats are less susceptible to the sedative properties of alcohol and the onset of sedation is slower (Li et al., 2003). This phenomenon may be explained by data showing that cells from adult rats display greater ethanol-induced GABAAreceptor–mediated inhibitory postsynaptic currents than do cells from juvenile or adolescent rats. If this effect were true in humans, then adolescents would be less likely than adults to naturally curtail their intake on the basis of sedation.
- In contrast to younger or older rats, adolescent rats displayed a lack of alteration in dopamine and 3,4-dihydroxyphenylacetic acid metabolism with repeated exposure to ethanol. This suggests that adolescents may fail to adapt to repeated alcohol use or may adapt in a way that results in increased reactivity to ethanol (Philpot and Kirstein, 2004).
- Adolescent rats are much more vulnerable than adult rats to alcohol-induced learning impairments. Owing to ethical and legal constraints, similar experiments cannot be reproduced in adolescents. However, after ingesting 2 to 3 drinks, young adults in their early twenties display a greater degree of impairment on tasks involving immediate and delayed recall than do young adults in their late twenties who consume the same amount of alcohol (Monti et al., 2005).
- After exposure to levels of alcohol consistent with a binge-drinking episode, adolescent rats display greater damage than adult rats to the frontal association cortex and the anterior piriform and perirhinal cortices (which correspond to the orbital-frontal and temporal-cortical areas in humans). Adult rats exposed to binge drinking during adolescence display microglia and long-term changes in serotonergic innervation as compared with control rats (Monti et al., 2005).
- Ironically, adolescents display less motor impairment than adults given comparable amounts of ethanol ingestion (White et al., 2002). This is particularly striking given the fact that adolescents have higher peak brain ethanol levels than adults following ethanol administration.
- Adolescents who smoke cigarettes daily have impairments in working memory compared to nonsmokers, even after controlling for general intelligence, reading achievement, parental education, baseline affective symptoms, and lifetime exposure to alcohol and marijuana. The impairments are more pronounced the younger the age of initiation of smoking is and the severity of impairment at least temporarily increases with smoking cessation. (Jacobsen et al., 2005).
- Rats exposed to nicotine in the peribut not postadolescent period of development become more sensitive to the reinforcing properties of nicotine during adulthood. This is manifested by increased self-administration of nicotine in adulthood and an increase in gene expression of specific subunits
of the ligand-gated acetylcholine receptors in the ventral tegmental area of the brain (Adriani et al., 2003).
- In rats, exposure to nicotine during the periadolescent period (at nicotine levels comparable to that of smokers) is associated with a “profound activation” of midbrain catecholaminergic pathways, followed by a loss of response to an acute nicotine challenge (receptor desensitization). More than 30 days after the last exposure, these rats again showed significant activation of the catecholaminergic pathways with exposure to nicotine. Female rats showed significant late onset cell damage and loss in the hippocampus (Trauth et al., 2001).
- Marijuana, cocaine, and amphetamines
- In both adolescent and adult rats, repeated exposure to the cannabinoid agonist WIN55212.2 (WIN) produced tolerance to its effects. However, adolescent but not adult rats exposed to WIN later displayed long-lasting cross-tolerance to morphine, cocaine, and amphetamines, suggesting a heightened sensitivity to psychoactive substances during a period of brain immaturity (Pistis et al., 2004).
- Chronic exposure of periadolescent but not post-weanling or adult rats to cocaine and amphetamine results in upregulation of the transcription factor ΔFosB in the nucleus accumbens (Ehrlich et al., 2002).
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).
- Stage 0: No drug use. The adolescent is not subject to any health risks posed by his/her own use of illicit substances, although he/she is still subject to risks from use of drugs by friends (e.g., riding with an impaired driver; sexual assault in association with a date rape drug; as a victim in a fight with an intoxicated individual). For clinicians, the primary focus for these adolescents is on safety, praising and normalizing abstinence, and prevention (refusal skills).
- Stage 1: Experimentation. Adolescents at this stage may try various drugs, typically out of curiosity or to fit in with friends. The most commonly used drugs are alcohol and tobacco; some may use only marijuana. Once an adolescent crosses from Stage 0 to Stage 1, he/she places himself at risk from the health risks associated with illicit drug use. Even a single episode or very sporadic drug use can involve significant risk—even death—depending on the circumstances of use and the drug(s) used. Some adolescents may move from Stage 1 back to Stage 0, having found the experience unpleasant. For clinicians, the primary focus should be on reviewing risks from drug use, safety, encouraging and normalizing abstinence, and rehearsal of refusal skills.
- Stage 2: Learning the mood swing. At this stage, the adolescent will continue to experiment with drugs if available but will not make a concerted effort to obtain the drugs; types of drugs used will increase. Use typically occurs in social settings and positive/pleasurable experiences generally outweigh negative consequences, although the latter may occur. Use typically occurs on the weekends. Significant changes in behavior are not readily apparent although the adolescent may need to change his/her behavior to hide use from parents. For clinicians, the primary focus should be on assessing the adolescent for risk factors associated with progression, reviewing risks, safety, encouraging and normalizing abstinence, and refusal skills.
- Stage 3: Seeking/preoccupation with the mood swing. As they progress to this stage, adolescents will actively seek out drug use and begin to organize their lives around assuring a supply of drugs. They will actively seek out settings where drugs are likely to be used and avoid ones where drug use is unlikely. They may buy or even sell drugs to assure a supply. The types of drugs used continue to expand. The social network will largely consist of drug using peers. Straight friends may be dropped. Depending on the types of drugs used and the extent of use, behavioral changes may become apparent. Negative consequences associated with drug use will increase and the adolescent will need to be increasingly vigilant to hide drug use from parents. For clinicians, the focus should be on reviewing risks, safety, assessing for problem use, and challenging the adolescent's perception that he/she controls his/her drug use (abstinence challenges/contracts). Adolescents at this stage need careful follow-up and some will meet the criteria for substance dependence or abuse. Involvement of parents may be necessary despite protestations from the adolescent.
- Stage 4: Problem use/dependence. The hallmark of this stage is continued use of drugs despite experiencing significant negative consequences. Adolescents in this stage will often use drugs in order to feel norma Any adolescent in this stage requires a comprehensive evaluation and will need intensive treatment. Most, if not all, adolescents at this stage will meet criteria for substance dependence or abuse.
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.
- Life skills approach
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):
- ATOD-related information and skills: Information about the short and long-term health risks of ATOD use; providing information about the actual prevalence of ATOD use by adolescents in the community; providing information about the decrease in acceptability of ATOD use among adolescents; refusal skills to resist pressure to use drugs.
- Personal self-management skills: Improve decision making and problem solving; skills to analyze, interpret, and resist media influences; teaching skills to cope with emotions such as anxiety, frustration, and anger; teaching personal behavior change and self-management skills.
- Social skills: This component is aimed at improving students' social competence (teaching how to initiate conversations, verbal and nonverbal assertive skills, communicating with others, skills related to male–female relationships).
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).
- Risk factor reduction
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.
- Community-based approaches including policy changes and media campaigns
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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