Epidemiology of Youth Drug Abuse

Research Findings from February, 2003 Director's Report

This section lists selected summaries from NIDA funded research projects that investigate the epidemiology, etiology, and prevention research. The summaries provided were selected from recent issues of the Director's Report to the National Advisory Council on Drug Abuse. For a more comprehensive listing of NIDA funded projects see the Director's Report.

Ketamine Injection among High Risk, Street Involved Youth in New York City

Using ethnographic methods, investigators examined 25 young ketamine injectors in New York City. The following practices associated with ketamine injection were identified as risk factors for viral transmission of bloodborne pathogens, such as HIV, HBV, and HCV: (1) ketamine was typically injected in a group setting with up to 10 other injectors; (2) it was typical to inject multiple times, such as 8-10 times over several hours; (3) over half of the participants reported some form of paraphernalia sharing, including syringes and bottles; (4) a large proportion of participants received syringes from indirect sources; and (5) ketamine was frequently obtained for free which often led to spontaneous injection events. Their findings also suggest that, although ketamine is classified as a "club drug," the injection of ketamine occurs in a variety of settings and is typically injected and experienced apart from the club and rave scenes. The investigators conclude that ketamine injection is an emerging trend among hidden populations of injection drug users, particularly among high risk, street-involved youth. Lankenau, S.E. and Clatts, M.C. Ketamine Injection among High Risk Youth: Preliminary Findings from New York City. Journal of Drug Issues, 32, pp. 893  905, Summer 2002.

Monitoring the Future Study

The results from the 2002 annual Monitoring the Future (MTF) survey of 8th, 10th, and 12th grade students in U.S. schools were released in December 2002. The findings indicate that use of marijuana, several other illicit drugs, cigarettes and alcohol decreased from 2001 to 2002. The percentages of 8th and 10th graders using any illicit drug declined and were at their lowest level since 1993 and 1995, respectively. Marijuana use decreased among 10th graders; LSD use was down among students in each grade; and MDMA (Ecstasy) use decreased in each grade, though declines were statistically significant only for 10th graders. Use of most other drugs, including cocaine and heroin, remained stable. No major drug use indicators increased. Cigarette smoking decreased in each grade, expanding on a recent trend. Alcohol use and having "been drunk" were down among 8th and 10th graders, and binge drinking decreased among 10th graders.

Attitudes toward substance use, often seen as harbingers of change in rates of use, were mostly stable, but both perceived risk of harm from using MDMA and disapproval of using this drug increased in each grade. Perceived availability of LSD was down in each grade, and perceived availability of alcohol and cigarettes decreased in grades 8 and 10.

Monitoring the Future, which is conducted by the University of Michigan under a grant from NIDA, has been tracking drug use among seniors for 28 years and among 8th and 10th graders since 1991. The 2002 sample consisted of around 43,700 students in 394 schools in the coterminous U.S.

The changes noted below are statistically significant unless otherwise indicated.

Marijuana

• Among 10th graders, marijuana/hashish use in the past year and past month decreased and daily use in the past month was down. Past year use decreased from 32.7 percent to 30.3 percent; past month use went from 19.8 percent to 17.8 percent, and daily use in the past month declined from 4.5 percent to 3.9 percent.
• For the 8th graders, there has been slow but steady progress toward reduction of marijuana use. The past year marijuana use rate for 8th graders in 2002 -- 14.6 percent -- is the lowest rate seen since 1994, and well below the recent peak of 18.3 percent in 1996.

• Cocaine use remained statistically unchanged from 2001 to 2002 for each grade and recency period. Past year cocaine use was reported by 2.3 percent of 8th graders, 4.0 percent of 10th graders, and 5.0 percent of 12th graders.
• This comes after declines in cocaine use among 10th graders from 2000 to 2001 and among 12th graders between 1999 and 2000.
• Crack use showed a significant increase in past year use among 10th graders, returning to around its 2000 level following a decline in 2001.

• Heroin use by 8th, 10th and 12th graders remained stable from 2001 to 2002 following a decline from 2000 to 2001 among 10th and 12th graders. Past year use rates were around 1 percent in each grade.
• New questions on nonmedical use of Oxycontin and Vicodin in the past year were added in the 2002 survey for each grade, and the findings give some reason for concern.
• Oxycontin use in the past year without a doctor's orders was reported by 1.3 percent of 8th graders, 3.0 percent of 10th graders, and 4.0 percent of 12th graders.
• Nonmedical use of Vicodin in the past year was reported by 2.5 percent of 8th graders, 6.9 percent of 10th graders, and 9.6 percent of 12th graders.

• Inhalant use in the lifetime decreased among 8th and 10th graders and past use decreased among 8th graders. Lifetime use went from 17.1 percent in 2001 to 15.2 percent in 2002 among 8th graders and from 15.2 percent to 13.5 percent among 10th graders.
• In 2002, inhalant use among 8th and 10th graders in all recency periods was the lowest seen in the history of the survey and the lowest in about 20 years for seniors.

• Hallucinogen use in the lifetime, past year, and past month declined for 12th graders, and past year use was down among 10th graders.
• LSD showed major changes from 2001 to 2002. Rates of use decreased markedly in each grade and recency period. Past year use, for example, declined from 6.6 percent to 3.5 percent among 12th graders, from 4.1 percent to 2.6 percent among 10th graders and from 2.2 percent to 1.5 percent among 8th graders. These are the lowest rates of LSD use in the history of the survey for each grade.

• Rates of MDMA (Ecstasy) use decreased significantly among 10th graders. For this grade, past year use declined from 6.2 percent to 4.9 percent and past month use went from 2.6 percent to 1.8 percent. Use by 8th and 12th graders also showed signs of decline.

• Cigarette use declined in each grade and several categories of use between 2001 and 2002.
• Lifetime use - 8th grade - 36.6 percent to 31.4 percent; 10th grade - 52.8 percent to 47.4 percent; 12th grade - 61.0 percent to 57.2 percent.
• Past month use - 8th grade - 12.2 percent to 10.7 percent; 10th grade - 21.3 percent to 17.7 percent; 12th grade - 29.5 percent to 26.7 percent.
• Daily use in past month - 10th grade - 12.2 percent to 10.1 percent; 12th - 19.0 percent to 16.9 percent.
• This follows several years of gradual decreases in cigarette smoking that started around 1996 for 8th graders and 1997 for 10th and 12th graders. However, year-to -year declines have not always been statistically significant in all grades, and the decreases seen between 2001 and 2002 are particularly notable.
• Use of bidis in the past year declined among 10th graders from 4.9 percent in 2001 to 3.1 percent in 2002. Use of these small, flavored cigarettes from India was reported by 2.7 percent of 8th graders and 5.9 percent of 12th graders in 2002 based on the past-year reporting period. Use of Kreteks (clove-flavored cigarettes from Indonesia) in the past year was reported by 2.6 percent of 8th graders; 4.9 percent of 10th graders, and 8.4 percent of 12th graders in 2002.
• Lifetime use of smokeless tobacco by 10th graders declined from 19.5 percent in 2001 to 16.9 percent in 2002.

• Between 2001 and 2002 significant reductions in alcohol use were observed among 8th and 10th graders in numerous categories of use, including lifetime, past year, and past month. The use rates in 8th and 10th graders are record lows in the history of the survey in those grades.
• Rates of having been drunk in the lifetime and past year decreased for 8th and 10th graders. Among 10th graders, the rate of binge drinking (five or more drinks in a row) in the past two weeks declined, as did the past-month rate of having been drunk.
• Perceived Harmfulness, Disapproval, and Perceived Availability
• Both perceived risk and disapproval of trying marijuana once or twice increased among 10th graders, but among 12th graders perceived risk of smoking marijuana regularly declined.
• Attitudes toward MDMA (Ecstasy) use hardened. Perceived risk of occasional MDMA use increased among 8th graders and perceived risk of trying it once or twice increased among 10th and 12th graders. Disapproval of MDMA use from 2001 to 2002 increased significantly among students in all three grades.
• Perceived risk and disapproval of trying LSD once or twice both increased among 12th graders, but among 10th graders perceived risk of regular LSD use decreased. Notably, perceived availability of LSD declined among students in all three grades.
• Perceived risk of trying inhalants once or twice declined among 8th graders, and perceived risk of regular use of these substances decreased among 10th graders. Seniors are not asked about their attitudes regarding inhalant use.
• Perceived availability of amphetamines decreased among 8th graders.

Psychiatric Disorders and Substance Abuse Disorders Among Youth in Juvenile Detention

Data are from a large (1829 youth, ages 10-18), random sample of male and female, white, African-American and Hispanic juvenile detainees in Cook County, IL. Among teens in juvenile detention, nearly two thirds of boys and nearly three quarters of girls have at least one psychiatric disorder. These rates dwarf the estimated 15 percent of youth in the general population thought to have psychiatric illness. Even when conduct disorder (common in this population) was excluded, nearly 60 percent of males and more than two-thirds of females met diagnostic criteria for, and also were functionally impaired by, one or more mental or substance use disorder. Half of males and almost half of females had a substance use disorder. Overall, disorders were more prevalent among older youth and females, more than 20 percent of whom had a major depressive disorder. Among boys, non-Hispanic whites had the highest prevalence for most disorders and African Americans the lowest. The exception was separation anxiety disorder, which was more prevalent among African Americans and Hispanics than among whites. Hispanics had higher prevalence than African Americans for panic disorder, obsessive-compulsive disorder and substance use other than alcohol or marijuana disorders. The only categories for which boys had higher prevalence than girls were manic episode, psychotic disorders, any substance abuse disorder, and marijuana use disorder. Longitudinal data are currently being collected on these youth. Teplin, L.A., Abram, K.M., McClleland, G.M., Dulcan, M.K., and Mericle, A.A. Psychiatric Disorders in Youth in Juvenile Detention. Arch. Gen. Psychiatry, 59, pp. 1133-1143, 2002.

Prevalence and Age of Onset for Drug Use in Seven International Sites

Kessler and colleagues present results of analyses of patterns of substance use utilizing data from seven population-based surveys carried out in six countries including the U.S., Canada, Brazil, Mexico, Germany and the Netherlands. All surveys utilized the Composite International Diagnostic Instrument (CIDI) to ascertain drug use. This study compares lifetime prevalence and age of first use for alcohol, cannabis, and other drugs. Alcohol and cannabis are the most widely consumed substances across all sites. Use of cannabis five or more times in a lifetime ranged from 28.8% in the U.S. to 1.7% in Mexico. While prevalence of use of different drugs varied widely from site to site, age of first use was similar across study sites. The authors suggest that this reflects a potentially strong linkage to stages of adolescent development and the influence of social role transitions in early adulthood. Comparisons of data from Mexico City, U.S., and Fresno, California (sample of Mexican-origin respondents including immigrants and U.S. born) revealed that lifetime drug use rates in the Fresno sample are lower than the national U.S. rates, but higher than those for the Mexico City population. The authors conclude that these findings suggest that drug use patterns may change among emigrating populations from low consumption nations as a consequence of international resettlement in nations with higher rates. Vega, W., Aguilar-Gaxiola, S., Andrade, L., Bijl, R., Borges, G., Caraveo-Anduaga, J., DeWit, D., Heeringa, S., Kessler, R.C., Kolody, B., Merikangas, K., Molnar, B., Walters, E., Warner, L., and Wittchen, H. Prevalence and Age of Onset for Drug Use in Seven International Sites: Results from the International Consortium of Psychiatric Epidemiology. Drug and Alcohol Dependence, 68, pp. 285-297, 2002.

Prevalence and Development of Psychiatric and Substance Use Disorders in Childhood and Adolescence

The authors used longitudinal data from a representative community sample of 1420 nine through sixteen year olds, to describe the prevalence and continuity of psychiatric disorders over time. Several significant findings were reported. By age 16, over a third (36.7%) of subjects met DSM-IV criteria for one or more disorders, and those with one disorder were 3 times more likely to have the same or another diagnosis at later waves. Rates of comorbidity were high, with one quarter (25.5%) diagnosed with 2 or more disorders at one time. Almost all disorders showed significant rates of continuity over time. Continuity from one diagnosis to another was significant between anxiety and depressive disorders, and from anxiety and conduct disorder to substance abuse, in girls. Substance use disorders increased with age and were more prevalent in boys than girls. The sample, while representative, does not represent the American population, but prevalence rates were comparable to those in several other studies. The notable points from this study relate particularly to the findings regarding continuity: that in a representative sample, only anxiety and conduct disorders predicted substance use disorders, and only in girls. This has important implications for improving our understanding of the etiology of adolescent drug abuse, for identifying those children at particular risk, and for developing and testing effective childhood interventions to prevent later drug abuse. Costello, E.J., Mustillo, S., Erkanli, A., Keeler, G., and Angold, A. Prevalence and Development of Psychiatric Disorders in Childhood and Adolescence. Arch Gen Psychiatry, 60, pp. 837-844, 2003.

Diminished Cortisol Response Among Offspring of Drug-Dependent Fathers

This report examines the salivary cortisol responses in preadolescent sons and daughters of fathers with and without drug-dependence, and the relative role of family environment. The high-risk boys and girls, relative to offspring of controls, demonstrated a diminished cortisol response in anticipation of a moderate stressor. Girls had significantly higher salivary cortisol concentrations, pre- and post-stressor. No association was found between salivary cortisol responses and measures of the family environment, however. These results suggest that there may be a sex difference in salivary cortisol dynamics in at-risk preadolescent children that is unrelated to current family environment. Hardie, T.L., Moss, H.B., Vanyukov, M.M., Yao, J.K., and Kirillovac, G.P. Psychiatry Research, 112(2), pp. 121-131, 2002.

Early Adolescent Marijuana Use: Risks for the Transition to Young Adulthood

This study assessed the relationship of early adolescent marijuana use to performance of developmental tasks integral to the transition to young adulthood. The tasks concerned intimacy, education, and work and social conformity. African American (N=617) and Puerto Rican (N=531) youths completed questionnaires in their classrooms. Five years later they were individually interviewed. Logistic regression analysis estimated the increased likelihood that early marijuana users would make an inadequate transition to young adult social roles. Analyses examining the association between early marijuana use and twenty outcome variables found significant relationships for ten of them: (a) having lower educational and occupational expectations; (b) being suspended or expelled from school, fired from jobs, 'high' at school or work, collecting welfare; and (c) rebelliousness, not participating in productive activities, not attending church, and being an unmarried parent. Marijuana use was not related to any of the intimate relationship measures. These finding emerged with controls on gender, ethnicity, age, and mother's education. Among African Americans and Puerto Ricans, early marijuana use predicts less adequate performance on some developmental tasks integral to becoming an independent young adult. Marijuana is not a benign drug and is associated with future risks for the individual and society at large. Brook, J.S., Adams, R.E., Balka, E.B. and Johnson, E. Early Adolescent Marijuana Use: Risks for the Transition to Young Adulthood. Psychological Medicine, 32, pp. 79-91, 2002

Marijuana Use Among the Adolescent Children of High-Risk Drug-Abusing Fathers

This study examines marijuana use among children of male drug abusers. Subjects were 83 African-American and European-American male drug abusers (the majority of whom were injection drug users) and their children. Thirty-one of the fathers were HIV-positive and 52 were HIV-negative. Using logistic regression analyses, we explored cross-sectionally the relationship between four psychosocial domains (i.e., paternal attributes, adolescent problem behaviors, father-adolescent relations, and the environment) and adolescent marijuana use. The father's use of illegal drugs and his failure to cope adaptively predicted adolescent marijuana use, while a close father-child bond were associated with less adolescent marijuana use. Adolescent problem behaviors were associated with an increased likelihood of marijuana use. Furthermore, hierarchical regression analysis demonstrated that the adolescent's problem behavior mediated the associations between the father-adolescent relationship as well as environmental factors with adolescent marijuana use. Reducing the risk factors and enhancing the protective factors within each of the domains could help reduce marijuana use among the adolescent children of drug-abusing fathers. Moreover, if a father is a drug abuser, it is important to help him establish a close bond with his child in order to help attenuate the influence of his drug use on the child's marijuana use. Brook, D.W., Brook, J.S., Richter, L., Whiteman, M. and Arencibia-Mireles, O. Marijuana Use Among the Adolescent Children of High-Risk Drug-Abusing Fathers. The American Journal on Addictions, 11, pp. 95-110, 2002.

The Longitudinal Relationship Between Drug Use and Risky Sexual Behaviors Among Colombian Adolescents

Community samples representing differing levels of risky sexual behavior and drug use were use to identify the longitudinal relationships between drug use, and risky sexual behaviors and early pregnancy in Colombian adolescents . Cohorts were drawn from higher and lower risk geographic areas as well as from various self-reported ethnic groups. Using regression analyses, controlling for demographic variables, a reciprocal, longitudinal relationship between risky sexual behaviors and drug use was identified. Those adolescents who reported higher levels of drug use at T1 also had more sexual partners and higher frequencies of unprotected sex, and they were also more likely to have experienced early pregnancy at T2. The reverse relationship was true as well. The level of violence experienced by the adolescent emerged as a moderator of some of these relationships. The results suggest that reducing adolescent drug use may also reduce levels of risky sexual behavior and early pregnancy and vice versa. Further, the importance of addressing violence as a risk factor for both problem behaviors is emphasized. Brook, D.W., Brook, J.S., Pahl, T. and Montoya, I., The Longitudinal Relationship Between Drug Use and Risky Sexual Behaviors Among Colombian Adolescents, Archives of Pediatric and Adolescent Medicine, 156, pp. 1101-1107, 2002.

Prevalence of Cigarette Smoking Among Rural Adolescents in the U.S.

Results are reported from a nationwide, U.S. study of cigarette smoking carried out from 1996 to 2000 involving 68,270 adolescents in grades 7 through 12 attending high school or the associated feeder junior high/middle school in a particular community. The sampling design was constructed to include students from a representative sample of rural communities in the United States. Based on responses to cigarette use survey items, students were classified into one of eight user categories, ranging from being a non-user to being a heavy user (i.e., ongoing use of a half a pack or more per day). Hierarchical linear modeling was used to model smoking as a function of grade, gender, region, and community size (rurality). Significant effects were found for rurality, region, grade, and gender. The highest levels of smoking were found for rural adolescents and adolescents living in the South. Males smoked more than females in all regions except the West, where females smoked more. Given that rural adolescents smoke more "heavily" than do their nonrural peers, researchers should devote more attention to understanding the factors that underlie smoking initiation in rural youth. Aloise-Young, P.A., Wayman, J.C., and Edwards, R.W. Substance Use and Misuse, 37(5-7), pp. 613-630, 2002.