Epidemiology of Youth Drug Abuse

Research Findings from February, 2001 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.

Monitoring the Future (MTF) Study

Results from the MTF study were released on December 14, 2000. The major findings are summarized below. For more information, go to http://www.nida.nih.gov and to http://monitoringthefuture.org,, the MTF website at the University of Michigan.

Results from the 2000 Monitoring the Future (MTF) study indicate that use of marijuana and most other illicit drugs by 8th, 10th, and 12th grade students remained stable from 1999 to 2000, continuing their recent moderating trend. However, MDMA (ecstasy) use increased among students in each grade, and steroid use increased among 10th graders; this is the second year of increases for these drugs. Past year heroin use by seniors increased to its highest level since the survey began, based largely on an increase in noninjection use of the drug. On the positive side, hallucinogen use decreased among 10th and 12th graders, and cocaine use declined among 12th graders. Notably, use of cigarettes decreased in each grade. Alcohol use remained mostly unchanged. Attitudes toward substance use, which are often seen as harbingers of changes in use, showed little systematic change from 1999 to 2000. Exceptions to that included increases in disapproval of trying marijuana among 8th and 12th graders, declines in perceived risk of cocaine use among 10th graders, increases in perceived risk of cigarette use among 8th and 10th graders, and a decrease in perceived risk of steroid use among 12th graders. Unless otherwise noted, the changes discussed are statistically significant.

Illicit Drug Use

• For the second year in a row, lifetime, past year, past month, and daily use of marijuana/hashish remained unchanged from 1999 to 2000. The same held true for the any illicit drug use measure. Seniors' rate of lifetime marijuana use is at the lowest point since 1997.

• Use of MDMA (ecstasy) in the lifetime and past year increased among 8th and 12th graders, and current use of the drug increased among 8th and 10th graders. This continues a trend seen last year for the older students and extends it to the younger students in the study.

• Lifetime and past year steroid use by 10th graders increased, continuing an increase begun last year; steroid use among 8th and 12th graders remained stable.

• Among seniors, past year use of cocaine in any form decreased from 1999 to 2000. Lifetime use of crack and current use of other cocaine also declined for seniors.

• Hallucinogen use in general and use of LSD in particular declined among 10th and 12th graders, with current use down for both grades and past year use down among 12th graders.

• Heroin use showed mixed trends, with an increase in past year overall heroin use and use without a needle among 12th graders and a decline in past year use overall use and use with a needle in the lifetime and past year among 8th graders.

• Ever use of inhalants by 8th graders decreased in 1999 to its lowest level since 1993.

• Use of marijuana, PCP, narcotics other than heroin, methamphetamine, crystal methamphetamine ("ice"), barbiturates, tranquilizers, and Rohypnol remained stable for all three grades and for lifetime, past year, past month, and daily (where applicable) use.

Perceived Harmfulness, Disapproval, and Perceived Availability of Illicit Drugs

• Disapproval of trying marijuana once or twice increased among 8th and 12th graders.
• Perceived harmfulness of taking crack occasionally or taking cocaine powder once or twice or occasionally decreased among 10th graders.
• Perceived harm from steroid use decreased among seniors, the only class for whom measured.
• Disapproval of regular LSD use decreased among 8th graders.
• Perceived availability of MDMA and of hallucinogens other than LSD increased among seniors.
• Perceived availability of crack and cocaine powder decreased among 10th graders.

Alcohol Use

• Most measures of alcohol use remained unchanged from 1999 to 2000. The sole exception was a decrease in daily alcohol use among 8th graders.
• Perceived harm from trying one or two drinks of an alcoholic beverage decreased among 12th graders, and perceived availability of alcohol declined among 8th graders.

Use of Cigarettes and Smokeless Tobacco

• Use of cigarettes decreased notably in several categories from 1999 to 2000. Lifetime cigarette use declined among 8th and 10th graders; past month use decreased for 8th and 12th graders; and daily use in the past month and use of _ pack or more per day decreased among 10th and 12th graders.
• Perceived harm from cigarette use increased among 8th and 10th graders, and perceived availability of cigarettes declined among 8th and 10th graders (availability is not measured for seniors). Perceived harm from regular use of smokeless tobacco increased among 10th graders.

Community Epidemiology Work Group The 49th biannual meeting of the Community Epidemiology Work Group (CEWG) chaired by Mr. Nicholas J. Kozel, DESPR, was held in San Francisco, California, on December 12-15, 2000. The CEWG is composed of researchers from 21 metropolitan areas of the United States who meet semiannually to report on patterns and trends of drug abuse in their respective areas, emerging drugs of abuse, vulnerable populations and factors that may place people at risk of drug abuse, and negative health and social consequences. Reports are based on a variety of drug abuse indicator data, such as morbidity and mortality information, treatment data and local and State law enforcement data. Additional sources of information include criminal justice, correctional, medical and community health data, local and State survey information and findings from focus groups and qualitative research studies.

The following are highlights from the meetings:

Cocaine/Crack - Indicators continue to decline, a trend reported in 18 of the 21 CEWG areas. The downward trend is especially striking in areas where abuse of these drugs has been highly concentrated in the past, such as the Northeast, mid-Atlantic, and northern Midwest region of the Nation. There appears to be an aging factor among crack abusers. Nevertheless, cocaine/crack indicators remain elevated in most CEWG areas, and cocaine ranked first in DAWN ME drug-related deaths in nine CEWG sites. Indicator data show that cocaine is frequently used concurrently or sequentially with other substances.

Heroin - Indicators are trending upward in 15 CEWG sites located across the Nation. Heroin/morphine ranked first in DAWN ME drug-related mentions in eight CEWG areas. As in the past, CEWG members continued to report increases in heroin indicators among young populations. Data also show that heroin is often used in combination with cocaine (either concurrently or sequentially).

Marijuana - Indicators were mixed across CEWG areas, but there were signs that abuse of the drug is stabilizing in some areas after the dramatic upsurge from 1990-1998. While decreases or stabilization were characteristic of such indicators as ED mentions, almost all CEWG members reported increases in primary marijuana treatment admissions. Recent indicator data also show that marijuana is more likely than other illicit drugs to be used in combination with different substances, including hydrocodone and MDMA (methylenedioxymethamphetamine or ecstasy).

Methamphetamine - Indicators, which appeared to be trending downward from 1997 through the first half of 1999, showed signs of increasing again during the last half of 1999. Reports from 11 CEWG areas indicate that methamphetamine is being used along with other drugs at dance venues such as raves. There are signs also that methamphetamine is increasing in areas where it has not been a major problem in the past. A serious and sometimes fatal practice of using Viagra in combination with methamphetamine and other drugs is being reported by ethnographers.

MDMA (ecstasy) - is being closely monitored in CEWG areas. CEWG members from 17 areas report that ecstasy abuse has become more widespread recently. Members also report that ecstasy is now being used in a variety of settings, including raves, house parties and singles bars and age groups appear to be getting younger. DAWN ED mentions show that MDMA use in combination with marijuana/hashish increased from 8 in 1990 to 796 in 1999.

Emerging Drugs - Among emerging drugs of abuse are several licit substances: clonazepam (a benzodiazepine) and hydrocodone, hydromorphone, and oxycodone (controlled substances). Hydrocodone, e.g., Lorect, Lortab, appears to be the most widely abused. From 1993 to 1999, DAWN ED hydrocodone mentions increased 139 percent (from 6,115 to 14,639).

Links Between School Misbehavior, Academic Achievement, and Cigarette Use

The directionality of the association between substance abuse behaviors and negative school behaviors is unclear. In a study using the Monitoring the Future follow-up panel data, investigators at the University of Michigan examined relations among academic achievement, school bonding, school misbehavior, and cigarette use from 8th to 12th grade in two national panel samples of youth (n=3056). A series of competing conceptual models developed a priori was tested using structural equation modeling (SEM). The findings suggest that during middle adolescence the predominant direction of influence is from school experiences to cigarette use. School misbehavior and low academic achievement contribute to increased cigarette use over time both directly and indirectly. Two-group SEM analyses involving two cohorts -- gender and ethnicity -- showed robust findings. In addition, comparisons between high school dropouts and non-dropouts and between 8th grade cigarette use initiators and nonusers revealed few differences in direction or magnitude of effects. Results suggest that prevention programs that attempt to reduce school misbehavior and academic failure, as well as to help students who misbehave and have difficulty in school constructively avoid negative school- and health-related outcomes, are likely to be effective in reducing adolescent cigarette use. Bryant, A.L., Schulenberg, J., Bachman, J.G., O'Malley, P.M., and Johnston, L.D. Understanding the Links Among School Misbehavior, Academic Achievement, and Cigarette Use: A National Panel Study of Adolescents. Prevention Science, 1(2), pp 71-87, 2000.

Inhalant Use Among High School Students in Illinois

Researchers at the University of Illinois at Chicago analyzed data from two years (1993 and 1995) of a statewide survey of high school students on drug use. Changes in the rates of inhalant use, and associations between inhalant use and sociodemographic variables, were examined across the two survey years. Measures of inhalant use included lifetime use, past year use, and past month use. Analyses showed no significant difference in the rates of inhalant use across years. Associations with sex, ethnicity, and age were partly consistent with previous research findings. Both lifetime and recent inhalant use were more prevalent among males than females. Blacks were less likely to use inhalants (lifetime and recent) than other racial/ethnic groups in both survey years. Native Americans showed elevated rates of recent inhalant use in 1993 but not in 1995. While patterns in age-specific rates in the 1993 survey were consistent with expectations, those in the 1995 survey were not: recent inhalant use was constant across age groups in the 1995 sample. Also contrary to expectations, inhalant use was not more prevalent in low-income or high- poverty areas. The associations of inhalant use with family intactness and academic performance varied by race/ethnicity. Family intactness was a significant protective factor only for whites and Hispanics. Poor grades were not a significant predictor of lifetime inhalant use for blacks, and the protective effect of high grades was found only for whites. Poor grades were highly predictive of lifetime inhalant use for Asians. Mackesy-Amiti, M.E. and Fendrich, M. Trends in Inhalant Use Among High School Students in Illinois: 1993-1995. American Journal of Drug and Alcohol Abuse, 26(4), pp. 569-590, 2000.

Gender Differences in Validity of Drug Use Reporting by Juvenile Arrestees

In an exploratory study, investigators at the University of Illinois at Chicago looked at the validity of drug use reporting among arrestees. Past studies on this topic have not included enough females to study gender differences. This study examined gender differences in the validity of drug use reporting among juvenile arrestees, using a gender-matched sample (n = 6,377) drawn from the Drug Use Forecasting Program for 1992-1996. Self-reported marijuana and crack and/or cocaine use was compared to urinalysis results to test gender differences in the accuracy of disclosure. Among urine positives, girls were more willing than boys to disclose past month and lifetime marijuana use. Gender was not a significant main effect for cocaine use reporting but interacted with race/ethnicity and family structure in predicting valid disclosure. Hispanic girls were significantly more likely than Hispanic boys to under report recent cocaine use. Among arrestees from homes with one or no parents, girls were significantly more likely than boys to disclose recent cocaine use. Kim, J.Y., Fendrich, M., and Wislar, J.S. The Validity of Juvenile Arrestees' Drug Use Reporting: A Gender Comparison. Journal of Research in Crime and Delinquency, 37(4), pp. 419-432, 2000.

Decreased Drug Reporting in a Cross-Sectional Student Drug Use Survey

Longitudinal cohort studies have suggested that reinterviews about drug use often lead to decreased reports of lifetime substance use (recanting). Respondents may edit their answers on reinterview because of perceptions regarding question threat. Since reinterviews usually occur after long periods of time, the influence of inadequate recall (memory), cannot be ruled out. In order to evaluate the relative importance of editing and memory on recanting, researchers examined a cross-sectional survey administered in 1993 to a probability sample of Illinois students who were in the 7th through 12th grade. Two sets of self-administered survey questions assessed drug use in this survey: the I-SAY drug-use questionnaire, and a supplemental questionnaire asked at the end of the survey. Rates of "new use " (i.e., cases where use of a drug was not reported in the I-SAY questionnaire but was reported on the supplement) with rates of recanting (use for a drug reported on the I-SAY but no use for the drug reported on the supplement). Findings indicate that recanting was generally more pronounced than was new use, especially for cocaine, heroin, marijuana, and inhalants. Those classified as light or inconsistent users on the I-SAY were significantly more likely to recant their drug use reports. Fendrich, M. and Mackesy-Amiti, M.E. Decreased Drug Reporting in a Cross-sectional Student Drug Use Survey. Journal of Substance Abuse, 11(2), pp. 161-172, 2000.

Methamphetamine Use by High School Students

Researchers at the Tri-ethnic Center for Prevention Research at Colorado State University analyzed data on 9th through 12th graders' methamphetamine use reported in the American Drug and Alcohol Survey (n=629,722). From 1989 through 1992, methamphetamine use rates remained relatively stable. Since then, rates have increased, almost doubling, especially in Western states. There were no significant differences in methamphetamine use across year in school, but males were more likely to use than females though use among females has also increased. American Indians and Hispanics were more likely to use methamphetamine, followed (in order) by Asian Americans, White non-Hispanics, and African Americans. Compared to other heavily drug involved youth, methamphetamine users were more likely to use other drugs. The most commonly reported other drugs used by students who used methamphetamine were alcohol, marijuana, hallucinogens, uppers, and cocaine. Methamphetamine users were also more likely than other drug users to suffer drug use consequences such as traffic tickets, car accidents, being arrested, trouble at school, fighting, and other adverse consequences. Oetting, E.R., Deffenbacher, J.L., Taylor, M.J., Luther, N., Beauvais, F., and Edwards, R.W. Methamphetamine Use by High Schools Students: Recent Trends, Gender and Ethnicity Differences, and Use of Other Drugs. Journal of Child and Adolescent Substance Abuse, 10(1), pp. 33-50, 2000.

Nicotine Dependence Rates Vary by Gender, Ethnicity, and Age

This study used data from the National Household Survey on Drug Abuse to look at the relationship between numbers of cigarettes used and symptoms of nicotine dependence, for various groups. The authors found that rates of nicotine dependence were highest among females, whites, and adolescents and younger adults (below age 50); each of these groups experienced more dependence symptoms while using the same or fewer number of cigarettes. Dependence rates increase sharply up to half a pack of cigarettes smoked per day. This study is unusual in using epidemiologic data from a large study to begin examining population prevalence and differential rates of nicotine dependence symptoms. It suggests that different thresholds of quantity and duration of smoking should be used in assessing different groups for risk for nicotine dependence, and that the risk for developing dependence increases sharply at lower levels of smoking (up to half a pack per day). Of particular note is the finding that adolescents, women, and whites were particularly vulnerable to the development of dependence symptoms at lower levels of consumption than their counterparts. Kandel, D.B. and Chen, K. Extent of Smoking and Nicotine Dependence in the United States: 1991-1993. Nicotine and Tobacco Research, 2, pp. 263-274, 2000.

Heritability of Tobacco Consumption Varies by Gender and Time Cohort

This article reports the largest and most comprehensive analysis to date of twin data yielding heritability estimates for tobacco use. The probands were obtained from a Swedish registry of twins born since 1886. By comparing monozygotic (MZ) and dizygotic (DZ) twin pairs, heritabilities for males was 56% with considerably lower contributions to the variance for use of tobacco; 24% and 20% for familial-environment and individual-specific environment risk factors, respectively. The pattern for females was not the same and subsequent analyses were needed to understand the differences. What seemed to matter for females was the era of their birth: those born in the first and second third of the cohort had much less heritability than those born in the last third (since 1940). In fact, those females born most recently had essentially the same heritability as males. The authors' conclude that "a reduction in the social restrictions on smoking in women in Sweden as the twentieth century progressed permitted genetic factors influencing the risk for regular tobacco use to increasingly express themselves."

A second result from this study is noteworthy. Twin correlations for amount of tobacco consumed were significant in MZ twins but not DZ twins, supporting the hypothesis that substance use is a two stage process: initiation and continued use (or misuse). Finally, the large number of twins studied allowed comparison of both MZ and DZ twin pairs who were either reared together or reared apart. This is important to address what is known as the "equal environment assumption" that assumes MZ and DZ twins are correlated in their exposure to their environment. In analyses addressing this issue, it was found that that the equal environment assumption was sufficiently valid so as not to introduce particular environmental biases due to zygosity. Kendler, K.S., Thornton, L.M., and Pedersen, N.L. Tobacco Consumption in Swedish Twins Reared Apart and Reared Together. Archives of General Psychiatry, 57, pp. 886-892, 2000.

Ethnicity and Gender in Polydrug Use

The purpose of this study was to determine if ethnic and gender differences in polydrug use exist among a cohort of inner-city adolescents during the three-year middle school period. Students in 22 urban schools completed self-report questionnaires with measures of drug use (smoking, drinking, and marijuana use) at three annual assessments. For participating students, (N=2354), analyses of variance were conducted to test for ethnic group (Asian, Black, Hispanic, and White) and gender differences in polydrug use. Ethnic differences were found for polydrug use measures at each assessment point. Asian and Black adolescents generally reported less polydrug use than White and Hispanic youth. When gender differences were evident, boys engaged in more use than girls. The relatively high rates of polydrug use indicate that prevention intervention programs that target multiple substances may be more efficient in reducing overall risk than prevention programs that focus on a single substance (e.g., smoking prevention only). Epstein, J.A., Botvin, G.J., Griffin, K.W., and Diaz, T. Role of Ethnicity and Gender in Polydrug Use Among a Longitudinal Sample of Inner-City Adolescents. Journal of Alcohol and Drug Education, 45, pp. 1- 12, Fall 2000.

Risk Factors for Early Tobacco Experimentation

This prospective study examines the relations between the mother's prenatal and current smoking and the offspring's smoking experimentation. A low SES birth cohort of 589 10-year-olds, who have been followed since their gestation, completed a self-report questionnaire about their substance use. Half were female, and 52% were African-American. Detailed data on exposure to tobacco and other substances in the prenatal and postnatal periods were collected from the mothers. During pregnancy, 52.6% of the mothers were smokers; 59.7% were smokers when their children were 10. Six per cent of the children (37/589) reported ever-smoking cigarettes, 3% had had one full alcoholic drink, and none had started to use other drugs. Maternal smoking during pregnancy was significantly associated with an increased risk of the child's tobacco experimentation. Offspring exposed to more than _ pack per day during gestation had a 5.5-fold increased risk for early experimentation. Structural equation modeling showed that prenatal tobacco exposure had a direct and significant effect on the child's smoking and that maternal current smoking was not significant. Prenatal tobacco exposure also predicted child anxiety/depression and externalizing behaviors, and these outcomes affected child smoking through the mediating effect of peer tobacco use. Cornelius, M.D., Leech, S.L., Goldschmidt, L., and Day, N.L., Prenatal Tobacco Exposure: Is It A Risk Factor For Early Tobacco Experimentation? Nicotine & Tobacco Research, 2, 45-52, 2000.

Paper vs. Computer-assisted Self Interview for Alcohol, Tobacco, and Other Drug Surveys

School surveys of alcohol, tobacco, and other drug use (ATOD) play an important role in evaluating prevention programs and developing policy. Until recently, most surveys are conducted with paper and pencil (PAP) instruments, but computer-assisted self-interviews (CASI) methods are becoming more common. Evidence on CASI methods indicates that they elicit higher rates of positive responses to sensitive questions than traditional measures. This study examines whether ATOD school surveys using CASI are feasible and improve the quality of data. Seventh, ninth, and eleventh grade students in two California communities were randomly assigned to PAP or to CASI (n=2296). The findings indicate that while CASI did not increase reported rates of substance use over PAP it significantly improved the speed of data processing and decreased the incidence of missing data. CASI was well accepted by students and school staff despite problems such as lack of computer resources. Hallfors, D., Khatapoush, S., Kadushin, C., Watson, K., and Saxe, L. A Comparison of Paper vs. Computer-assisted Self Interview for School Alcohol, Tobacco, and Other Drug Surveys. Evaluation and Program Planning, 23, pp. 149-155, 2000.