Epidemiological and Psychosocial Perspectives on Adolescent Drug Use DENISE B. KANDEL, PH.D. Patterns of use of legal and illegal drugs among adolescents, with special emphasis on marijuana, are reviewed. Developmental patterns of drug involvement and a possible maturational trend in early adulthood are highlighted. Correlates, antecedents, and conse- quences of marijuana use are discussed. Despite dramatic increases in the use of marijuana in American society over the last decade, youths who use marijuana in 1980 show the same pattern of disaffection from major institutions as users in 1967. Many of the factors found to be associated with marijuana at one point in time precede rather than follow from its use. Illicit drugs appear to be used by some adolescents to handle feelings of distress. Journal of the American Academy of Child Psychiatry, 21,4:328-347, 1982. The epidemiological perspective provides insights into drug behavior that are not otherwise available from laboratory investigations or clinical studies. Es- pecially when the studies are based on large repre- samples of the general population, they pro- vide information on the distribution of the phenome- non in the population, on changes in patterns of use over time and among different groups, as well as on the natural history of involvement across the lifespan of individuals. By focusing on general populations rather than the most extreme and deviant groups included in clinical samples, epidemiological surveys provide normative data from which new understand- ings of drug behavior can be gained. For example, whereas alcoholics in treatment centers are generally in their mid-40s, surveys of men in the general popu- lation indicate that the most severe drinking-related problems occur in the early 20s (Cahalan and Room, 1974). Similarly, Robins' (1974) study of Vietnam vet- erans established that addiction was not necessarily a permanent state and that it was possible for young men to give up heroin without participating in any treatment program. Furthermore, longitudinal studies that follow the same individuals over time are ideally suited to eluci- date the possible causes and consequences of adoles- cent drug use. In such studies, a large number of young Dr. Kandel is Professor of Public Health in Psychiatry at Columbia University, and Head, Division of Youth and Family Studies, Department of Child Psychiatry, New York State Psychi- atric Institute. Reprints may be requested from Dr. Kandel at Department of Psychiatry, Columbia University, 722 W. 168th St., New York, NY 10032. Work on this review was partially supported by research grants DA 01097 Scope D and E, ROl DA 02867, and Research Scientist Award K05 DAOOO81 of the National Institute on Drug Abuse, and by the Center for Socio-Cultural Research on Drug Use, Columbia University. 0002-7138/82/2104-0328 $02.00/0 © 1982 by the American Acad- emy of Child Psychiatry. persons are followed over time so that one learns what distinguishes those adolescents who start using drugs from those who do not, and what happens to those youths who continue to use drugs. These longitudinal studies are among the most powerful since they have the potential of making it possible to disentangle causal factors from consequences in drug use, which are confounded in any research design in which data are gathered at a single point in time. Furthermore, such studies are the only means of identifying conse- quences of drug use that affect a person's ability to function as a productive member of society, such as performance in various social roles or delinquency, outcome variables that cannot be elicited in a labora- tory situation. This review examines epidemiological data on ado- lescent drug use with a special focus on marijuana. I address four questions: 1. How many young people are involved in drugs and in alcohol? What are the important patterns of drug use? 2. Who are the principal users of marijuana? 3. What is known about the antecedents of mari- juana use? 4. What are some of the consequences of marijuana use? Patterns of:Use Trends in Drug use The spread in the use of marijuana and other illicit drugs by young people represents one of the most striking phenomena of the last decade. Only in the last 3 years are there signs suggesting that marijuana use may be stabilizing (Johnston et al., 1981; U.s. Journal of Drug and Alcohol Dependence, 1981). Thus, the proportion of young adults 18 to 25 years of age who ever experimented with marijuana showed dramatic increases from 4% in 1962 to 68% in 1979. 328