Health and Developmental Consequences 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 developmental implications of drug use. 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.

Tolerance to the Disruptive Effects of Marijuana on Learning in Rats

Considering the widespread use of marijuana by school age adolescents and young adults, determination of marijuana's acute and chronic effects on learning is critically important. Chronic administration of marijuana is known to produce both tolerance and dependence (i.e., a withdrawal syndrome). The present study investigated the effects of tolerance and dependence following chronic administration of delta-9-THC (THC), the psychoactive ingredient in marijuana, on learning and performance in rats. Animals were trained on a complex discrimination to make sequences of three responses for food reinforcement. The discrimination was arranged such that drug effects could be evaluated separately on the learning (i.e., acquiring a new response sequence) and on the performance (i.e., executing a learned sequence) components of the task. The acute and chronic effects of THC were examined. To study the effects of dependence induced by repeated THC administration, learning and performance were also assessed after administration of a cannabinoid (CB1) receptor antagonist in chronically treated animals. Results indicated that a 5.6 mg/kg dose of THC disrupted learning and performance of the discrimination, but that tolerance developed to both the rate-decreasing and error-increasing effects of this dose during the learning and the performance components of the task. During chronic administration of THC, the CB1 antagonist, SR141716A, was occasionally given in place of THC. Whereas 1 mg/kg SR141716A alone is without effect on learning and performance measures in this paradigm, when substituted for THC in monkeys receiving a repeated regiment of THC injections, it selectively increased errors in learning but had little or no effect on performance. These data demonstrate that learning is more sensitive than performance to the disruptive effects of chronic dosing with THC, and suggest that this paradigm is useful for detecting subtle disruptions in cognitive function under conditions of withdrawal from THC. Delatte, M.S., Winsauer, P.J., and Moerschbaecher, J.M. Tolerance to the Disruptive Effects of delta-9-THC on Learning in Rats. Pharmacology, Biochemistry & Behavior, 74(1), pp. 129-140, 2002.

Prior Violence and Childhood Psychiatric History, But Not Substance Abuse, Predict Violence

The study examined whether scores on the Violence Proneness Scale, history of child and parent psychopathology, and substance abuse, could predict violence at age 19. At age 12-14, biological sons of fathers with and without substance use disorder completed a 13-item Violence Proneness Scale, which was derived by using items from the revised Drug Use Screening Inventory. The occurrence of violent acts was then assessed at a follow-up evaluation when the offspring were 19 years of age. A DSM-III-R axis I psychiatric disorder and a Violence Proneness Scale score of 10 or higher at age 12-14 predicted a violent outcome by age 19. The overall accuracy of prediction was 77%. Sensitivity was 81%, and specificity was 76%. Substance use disorder or psychopathology in the probands or substance use frequency in the children did not contribute to the prediction of violence. Tarter, R.E., Kirisci, L., Vanyukov, M., Cornelius, J., Pajer, K., Shoal, G.D., and Giancola, P.R. American Journal of Psychiatry, 159(9), pp. 1541-1547, 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

Drug Use and Neurobehavioral, Respiratory, and Cognitive Problems: Precursors and Mediators

To test a model of the early predictors and mediators of drug use and respiratory, neurobehavioral, and cognitive problems in adolescence and young adulthood. Authors prospectively examined self-reported measures of unconventional behavior, peer- and self-drug use and self-reported health problems in a sample of 286 males and 327 females. The sample represented the Northeastern United States at the time the data was first collected in 1975. The participants were assessed in early, middle, and late adolescence, and in young adulthood. Latent variable structural equation models were used to examine the data. Structural equation modeling conducted on the data provided support for the proposed longitudinal model. The findings indicated that adolescent drug use was associated indirectly with respiratory and directly with neurobehavioral and cognitive symptoms in young adulthood. Adolescent drug use during middle and late adolescence served as a mediator between unconventional behavior in early adolescence and health problems in young adulthood. A reduction in adolescent drug use may reduce respiratory and neurobehavioral and cognitive symptoms in young adulthood. This study identifies several points in the biopsychosocial pathways in adolescence leading to later health problems in young adulthood. Brook, J.S., Finch S.J., Whiteman, M. and Brook, D.W. Drug Use and Neurobehavioral, Respiratory, and Cognitive Problems: Precursors and Mediators. Journal of Adolescent Health, 30, pp. 433-441, 2002.

Adolescent Children of Alcoholics Experience Difficulty With the Leaving-Home Transition

The current study examined the extent to which various features of young adults' experiences of leaving home differed for children of alcoholic (COAs) versus nonalcoholic parents. A total of 227 young adults drawn from a high-risk, community sample of COAs and matched controls were interviewed at ages 18-23 years regarding their prior leaving home experiences. COAs showed greater difficulties in negotiating this transition, fewer positive feelings about the transition, and different reasons for leaving home as compared to participants without an alcoholic parent. Moreover, adolescent risk behaviors, family conflict, and family disorganization (assessed prior to this transition) each partly accounted for COAs' risk for difficulty in the leaving home transition. Hussong, A.M. and Chassin, L. Developmental Psychopathology, 14(1), pp. 139-157, 2002.