Health and Developmental Consequences of Youth Drug Abuse

Research Findings from September, 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.

Methylphenidate (Ritalin") and MDMA ("Ecstasy") Adolescent Exposure in Mice: Long-Lasting Consequences on Cocaine-induced Reward and Psychomotor Stimulation in Adulthood

The consequences of methylphenidate and MDMA abuse during adolescence on vulnerability to subsequent drug abuse and relapse in adulthood are unknown. To investigate this question, researchers administered methylphenidate, MDMA or saline to adolescent (26 day old) mice for 7 days. After one month (62 days old; when mice are considered 'adults'), the three groups of mice received cocaine injections for 4 or 5 days to determine their sensitivity to the rewarding and psychomotor stimulating effects of cocaine in adulthood. The rewarding effect of cocaine was determined in the conditioned place preference paradigm, and cocaine-induced psychomotor stimulation was determined by measuring locomotion. They found that cocaine induced the same magnitude of place preference in the control and MDMA groups, suggesting that exposure to MDMA did not alter the acquisition of the rewarding effect of cocaine. The methylphenidate group developed lower place preference, suggesting that exposure to methylphenidate diminished the acquisition of the rewarding effect of cocaine. In the locomotor activity studies, the methylphenidate group showed enhanced sensitivity to cocaine compared to the saline and MDMA groups. To investigate their response to challenge cocaine injection following cocaine withdrawal (a measure for drug relapse), mice remained drug free for 14 days and were re-tested in response to a low dose of cocaine. This low dose of cocaine induced very high place preference response as well as pronounced locomotor stimulation in the methylphenidate and MDMA pre-exposed groups, but not in the saline group. These findings demonstrate that (1) adolescent exposure to methylphenidate or MDMA ultimately elicits similar consequences in response to cocaine during adulthood and (2) the sensitized or heightened response to cocaine is expressed primarily after withdrawal from the initial exposure to cocaine. Thus, although the initial responses to cocaine of the drug pre-exposed mice were not always different from those of the saline pretreated mice, the methylphenidate and MDMA pre-exposed subjects ultimately developed significantly higher sensitivity to both the rewarding and psychomotor stimulating effects of cocaine after the withdrawal period from cocaine. The implications of these findings for human adolescent exposure to methylphenidate and MDMA should be cautiously regarded. However, these results suggest that although methylphenidate and MDMA pre-exposed subjects may not be more prone to initiate drug use, they may exhibit greater vulnerability than unexposed subjects to drug relapse after drug use has been initiated. Achat-Mendes, C., Anderson, K.L., and Itzhak, Y. Methylphenidate and MDMA Adolescent Exposure in Mice: Long-Lasting Consequences on Cocaine-induced Reward and Psychomotor Stimulation in Adulthood. Neuropharmacology, 45, pp. 106-115, 2003.

Ethnic Differences in Smoking Withdrawal Effects Among Adolescents

At the University of Memphis, smoking withdrawal effect information was collected from 75 adolescents making a quit attempt during a school-based smoking cessation program. A strong need to smoke was the most common withdrawal effect, followed by irritability and difficulty concentrating. Most participants experienced two or more withdrawal effects during the quit attempt, and withdrawal effects were evident in those smoking less than daily. Significant ethnic differences were found, with African Americans reporting significantly fewer withdrawal effects than Caucasians. After controlling for smoking frequency, African Americans were still less likely to report irritability, difficulty concentrating, and restlessness. Participants who chose to use nicotine replacement during the quit attempt were more likely to report difficulty concentrating, restlessness, and feeling miserable. Reidel, B.W., Robinson, L.A., Klesges, R.C. and McLain-Allen, G. Addictive Behaviors, 28(1), pp. 129-140, 2003.

Drug-Use Initiation and Conduct Disorder among Adolescents in Drug Treatment

This study investigated effects of drug-use initiation and conduct disorder (CD) among 1,031 adolescents who participated in the Drug Abuse Treatment Outcomes Studies for Adolescents (DATOS-A) sponsored by the National Institute on Drug Abuse (NIDA). The mean age of first drug use was 12.7 (S.D.=2.2), 57% met DSM-III-R criteria for CD, and earlier initiators were more likely to have CD. About 78% of the adolescents with CD reported that their first CD symptom occurred prior to drug-use initiation. The proportions of adolescents who had prior treatment were similar (about 28%) across all groups, but earlier initiators reported a greater number of treatment episodes and younger ages at their first treatment. Conduct disordered adolescents revealed greater problems prior to DATOS-A treatment, but they appeared to be more motivated and ready for treatment. Although adolescents with CD still showed worse outcomes after treatment, the impact of CD appeared to lessen when pretreatment differences were controlled. To a lesser extent, adolescents who began using drugs at earlier ages had greater alcohol and drug use and other problems at intake, but their treatment outcomes appeared to be similar to later initiators. There were few significant interaction effects of initiation and CD. Findings from this study highlight the importance of better understanding the progression of drug use, treatment utilization, and psychiatric comorbidity among adolescents with substance abuse problems. Hser, Y.I., Grella, C.E., Collins, C., and Teruya, C. Drug-Use Initiation and Conduct Disorder Among Adolescents in Drug Treatment. Journal of Adolescence, 26(3), pp. 331-345, 2003.

Self-Reported Health Status Among Treated Methamphetamine Users

Little research has examined how drug abuse is related to general health status over the long term among young and middle-aged adults. The authors investigated how self-reported health status is related to prolonged methamphetamine use in a diverse sample of 350 methamphetamine users, ages 18 to 52, who have been treated for drug abuse. Using retrospective data, the authors investigated how prolonged methamphetamine use in younger and older age groups is related to two self-reported measures of current health status: overall health, and presence of a health condition that began after starting illegal drug use. The authors controlled for the effects of drug use history, social and demographic factors, and other early experiences (e.g., early sexual abuse) that might pose obstacles to good health later in life. They found that having a current health condition is predicted by greater age and by more prolonged methamphetamine use, especially among younger adults. Early sexual abuse predicts both measures of poor health. Current health status is predicted by several measures of drug use history and early experiences, but by fewer social and demographic factors. The results suggest that reduction of methamphetamine use among younger people is important in promoting their later health and that methamphetamine treatment services could be improved by a greater understanding of how early experiences influence later health. Greenwell, L., and Brecht, M.L. Self-Reported Health Status Among Treated Methamphetamine Users. American Journal Of Drug And Alcohol Abuse, 29(1), pp. 75-104, 2003.