a1 Department of Mental Health and Substance Abuse Services, National Institute for Health and Welfare, Finland; Department of Public Health, University of Helsinki, Finland. firstname.lastname@example.org
a2 Department of Public Health, University of Helsinki, Finland.
a3 Virginia Institute for Psychiatric and Behavioral Genetics and Department of Psychiatry, Virginia Commonwealth University, United States.
a4 Department of Psychology, University of Jyväskylä, Finland.
a5 Department of Psychological and Brain Sciences, Indiana University, United States.
a6 Department of Mental Health and Substance Abuse Services, National Institute for Health and Welfare, Finland; Department of Public Health, University of Helsinki, Finland; Institute for Molecular Medicine, University of Helsinki, Finland.
a7 Department of Child and Adolescent Psychiatry, Erasmus Medical Center and Research Institute of Child Development and Education, University of Amsterdam, the Netherlands; IVO, Addiction Research Institute, Rotterdam, the Netherlands.
We examined whether externalizing problem behaviors (hyperactivity–impulsivity, aggressiveness, and inattention) predict illicit drug use independently, or whether their associations with drug use are mediated through cigarette smoking. We used a prospective longitudinal design within the FinnTwin12-17 study among Finnish adolescents with baseline at age 12 and follow-up surveys at ages 14 and 17. Path models were conducted with Mplus and included 1992 boys and 2123 girls. The outcome was self-reported ever use of cannabis or other illicit drugs at age 17. The predictors were: externalizing behaviors (hyperactivity–impulsivity, aggressiveness, and inattention) assessed by teachers and parents (age 12) and self-reported cigarette smoking (age 14). The findings differed across behavior studied. The association of hyperactivity–impulsivity with drug use was mostly mediated through earlier cigarette smoking. Concerning aggressiveness and inattention, the results were different among girls than boys. Among girls no significant mediation occurred, whereas among boys more consistent evidence on mediation was seen. Consistently in all models, the direct association of early cigarette smoking on drug use was strong and highly significant. We conclude that the associations of externalizing problem behaviors with illicit drug use are partially mediated through cigarette smoking. Although interventions targeting externalizing problem behaviors may protect adolescents from early onset smoking and subsequently experimenting with drugs, interventions to prevent cigarette smoking initiation are also important in reducing risk of later drug use.
(Received May 19 2010)
(Accepted August 26 2010)
c1 Address for correspondence: Tellervo Korhonen, University of Helsinki, Department of Public Health, P.O. Box 41, 00014 Helsinki, Finland.