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dc.contributor.advisorSlutske, Wendyeng
dc.contributor.authorRichmond-Rakerd, Leah S.eng
dc.date.issued2017eng
dc.date.submitted2017 Summereng
dc.description.abstract[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Behavioral genetic studies have provided insights into why early substance use initiation is associated with increased risk for disorder. Few genetically-informative studies, however, have operationalized initiation as the timing of first use and simultaneously modeled the timing of initiation and problematic use of multiple substances. Such research can help capture the risk associated with early initiation and determine the extent to which genetic and environmental risk generalizes across substances. This study utilized a behavior genetic approach to examine the relation between the age of substance use initiation and symptoms of substance use disorder. Participants were 7,285 monozygotic and dizygotic twins (40 percent male, mean age at interview equals 30.6) from the Australian Twin Registry who reported on their ages of tobacco, alcohol, and cannabis initiation and symptoms of DSM-IV nicotine dependence, alcohol use disorder, and cannabis use disorder. Biometric modeling was conducted to (a) determine the structure of genetic and environmental influences on initiation and disorder and (b) examine their genetic and environmental overlap. The latent structure of initiation differed across men and women. The familial covariance between initiation and disorder was genetic among men and genetic and environmental among women, suggesting that the relation between first substance use and disorder is partly explained by a shared liability. After accounting for familial overlap, significant unique environmental correlations were observed, indicating that the age of initiation of multiple drugs may directly increase risk for substance-related problems. Results support the utility of conceptualizing initiation in terms of age and of adopting a multivariate approach.eng
dc.identifier.urihttps://hdl.handle.net/10355/62277
dc.languageEnglisheng
dc.publisherUniversity of Missouri--Columbiaeng
dc.relation.ispartofcollectionUniversity of Missouri--Columbia. Graduate School. Theses and Dissertationseng
dc.rightsAccess is limited to the campuses of the University of Missouri.eng
dc.subject.FASTComorbidityeng
dc.subject.FASTSubstance abuse -- Age factorseng
dc.titleAge at first use and later substance involvement: characterizing genetic and environmental pathways for tobacco, alcohol, and cannabiseng
dc.typeThesiseng
thesis.degree.disciplinePsychology (MU)eng
thesis.degree.grantorUniversity of Missouri--Columbiaeng
thesis.degree.levelDoctoraleng
thesis.degree.namePh. D.eng


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