Genetic Modeling of Tobacco Use Behavior and Trajectories

Genetic studies have provided strong evidence that heritable factors generate individual differences in smoking behavior. Shared environmental factors appear to play a larger role in tobacco use at earlier ages. Improved modeling techniques hold the potential to better differentiate between genetic and environmental factors in tobacco use. This chapter examines genetic modeling issues in the study of smoking trajectories and behavior, including ■ Methodological and conceptual issues such as inferring potential dependence and trajectories in nonsmokers, issues in measurement invariance, and the use of epidemiological methods in genetically informative studies ■ Statistical modeling considerations such as the use of structural equation modeling (SEM) to assess whether covariation between traits is due to genetic or environmental causes, the identifi cation of genetic latent classes, and the analysis of molecular genetic data from linkage and association studies ■ A review of prior genetic studies of smoking behavior, including twin and extended twin family studies, multivariate genetic studies, and molecular genetic studies ■ A study applying an item response theory (IRT) approach to an analysis of smoking trajectories with data from the Virginia Twin Registry, examining tobacco initiation, regular tobacco use, and items on the modifi ed version of the Fagerström Tolerance Questionnaire (FTQ) The IRT study in this chapter underscores the importance of assessing measurement invariance in establishing the heritability of nicotine dependence and its variation with gender