title: The interactive effect of neighborhood peer cigarette use and 5HTTLPR genotype on individual cigarette use.
abstract: BACKGROUND
  Previous cross-sectional research has shown that adolescents' cigarette use is interactively associated with that of their school peers and their 5HTTLPR genotype, such that the cigarette use of persons with more copies of the 5HTTLPR*S' allele is more dependent on school peers' cigarette use behaviors than their counterparts. This analysis seeks to extend this novel finding by examining whether the same conclusion can be reached when substituting neighborhood peers for school peers and examining the timing of the initiation of any and regular smoking in adolescence.
  
  
  METHODS
  This analysis employs an independent sample with longitudinal measures of cigarette use among 6th through 8th graders clustered in 82 neighborhoods, of whom 1098 contributed genetic data. The proportion of respondents who had ever smoked cigarettes by the first wave was calculated for each census block group in the study. 5HTTLPR genotype was assayed using the method of Whisman et al. (2011). The timing of any or regular smoking initiation and over four years were modeled as dependent variables using Cox proportional hazard models.
  
  
  RESULTS
  The interaction of neighborhood peer smoking behavior in the first wave and 5HTTLPR genotype statistically significantly predicted any smoking initiation (hazard ratio: 3.532; p-value=0.002) and regular smoking initiation (hazard ratio: 5.686; p-value=0.000), net of controls for sex, race/ethnicity, grade in the first wave of data, and parental educational attainment. These findings reach the same conclusions as previous cross-sectional research.
  
  
  CONCLUSIONS
  These results differ in the model of gene-environment interaction that they support. The findings for any smoking initiation are consistent with the diathesis-stress model of gene-environment interaction; the findings for regular smoking initiation are consistent with the differential susceptibility model.
authors.affiliation: Department of Sociology, University of Alabama-Birmingham, United States. Electronic address: jddaw@uab.edu.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Daw
authors.affiliation: Department of Sociology, University of Colorado-Boulder, United States; Institute of Behavioral Science, University of Colorado-Boulder, United States; Institute for Behavioral Genetics, University of Colorado-Boulder, United States.
authors.forename: Jason D
authors.initials: JD
authors.lastname: Boardman
authors.affiliation: Department of Sociology, University of Colorado-Boulder, United States; Institute of Behavioral Science, University of Colorado-Boulder, United States.
authors.forename: Rachel
authors.initials: R
authors.lastname: Peterson
authors.affiliation: Institute for Behavioral Genetics, University of Colorado-Boulder, United States.
authors.forename: Andrew
authors.initials: A
authors.lastname: Smolen
authors.affiliation: Institute for Behavioral Genetics, University of Colorado-Boulder, United States.
authors.forename: Brett C
authors.initials: BC
authors.lastname: Haberstick
authors.affiliation: Institute for Behavioral Genetics, University of Colorado-Boulder, United States; Department of Integrative Physiology and Institute for Behavioral Genetics, University of Colorado-Boulder, United States.
authors.forename: Marissa A
authors.initials: MA
authors.lastname: Ehringer
authors.affiliation: Department of Health Behavior, Gillings School of Global Public Health, University of North Carolina-Chapel Hill, United States.
authors.forename: Susan T
authors.initials: ST
authors.lastname: Ennett
authors.affiliation: Department of Health Behavior, Gillings School of Global Public Health, University of North Carolina-Chapel Hill, United States.
authors.forename: Vangie A
authors.initials: VA
authors.lastname: Foshee
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior; D000328:Adult; D005260:Female; D059647:Gene-Environment Interaction; D005838:Genotype; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D010379:Peer Group; D012111:Residence Characteristics / Q000706:statistics & numerical data*; D050486:Serotonin Plasma Membrane Transport Proteins / Q000235:genetics*; D012907:Smoking / Q000453:epidemiology* / Q000235:genetics*; D015144:Southeastern United States / Q000453:epidemiology; D055815:Young Adult
chemical_list: C493230:SLC6A4 protein, human; D050486:Serotonin Plasma Membrane Transport Proteins
keywords: Adolescents; Cigarette smoking; Gene–environment interactions; Peer behavior; Peer effects