title: Trends in adolescent alcohol use: effects of age, sex and cohort on prevalence and heritability.
abstract: OBJECTIVE
  To determine the effect of age, sex and cohort on the prevalence and genetic architecture of adolescent alcohol use (AAU).
  
  
  METHODS
  Survey study in participants registered with the Netherlands Twin Register.
  
  
  METHODS
  Twins from the general population.
  
  
  METHODS
  Two cohorts (data collected in 1993 and 2005-08) of twins aged 13-15, 16-17 and 18-21 years. In 1993 and 2005-08 a total of 3269 and 8207 twins, respectively, took part.
  
  
  METHODS
  Survey data on initiation and frequency of alcohol use and quantity of alcohol consumed.
  
  
  RESULTS
  The prevalence of alcohol initiation increased between 1993 and 2005-08 for both males and females. The largest difference was for girls observed at ages 13-15, where the prevalence increased from 59.5% to 72.4%. We also found increases in prevalence across cohorts for quantity of alcohol consumed and non-significant increases for frequency of alcohol use. From age 16 onwards, boys drank more frequently and larger quantities than girls. Genetic model fitting revealed that the genetic architecture of AAU did not differ between birth cohorts, nor were there differences between boys and girls. Genetic factors explained between 21% and 55% of individual differences in alcohol measures throughout adolescence. Shared environment explained between 17% and 64% of variance in alcohol use, across different age groups and alcohol measures.
  
  
  CONCLUSIONS
  In the Netherlands, the prevalence of alcohol initiation, frequency and quantity has increased in adolescents over a 15-year period, but there are no changes in the genetic architecture of adolescent alcohol use.
authors.affiliation: Department of Biological Psychology, VU University, Amsterdam, The Netherlands. L.M.Geels@vu.nl
authors.forename: Lot M
authors.initials: LM
authors.lastname: Geels
authors.forename: Meike
authors.initials: M
authors.lastname: Bartels
authors.forename: Toos C E M
authors.initials: TC
authors.lastname: van Beijsterveldt
authors.forename: Gonneke
authors.initials: G
authors.lastname: Willemsen
authors.forename: Niels
authors.initials: N
authors.lastname: van der Aa
authors.forename: Dorret I
authors.initials: DI
authors.lastname: Boomsma
authors.forename: Jacqueline M
authors.initials: JM
authors.lastname: Vink
mesh_terms: D000293:Adolescent; D017677:Age Distribution; D000428:Alcohol Drinking / Q000453:epidemiology* / Q000235:genetics; D005260:Female; D006801:Humans; D008297:Male; D009426:Netherlands / Q000453:epidemiology; D015995:Prevalence; D018401:Sample Size; D017678:Sex Distribution; D014429:Twins, Dizygotic / Q000706:statistics & numerical data; D014430:Twins, Monozygotic / Q000706:statistics & numerical data; D055815:Young Adult