Background: Because the effects of susceptibility genes on alcohol use may differ as a function of age throughout adolescence and young adulthood, prospective study designs, in addition to cross-sectional ones are needed in genetic association studies. The short, low activity allele of a polymorphism (5-HTTLPR) in the serotonin transporter gene (SLC6A4) has been related to alcohol dependence. In the current study we tested whether 5-HTTLPR genotype was associated with adolescent alcohol use both cross-sectionally and longitudinally.
Methods: Non-regular drinkers (n=202) were selected from Dutch, nationwide sample of adolescents (mean age 13.4 at baseline) who were assessed across five annual waves. Latent growth curve modeling was applied to examine individual development of alcohol use over time, by estimating the initial level of alcohol use at Wave 2 (intercept), and the rate of change in alcohol use across time (slope).
Results: The 5-HTTLPR short allele predicted adolescent's growth (slope) in alcohol use over time. Adolescents with the 5-HTTLPR short allele showed larger increase in alcohol consumption than those without the 5-HTTLPR short allele. 5-HTTLPR genotype was not related to the initial level (intercept) of alcohol consumption. In all analyses we controlled for sex and personality.
Conclusions: To gain more insight into the etiological role of genetic determinants of adolescent alcohol use, developmental approaches that distinguish between onset and continuation of drinking should be applied.
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