Environmental and genetic influences on adolescent alcohol use: Insight into an etiological mechanism

Alcohol use among adolescents is omnipresent and can have deleterious short and
long term consequences. Family and twin studies have shown that a genetic
component is involved in alcohol use. Gene-phenotype association studies,
however, have not shown consistent results, possibly because environmental
factors are often not included. Examining gene-environment interactions is thus
very important if the aim is to gain more insight into the etiological risk
factors of alcohol use among adolescents.
The dopaminergic reward system in the brain plays an important role in the
rewarding effects of alcohol. Also the serotonergic system has received much
attention in the research for etiological factor in adolescent alcohol use.
With regard to environmental factors, former research at the Radboud University
has shown that adolescents consume less alcohol if their parents apply high
levels of alcohol-specific rules. A former study already showed that
adolescents carrying a mutation in a dopaminergic gene (the dopamine D2
receptor gene; DRD2) drank more alcohol if their parents were permissive
towards alcohol. The mechanism behind this effect is still largely unknown,
however. As impulsivity is related to the both dopaminergic and serotonergic
genes, but also to alcohol use, it could serve as an endophenotype in the
relationship between dopaminergic/serotonergic genotypes and alcohol use.

In this study the interaction between dopaminergic and serotonergic genes and
parental rule-setting on adolescent alcohol use and impulsivity will be
examined. The main aim is to gain more knowledge regarding the mechanism behind
the interaction effect between the dopaminergic/serotonergic genotypes and
parental rules on alcohol consumption among adolescents.

The present study consists out of two phases. In the first phase, approximately
350 adolescents will fill in a very short questionnaire. This will only take
approximately 5 minutes. In phase 2, based on the questionnaire data of phase
1, approximately a 100 adolescents will be selected and asked to participate in
the second phase of the study. The second phase exists of two school hours (a
double block or two separate school hours), in which questionnaires are filled
out, computer assignments are carried out, and saliva samples are collected for
DNA testing.

The present study does nog cause any risks and only a very small burden for the
participants. Participants are asked to fill out a couple of questionnaires and
carry out computer tasks in 2 school hours (1 double block or 2 separate school
hours). Also, participants are asked to fill an oragene pot with saliva. No
invasive operations are carried out.