Genes, family environment, and gene-family environment interactions as predictors of adolescent alcohol use

Alcohol use among adolescents presents a large risk factor because it is
related to problem drinking and alcoholism later in life. Furthermore, recent
studies have revealed an alarming trend in alcohol use among Dutch adolescents.
It is therefore absolutely necessary to describe the determinants of adolescent
alcohol use. Research has shown that family influences can be important
predictors for alcohol consumption, while genetic research shows that
particular polymorphisms could play a role in different aspects of alcohol
use. The problem of current research is that it has had a too narrow focus
because it either examined environmental factors or genetic factors, although
it has been widely acknowledged by now that primarily the interaction between
environment and genes that is predictive of behavior. As fas as we know, the
project will be the first in the Netherlands that focuses explicitly on the
interaction between family environment and certain polymorphisms in predicting
various aspects of adolescent alcohol use (experimenting, regular drinking,
drunkenness, problem drinking).

Six research questions will be answered: 1) are the polymorfisms that we
examine differentially related to different aspects of alcohol use; 2) can
general parenting and alcohol-specific parenting predict different trajectories
of adolescent alcohol use; 3) to what extent does adolescent alcohol use
predict parenting; 4) how do particular polymorfisms interact with general
parenting in predicting adolescent alcohol use; 5) how do particular
polymorfisms interact with alcohol-specific parenting in predicting adolescent
alcohol use; 6) to what extent do particular polymorfisms interact with
differential parental treatment in predicting adolescent alcohol use.

The aim of the study is to describe to what extent the interaction between
family environment and specific polymorphisms can predict various aspects of
alcohol use (experimenting, regular drinking, problem drinking, drunkenness)
among adolescents aged 13 to 20.

The project is a continuation of ongoing project that included three
measurement waves (2002/2003, 2003/2004, en 2004/2005), with a period of one
year in between. During each wave, all four family members filled out
questionnaires.
In the present project, all families will be asked to participate in three new
data assessment waves, which will take place in 2006, 2007, and 2008.
Participation means that each participant wills out a questionnaire during each
wave. In addition, from each participant a small sample of genetic material
(saliva) will be collected in small oragenetic jars. To obtain the genetic
material it is sufficient when participants donate a small amount of saliva in
the jar, which is non-invasive. This genetic material will be analyzed in order
to find out whether it contains particular polymorphisms. In the protocol (NWO
grant application form) we have focused on the dopamine DRD2 gene, but in the
project other polymorphisms will be examined as well. The final selection of
polymorphisms (5 to 10 in total) that will be analyzed will be based on the
polymorphisms that have been identified in scientific studies at that time

Including the three new assessment waves we will have a unique data set on 400
families who have been assessed six times over a period of 5 years. Such a data
set is necessary in order to describe the development of alcohol use and its
various aspects (experimentation, regular drinking, drunkenness, problem
drinking).

As described under point E9a, there will be no risk attached to participating
to this study, and the burden will be very small. The reason is that the
participants will not undergo any invasive treatment, and will be only asked to
fill out one questionnaire during each assessment wave, and to donate a small
sample of saliva into a small jar by spitting into it.