The impact of gene-environment interaction on alcohol use disorders

Abstract

This article describes three types of gene-environment interactions and the challenges inherent in interpreting these interactions. It also reports on what is known about gene-environment interactions in the field of alcohol use disorders (AUDs). Twin studies of the interaction of genetic and environmental influences on AUDs have resulted in relatively consistent findings and have suggested general mechanisms for interaction effects. These studies generally find that environments that exert more social control (e.g., higher parental monitoring, less migratory neighborhoods, etc.) tend to reduce genetic influences, whereas other environments allow greater opportunity to express genetic predispositions, such as those characterized by more deviant peers and greater alcohol availability. Conversely, the gene-environment literature that has been developed surrounding specific genes has focused largely on the role of stress as a moderator of genetic effects.

Figure

A–C) The effect of genes and environment are used to predict the mean level of a quantitative trait Y. The lines depict five different genotypes with varying levels of liability to trait Y (e.g., symptoms of alcohol dependence). The environmental level of risk is depicted on the X-axis and ranges from level 1 (very low risk) to 5 (very high risk). A) An additive model of genetic and environmental effects. The key feature of this model is that the lines are all parallel—that is, the increase in the level of trait Y associated with a more adverse environment is the same for all genotypes. B) A fan-shaped interaction of genetic and environmental effects on trait Y. C) A cross-over interaction of genetic and environmental effects on trait Y.