Families of alcoholics have been reported to undergo heightened stress because of the increased family conflict and lesser family cohesion seen within the family system . Because chronic stress contributes to neuronal loss in regions of the limbic system , the study of childhood environment and its interaction with genetic variation may provide important clues concerning brain morphology and liability for alcohol dependence. We hypothesized that High-Risk offspring from multiplex alcohol dependence families might experience higher levels of family conflict and reduced family cohesion which might, in turn, result in smaller amygdala volume.
The present study obtained measures of family environment as part of a longitudinal study in which children/adolescents were evaluated annually and MRI imaging performed when the participants reached young adulthood. These data along with banked DNA made it possible to test the effects of the interaction of family environmental characteristics with candidate genes on amygdala volume. Because the candidate genes were chosen based on their effect on the neuronal growth and plasticity of amygdala networks  and their potential moderating effects on the impact of childhood adversity [16,35], the interaction between the genes and characteristics of the childhood family environment were tested for their effect on amygdala volume.