Conduct disorders in children at high risk for alcohol use disorders

Objective: To clarify the roles of genetic and environmental factors in the development of Conduct Disorder (CD) among offspring at high genetic and/or environmental risk for alcohol use disorders (AUDs). Method: Alcohol-related behaviors and psychiatric status were assessed in 1213 male twin members of the Vietnam Era Twin Registry (VETR), 1270 offspring, and 862 mothers of offspring. Through the use of an offspring-of-twins design, rates of CD were compared among four groups of offspring with varying genetic and environmental risk for AUDs. Results: Only offspring at both high genetic and high environmental risk for AUDs evidenced elevated rates of CD. Conclusions: Findings supported the common genes hypothesis, while maintaining that this genetic influence is conditional upon environmental factors that promote externalizing behaviors. Results are discussed in terms of Zucker’s “nesting hypothesis” (2002). BACKGROUND LITERATURE Studies of both genetic and environmental factors associated with CD provide evidence that the disorder occurs at higher rates among children of alcoholics (COAs). Family and social contexts associated with externalizing behaviors have been linked to alcohol use disorders (AUDs) later in life and CD is known to co-occur with alcohol abuse in adolescence ((Jacob & Johnson, 1997). The question remains, however, whether the source of this association is a genetic link between the disorders, an environmental factor present in alcoholic families that promotes externalizing behaviors in children, or a combination of the two (i.e. gene-environment interaction). The current study attempted, through the use of an offspring-of-twins design, to determine the relative contribution of genetic and environmental factors in the expression of CD in children at high risk for developing AUDs. Research questions were posed within the framework of a “latent externalizing factor model” (Krueger, Hicks, Patrick, Carlson, Iacone, & McGue, 2000), which posits that CD, adolescent antisocial behavior, Alcohol Dependence (AD), and illicit substance dependence are derived from a common genetic factor. It was hypothesized that environmental factors (i.e. being raised by an alcoholic parent) increase risk for the development of externalizing symptoms beyond the genetic risk posed from being the biological offspring of parents with AUDs.