genetic (a11), shared environmental (c11) and nonshared environmental (e11) influences. The second, more complex model (“Alcohol Exposure”) is similar to the first, simpler model in nearly all regards except that the six A, C, E components shared and unique to P300 amplitude were expressed as linear functions of AAU scores. As such, the genetic and environmental influences that shape P300 amplitude were allowed to change with (be moderated by) AAU scores. For example, the shared genetic component between the moderator alcohol use (M) and P300 amplitude was expressed in the linear form a21 + βXa21M, where a21 is the parameter for common genetic influence on the P300 amplitude, βXa21 is a regression coefficient estimated from the data, and M is the level of AAU (expressed as a z-score in this report).
