Path analysis of P300 amplitude of individuals from families at high and low risk for developing alcoholism

Background: A substantial amount of evidence exists suggesting that P300 amplitude in childhood is a risk marker for later development of alcohol dependence. There is evidence that P300 amplitude is heritable. The goal of the present study was to determine if patterns of transmission differed in families who were either at high or low risk for developing alcohol dependence. Methods: Auditory P300 was recorded from 536 individuals spanning three generations. The path analytic TAU model was used to investigate the familial transmission of P300 amplitude in the two independent samples of families. Results: Transmission of P300 in high-risk families most likely followed a polygenic model of inheritance with significant parent-to-offspring transmission. Parent-to-offspring transmission was significantly greater in high-risk than low-risk families. Total phenotypic variance due to transmissible factors was greater in low-risk families than in high-risk families, however. A somewhat unexpected finding was the substantial correlation between mates for P300 amplitude in both high- and low-risk families. Conclusions: P300 is transmissible in families. Differences exist in the pattern of transmission for P300 in families at high and low risk for alcoholism.