Smoking and intoxication after alcohol challenge in women and men: genetic influences

In an earlier analysis, men and women who were current or former smokers were found to report feeling less intoxicated on average than nonsmokers after ingestion of a challenge dose of alcohol. Here, we examine whether differences in subjective response to alcohol and a tendency to smoke cigarettes are transmitted together in families; and, if so, whether this association might be entirely explained by the same heritable factors that influence alcohol intake (as we might expect if both smoking and subjective intoxication are influenced by some general susceptibility for substance use). Alcohol challenge data on 388 Australian male and female twins (194 complete pairs) were reanalyzed using multivariate genetic analysis to evaluate the association between cigarette smoking and self-report intoxication after a standard dose of alcohol. In women, we could not reject the hypothesis of complete genetic overlap between effects on intoxication rating and history of smoking, and a significant residual genetic correlation between smoking and postalcohol intoxication persisted even when genetic influences on alcohol consumption were controlled for. In men, the familial association seemed to be largely environmentally mediated and associated with differences in drinking history. These findings prompt the question of whether, in some individuals, cigarette smoking may contribute to the development of tolerance to the effects of alcohol.