In an important series of investigations, Schuckit and colleagues have shown that when compared with control participants, young adult males with family histories of alcoholism exhibit diminished reactions to a standardized dose of alcohol (i.e., a challenge test). Those reactions included the subjects’ subjective ratings of alcohol effects and their degree of body-sway compared with a baseline measurement taken before testing (e.g., Schuckit 1980, 1985). Although this work has been criticized on a number of methodological grounds (e.g., Newlin and Thompson 1990), Schuckit has completed a followup study showing that a low response to alcohol’s effects when originally tested predicts an increased risk of alcohol dependence at followup (Schuckit and Smith 1996). As we discuss below, these findings may provide one important clue as to how the association between smoking and alcohol dependence may arise. Schuckit has hypothesized that one subgroup of alcoholics may inherit a diminished reactivity to alcohol and because they experience less intoxication, less body-sway, or other similar effects after consuming a specified amount of alcohol, they are able to drink more heavily before becoming impaired and, thus, are more likely to progress to more harmful levels of alcohol use.
