Individual responsivity or “tolerance” to alcohol also is important and has been assessed by the BAC curve changes with consumption (Fillmore & Vogel-Sprott, 1998). The rising limb theory supposes that heavy drinkers are more sensitive than light drinkers to the subjective positive euphorigenic effects during the early portion of the BAC curve but less sensitive to the sedative-like effects during both the rising and declining phases (Holdstock, King, & de Wit, 2000). Young adult heavy binge drinkers (≥5/4 drinks on one occasion at least once a week) were found to produce this biphasic response on a battery of behavioral scales. An initial pattern of positive reinforcement and absence of negative effects was obtained for the binge compared with nonbinge drinkers (<5/4 drinks per occasion), who did not show a biphasic alcohol response and reported heightened sedation throughout both limbs of the BAC curve (King, Houle, de Wit, Holdstock, & Schuster, 2002). Although the biphasic response may have been produced by the binge pattern of consumption, the authors speculated that the differential sensitivity between binge and nonbinge drinkers may have contributed to the enhanced risk for the development of alcohol-use disorders and the acquisition of binge-drinking patterns.
