(Portans et al., 1989) inferred acute tolerance to alcohol when subjects reported greater subjective effects on the ascending limb of the BrAC curve, compared to effects at a comparable BrAC on the descending limb. Alternatively, the magnitude of the effect at a particular blood alcohol concentration on the ascending limb is tracked until the effect is of the same magnitude on the descending limb, with differences in the blood alcohol concentration used as an index of acute adaptation to alcohol. In either approach, any brain sensitivity to the rate of change of alcohol exposure represents a confound that is compounded by the variability ensuing from use of the oral route of administration.
