A human alcohol self-administration paradigm to model individual differences in impaired control over alcohol use

Abstract

We developed an alcohol self-administration paradigm to model individual differences in impaired control. The paradigm includes moderate drinking guidelines meant to model limits on alcohol consumption, which are typically exceeded by people with impaired control. Possible payment reductions provided a disincentive for excessive drinking. Alcohol use above the guideline, despite possible pay reductions, was considered to be indicative of impaired control. Heavy-drinking 21- to 25-year-olds (n = 39) were randomized to an experimental condition including the elements of the impaired control paradigm or to a free-drinking condition without these elements. Alcohol self-administration was compared between these two conditions to establish the internal validity of the experimental paradigm. In both conditions, participants self-administered beer and nonalcoholic beverages for 3 hours in a bar setting with 1-3 other participants. Experimental condition participants self-administered significantly fewer beers and drank to lower blood-alcohol concentrations (BACs) on average than those in the free-drinking condition. Experimental condition participants were more likely than free-drinking condition participants to intersperse nonalcoholic beverages with beer and to drink at a slower pace. Although experimental condition participants drank more moderately than those in the free-drinking condition overall, their range of drinking was considerable (BAC range = .024-.097), with several participants drinking excessively. A lower initial subjective response to alcohol and earlier age of alcohol use onset were associated with greater alcohol self-administration in the experimental condition. Given the variability in response, the impaired control laboratory paradigm may have utility for preliminary tests of novel interventions in future studies and for identifying individual differences in problem-drinking risk.

Figure 1

Timeline of participation on the day of an alcohol-self-administration session. BrAC, breath alcohol concentration; eBAC, estimated blood alcohol concentration during the ad-libitum-drinking period; RA, research assistant; “tasks,” the battery of 4 cognitive/psychomotor tasks administered initially at the in-person screening appointment

Figure 2.1

Number of beers self-administered during a 3-hour ad-libitum-drinking period in the experimental and free-drinking conditions. ** p<.01

Figure 2.2

Blood alcohol concentration-related outcomes. On the left, peak estimated blood alcohol concentration (eBAC) during a 3-hour ad-libitum-drinking period in the experimental and free-drinking conditions. On the right, peak actual breath alcohol concentration (BrAC) obtained after the end of the ad-libitum-drinking period in the experimental and free-drinking conditions. ** p<.01

Figure 3.1

Percentage of participants in each condition who self-administered at least 1 non-alcoholic beverage during a 3-hour ad-libitum-drinking period. ** p<.01

Figure 3.2

Depicts, from left to right, the mean duration taken to consume up to the first three beers during a 3-hour ad-libitum-drinking period by study condition; the mean interval between the end of the first and the beginning of the second beer by condition; and the mean interval between the end of the second and the beginning of the third beer by condition, * p<.05