Drinking Status but not Acute Alcohol Consumption Influences Impulsive Decision Making

1. Figure 1 Introduction Several studies have shown that heavier drinkers value smaller immediate monetary rewards over larger delayed rewards compared with lighter drinkers. However, findings on alcohol’s acute effects on delayed discounting are inconsistent. Delay discounting may vary with the type of reward offered. The aim of the present study was therefore to investigate: 1) the effects of alcohol on delay discounting, 2) the effects of drinking status on delayed discounting, and 3) whether these effects differ according to reward type. Methods Heavy and light drinkers (n = 96) were examined in a double-blind placebo-controlled design. Participants received an acute dose of alcohol at 0.40 g/kg or 0.60 g/kg or placebo in a between-subjects design. Delay discounting of alcohol and monetary rewards was measured using hyperbolic and Area Under the Curve (AUC) models of delay discounting. For the hyperbolic model higher discount scores indicate greater delay discounting (reverse for the AUC model). Results A mixed-model ANOVA of transformed hyperbolic discount scores indicated a main effect of reward type (F [1, 90] = 23.63, p < 0.001, η2 = 0.208), where all participants had higher discount scores for alcohol rewards compared with money rewards (Figure 1). A further main effect of drinking status was significant (F [1, 90] = 3.83, p = 0.031, η2 = 0.051), where heavier drinkers had higher discount scores compared with lighter drinkers (Figure 2). Transformed AUC discount scores also indicated a main effect of reward type was significant (F [1, 90] = 16.13, p < 0.001, η2 = 0.152), where all participants had lower discount scores for alcohol rewards compared with money rewards (Figure 3). Drinking Status but not Acute Alcohol Consumption Influences Impulsive Decision Making Figure 2 Sally Adams and Marcus R Munafò University of Bristol, School of Experimental Psychology Figure 3 Values are mean ± SE. Values refer to raw data. Discussion Our data indicate that all drinkers in the range examined, showed greater impulsive decision making towards alcohol rewards. Additionally, we observed that heavier drinkers discount the value of all delayed rewards more steeply than lighter drinkers. These findings suggest that impulsive decision making is influenced by individual differences in alcohol use, that is irrespective of state changes in alcohol intoxication. Sally Adams Department of Experimental Psychology, University of Bristol, 12a Priory Road, Bristol BS8 1TU, UK. sally.adams@bristol.ac.uk This poster is funded by an educational grant from University of Bristol