A comparison of implicit and explicit reward learning in low risk alcohol users versus people who binge drink and people with alcohol dependence

Abstract

Chronic alcohol use leads to specific neurobiological alterations in the dopaminergic brain reward system, which probably are leading to a reward deficiency syndrome in alcohol dependence. The purpose of our study was to examine the effects of such hypothesized neurobiological alterations on the behavioral level, and more precisely on the implicit and explicit reward learning. Alcohol users were classified as dependent drinkers (using the DSM-IV criteria), binge drinkers (using criteria of the USA National Institute on Alcohol Abuse and Alcoholism) or low-risk drinkers (following recommendations of the Scientific board of trustees of the German Health Ministry). The final sample (n = 94) consisted of 36 low-risk alcohol users, 37 binge drinkers and 21 abstinent alcohol dependent patients. Participants were administered a probabilistic implicit reward learning task and an explicit reward- and punishment-based trial-and-error-learning task. Alcohol dependent patients showed a lower performance in implicit and explicit reward learning than low risk drinkers. Binge drinkers learned less than low-risk drinkers in the implicit learning task. The results support the assumption that binge drinking and alcohol dependence are related to a chronic reward deficit. Binge drinking accompanied by implicit reward learning deficits could increase the risk for the development of an alcohol dependence.

Keywords: Alcohol dependence; Binge drinking; Implicit and explicit reward learning; Low risk alcohol use.

Fig. 1

Plasticine puppet – the customer in the ice-cream parlor, created by the artist Thorsten Drössler – with four different cues and two possible outcomes (IST).

Fig. 2

a/b. Corrected means and standard errors of the mean frequencies of optimal responses in the IST for the three groups (black: Low-risk Drinker, Binge Drinker, Alcohol Dependent Patients). The light grey lines show means and standard errors of the mean frequencies of a healthy group of middle-aged participants from another study (unpublished data, Michel, Paelecke-Habermann, & Leplow, 2008). These data were used for discussion of the results only. a: feedback vs. observation condition b: first vs. second half of the feedback condition.

Fig. 3

Corrected means and standard errors of the error rates for the groups (black: Low-risk Drinker, Binge Drinker, Alcohol Dependent Patients) and both conditions of the CPT. The light grey bars show means and standard errors of the mean error rates of a healthy group of middle-aged participants from another study (unpublished data, Michel et al., 2008). These data were used for discussion of the results only. CE = commission error; CPT Card Playing Task; OE = omission error; PALR = passive avoidance with loss of reward; RRI = reward for response inhibition.