Brain responses to emotional salience and reward in alcohol use disorder

Abstract

Heightened neural responsiveness of alcoholics to alcohol cues and social emotion may impede sobriety. To test mesocorticolimbic network responsivity, 10 (8 men) alcohol use disorder (AUD) patients sober for 3 weeks to 10 months and 11 (8 men) controls underwent fMRI whilst viewing pictures of alcohol and non-alcohol beverages and of emotional faces (happy, sad, angry). AUD and controls showed similarities in mesocorticolimbic activity: both groups activated fusiform for emotional faces and hippocampal and pallidum regions during alcohol picture processing. In AUD, less fusiform activity to emotional faces and more pallidum activity to alcohol pictures were associated with longer sobriety. Using graph theory-based network efficiency measures to specify the role of the mesocorticolimbic network nodes for emotion and reward in sober AUD revealed that the left hippocampus was less efficiently connected with the other task-activated network regions in AUD than controls when viewing emotional faces, while the pallidum was more efficiently connected when viewing alcohol beverages. Together our findings identified lower occipito-temporal sensitivity to emotional faces and enhanced striatal sensitivity to alcohol stimuli in AUD than controls. Considering the role of the striatum in encoding reward, its activation enhancement with longer sobriety may reflect adaptive neural changes in the first year of drinking cessation and mesocorticolimbic system vulnerability for encoding emotional salience and reward potentially affecting executive control ability and relapse propensity during abstinence.

Keywords: Alcohol use disorder; Emotion; Face processing; Functional connectivity; Mesocorticolimbic; Reward; Sobriety; fMRI.

Figure 1. Brain activation elicited by expressions of facial emotion and alcohol beverage pictures

Top panel. A. Conjunction analysis showing the group overlap (AUD=CTL) of activations for the alcohol beverage pictures (red), emotional faces (yellow) and regions activated by both, alcohol-related and emotional face pictures (orange) using a peak threshold of p_{FWE-corrected}<0.05. Bottom panel. B. Group differences in activations to alcohol beverage picture viewing for AUD > CTL (red) and the interaction between group (CTL>ALC) and beverage type (alcohol > no-alcohol) (blue). Group differences in activation to emotional faces for AUD > CTL (yellow) and for CTL > AUD (green) using a peak threshold of p_uncorrected<0.001. Abbreviations: Alcohol Use Disorder (AUD), age-matched controls (CTL).