Effect of Social Isolation on the Role of Pavlovian Mechanisms for Control Over Alcohol Use

Overview

During the first funding period (1st FP) we investigated the impact of acute and chronic stress (Trier Social Stress Test, TSST) on Pavlovian-to-instrumental transfer (PIT). Moreover, we developed a novel full transfer task that allows assessing both general and specific PIT to investigate whether specific PIT differs between alcohol use disorder (AUD) and control subjects. We found that our online version of TSST induced stress and thereby amplified PIT effects in participants. Preliminary analyses of the full transfer task indicate that AUD participants exhibit a stronger specific PIT effect compared to controls. Based on these findings, we want to assess the following aim for this study: Investigate the effect of experimentally induced social exclusion on alcohol-specific and general PIT effects in AUD and control participants.

The projects research aim: The investigators will examine how an experimentally induced social exclusion by the Cyberball task is associated with alcohol specific and general PIT effects by using the newly developed full transfer task from 1st funding period in AUD vs. HCs. The investigators will use the newly developed full PIT paradigm to examine the modifying effect of experimentally induced social exclusion stress on alcohol-specific and general PIT effects. While using the Trier Social Stress Test in the 1st FP, the investigators now want to go one step further by including social exclusion/ostracism to the stress component, which has not been studied in association with PIT effects yet. The investigators here want to shed light on possible underlying mechanisms which can lead to a promotion of alcohol-seeking by alcohol-stimuli in situations of social exclusion. Participants (50 AUD and 50 HC) will be assessed at two time points, once after experimentally induced social exclusion and once after social inclusion in a fully balanced, cross-over within-subject design. Subjects will play an online game tossing a ball to each other with two more virtual co-players (Cyberball). Using a cover story, we make subjects believe that the co-players really exist and that they play a live online game. During social exclusion, subjects will be systematically excluded by one co-player (partial exclusion), and during social inclusion, ball tosses will be balanced between all three players. Cyberball usually induces feelings of social isolation and altered behavioral reactions in the subject, which the investigators want to assess by analyzing ball tossing behavior over time, as well as physiological and subjective measures (concentration of cortisol in saliva, heart rate variability and emotions questionnaires, such as the Need to Belong Scale, Rejection Sensitivity Questionnaire, Need threat scale and Positive and Negative Affect Schedule pre and post Cyberball game and after PIT). After the Cyberball experiment, subjects will undergo the transfer part of the full PIT task (using a parallel version at one of the two days in a randomized order). Hypothesis 1a: Social exclusion will lead to a stronger stress hormone response (concentration of cortisol in saliva), lower heart rate variability and a stronger general PIT effect compared to social inclusion (main effect social exclusion intervention on PIT). Hypothesis 1b: Stronger social exclusion effects in AUD subjects compared to controls will lead to stronger PIT effects compared to social inclusion (interaction effect between group and stress intervention on PIT), especially for alcohol-specific PIT.