Combining Cognitive Training With tDCS to Enhance Memory Inhibition in Young Binge Drinkers

This study protocol aims to examine the behavioral and electroencephalographic (EEG) correlates of memory inhibition (MI) among college binge drinkers (BDs). A second objective is to evaluate an alcohol-specific MI training protocol using cognitive training (CT) and transcranial direct current stimulation (tDCS) while its effects on behavioral and EEG outcomes are assessed. Along with poor MI abilities, we hypothesized that BDs would show alterations in the amplitude of several event-related potentials (ERPs) linked to MI (e.g., N2 and late parietal positivity) as well as abnormal functional connectivity (FC) patterns within/between regions associated with MI (e.g., dorsolateral prefrontal cortex \[DLPFC\] and hippocampal/parahippocampal regions). Results should also demonstrate the effectiveness of the training protocol, with BDs exhibiting an improved capacity to suppress alcohol-related memories after both combined and cognitive MI training, along with a significant reduction in alcohol use and craving in the short/medium-term. Furthermore, this protocol should also lead to significant modifications in the ERP and FC patterns, reflecting stronger MI capabilities and reduced alcohol cue reactivity in trained BD participants.

The present study protocol aims to examine the behavioral and EEG correlates of MI, specifically those related to the suppression of alcohol-related memories, among young BDs. For this purpose, 45 BDs and 45 age-matched non/low-drinkers (N/LDs) will be assessed by EEG while performing the Think/No-Think Alcohol (TNTA) task, a paradigm that evaluates alcohol-related MI (Pre-training EEG assessment). The TNTA is divided into three phases: 1) the Learning phase, 2) the Think/No-Think (TNT) phase and 3) the Memory-Test phase. During the learning phase, participants will be asked to associate and memorize 36 pairs of neutral objects + alcoholic/non-alcoholic pictures. Then, only the neutral objects will be presented, and participants will have to try to remember the picture (alcoholic/non-alcoholic image) that was associated with this neutral object and answer three questions about the beverage depicted, the orientation of the picture and the number of people present in it. After the learning phase, the Think/No -Think phase will comprehend two conditions: in the Think condition (depicted in the neutral images with a green frame),participants are presented with the object and they will be instructed to "think of the previously learned alcoholic/non-alcoholic picture and keep it in mind during the entire presentation of the object". In the No-Think condition (depicted by neutral images with a red frame) they will be asked "not to let the previously associated picture enter your consciousness". In the memory test phase, the 36 neutral images will be presented again, including the 12 neutral objects of the baseline condition that were not presented in the TNT phase. Participants will be asked to recall - answering the same three questions of the learning phase - the image (alcoholic/non-alcoholic) that was initially associated with the neutral object.

During this pre-training session, psychological (i.e., craving levels), behavioral (i.e., alcohol consumption, recall accuracy and MI performance), and neurofunctional (i.e., ERPs and FC) variables will be assessed.

In addition, this study aims to evaluate an alcohol-specific MI intervention protocol using cognitive training and tDCS while its effects on behavioral and EEG outcomes are assessed. For that, BDs will be randomly assigned to one of three training groups: combined intervention (active CT and active tDCS applied over the right DLPFC), cognitive intervention (active CT and sham tDCS), or control intervention (sham CT and sham tDCS). Training will occur in three consecutive days (i.e., Tuesday, Wednesday, and Thursday), in three sessions. MI will be re-assessed in BDs after the last training session through a post-training EEG assessment. N/LDs will only perform the pre-training EEG assessment. Alcohol use and craving will also be measured both 10-days and 3-months post-training in order to monitor short- and medium-term effects of the MI training in the alcohol craving and consumption levels. Furthermore, behavioral and EEG data will be collected during the performance of an alcohol cue reactivity (ACR) task before and after the MI training sessions, in order to evaluate potential attentional bias towards alcoholic stimuli. Overall, this intervention protocol aims to investigate whether this training is able 1) to enhance MI capabilities and to reduce alcohol attentional bias, and 2) to decrease craving and/or alcohol use -monitoring up to three months after protocol implementation- in trained BD participants.

Eligibility Criteria:
Inclusion Criteria:

* College students
* Age 18-24 years
* Binge Drinkers: report (i) drinking 5 or more drinks on one occasion at least once a month, and (ii) drinking at a speed of at least two drinks per hour during these episodes (which brings blood alcohol concentration to 0.08 gram percent or above).
* Non/Low-Drinkers: report (i) never drinking 5 or more drinks on one occasion and (ii) having an AUDIT score ≤ 4.

Exclusion Criteria:

* Use of illegal drugs except cannabis (as determined by the Drug Use Disorders Identification Test-Extended \[DUDIT-E; Berman, Bergman, Palmstierna \& Schlyter, 2007);
* Alcohol abuse (i.e., AUDIT ≥ 20);
* Consumption of medical drugs with psychoactive effects (e.g., sedatives or anxiolytics) during the two weeks before the experiment;
* Personal history of psychopathological disorders (according to DSM-V criteria);
* History of traumatic brain injury or neurological disorder;
* Family history of alcoholism or diagnosis of other substance abuse;
* Occurrence of one or more episodes of loss of consciousness for more than 20 minutes;
* Non-corrected sensory deficits;
* Global Severity Index (GSI) \> 90 (Symptom Checklist-90-Revised questionnaire \[SCL-90-R\]; Derogatis, 1983) or a score above 90 in at least two of the symptomatic dimensions.