The Brain, the Bug, and the Binge: the Interplay Between Binge Drinking, Gut Microbiota, and Brain Functioning

Faecal samples will be collected from all participants for microbiota α-diversity analysis by 16S rRNA metagenomics (Illumina sequencing). The Chao1 Index will be used as an estimator of nonparametric microbial species richness in each sample.

Faecal samples will be collected only from binge drinkers subjected to the intervention for microbiota α-diversity analysis by 16S rRNA metagenomics (Illumina sequencing). The Chao1 Index will be used as an estimator of nonparametric microbial species richness in each sample.

Faecal samples will be collected from all participants for microbiota α-diversity analysis by 16S rRNA metagenomics (Illumina sequencing). The Shannon Diversity Index (metric combining richness and evenness, with equal weighting given to abundant and rare species) and the Simpson Diversity Index (metric of richness and evenness, in which more weighting is given to abundant species) will be used.

Faecal samples will be collected only from binge drinkers subjected to the intervention for microbiota α-diversity analysis by 16S rRNA metagenomics (Illumina sequencing). The Shannon Diversity Index (metric combining richness and evenness, with equal weighting given to abundant and rare species) and the Simpson Diversity Index (metric of richness and evenness, in which more weighting is given to abundant species) will be used.

The concentration of short-chain fatty acids (SCFAs) present in each collected faecal sample shall be quantified by High Performance Liquid Chromatography (HPLC).

The concentration of SCFAs present in each collected faecal sample shall be quantified by HPLC.

The AUDIT will be administered to characterize the drinking pattern of the participants. AUDIT scores ≤ 4 reveal low risk of alcohol use; scores between 5 and 20 represent excessive alcohol consumption; and scores ≥ 20 indicate very high risk for alcohol dependence and warrant further diagnostic evaluation for alcohol dependence.

The AUDIT will be administered to characterize the drinking pattern of the participants. AUDIT scores ≤ 4 reveal low risk of alcohol use; scores between 5 and 20 represent excessive alcohol consumption; and scores ≥ 20 indicate very high risk for alcohol dependence and warrant further diagnostic evaluation for alcohol dependence.

Short-term alcohol craving levels will be assessed using the ACQ-SF-R at the present moment. Total minimum score: 1 (low level of alcohol craving); Total maximum score: 7 (high level of alcohol craving).

Short-term alcohol craving levels will be assessed using the ACQ-SF-R at the present moment. Total minimum score: 1 (low level of alcohol craving); Total maximum score: 7 (high level of alcohol craving).

The Delayed Matching to Sample (DMS) from Cambridge Neuropsychological Test Automated Battery (CANTAB) will be used to assess both simultaneous visual matching ability and short-term visual recognition memory, for non-verbalisable patterns.

The Delayed Matching to Sample (DMS) from Cambridge Neuropsychological Test Automated Battery (CANTAB) will be used to assess both simultaneous visual matching ability and short-term visual recognition memory, for non-verbalisable patterns.

The Emotion Recognition Task (ERT) from CANTAB will measure the ability to identify six basic emotions (sadness, happiness, fear, anger, disgust, and surprise) in facial expressions along a continuum of expression magnitude.

The Emotion Recognition Task (ERT) from CANTAB will measure the ability to identify six basic emotions (sadness, happiness, fear, anger, disgust, and surprise) in facial expressions along a continuum of expression magnitude.

The performance of the cognitive domain comprising high-level thinking and decision-making will be assessed through CANTAB, namely the Cambridge Gambling Task (CGT, to assess decision-making and risk behaviour outside a learning context), Intra-Extra Dimensional Set Shift (IED, to assess cognitive flexibility), Spatial Working Memory (SWM, to identify working memory strategies and errors) and Stop Signal Task (SST, to measure response inhibition/impulse control).

The performance of the cognitive domain comprising high-level thinking and decision-making will be assessed through CANTAB, namely the Cambridge Gambling Task (CGT, to assess decision-making and risk behaviour outside a learning context), Intra-Extra Dimensional Set Shift (IED, to assess cognitive flexibility), Spatial Working Memory (SWM, to identify working memory strategies and errors) and Stop Signal Task (SST, to measure response inhibition/impulse control).

The reactivity to alcoholic cues will be assessed using the Alcohol Cue Reactivity (ACR) task. The full task includes a total of 80 trials with 40 alcoholic and 40 non-alcoholic images obtained from the Amsterdam Beverage Picture Set. The emotional responses for each image in terms of valence and arousal task, will be registered using the Self-Assessment Manikin (valence: from 1 = "very unpleasant" to 9 ="very pleasant"; arousal: from 1 = "not arousing" to 9 = "highly arousing") during the ACR task.

The reactivity to alcoholic cues will be assessed using the ACR task. The full task includes a total of 80 trials with 40 alcoholic and 40 non-alcoholic images obtained from the Amsterdam Beverage Picture Set. The emotional responses for each image in terms of valence and arousal task, will be registered using the Self-Assessment Manikin (valence: from 1 = "very unpleasant" to 9 ="very pleasant"; arousal: from 1 = "not arousing" to 9 = "highly arousing") during the ACR task.

Memory Inhibition (MI), specifically alcohol-related MI, will be assessed using the Think/No-Think Alcohol (TNTA) task. Percentage of correct responses (for Think, No-Think and Baseline items) in the TNTA task will be computed according to the following formula: ((number of correctly recalled items)/(number of previously learned items))×100. Correct responses correspond to the items learned during the learning phase and correctly recalled during the memory test phase.

MI, specifically alcohol-related MI, will be assessed using the TNTA task. Percentage of correct responses (for Think, No-Think and Baseline items) in the TNTA task will be computed according to the following formula: ((number of correctly recalled items)/(number of previously learned items))×100. Correct responses correspond to the items learned during the learning phase and correctly recalled during the memory test phase.

Emotional recognition capacity will be assessed through the Emotion Discrimination (ED) task. ED assesses the brain's preconscious and conscious responses to emotional faces. The complete task includes a total of 120 images of human faces (60 men and 60 women), showing the main negative emotions: angry, sadness and fear.

Emotional recognition capacity will be assessed through the ED task. ED assesses the brain's preconscious and conscious responses to emotional faces. The complete task includes a total of 120 images of human faces (60 men and 60 women), showing the main negative emotions: angry, sadness and fear.

Blood samples will be collected from all participants. The presence and abundance of the following cytokines will be analyzed: Tumour Necrosis Factor α (TNF-α) and Interleukins (IL-1β, IL-6, IL-10).

Blood samples will be collected only from binge drinkers subjected to the intervention. The presence and abundance of the following cytokines will be analyzed: Tumour Necrosis Factor α (TNF-α) and Interleukins (IL-1β, IL-6, IL-10).

The TNTA task assesses memory inhibition mechanisms in alcohol-related contexts. It involves three phases - Learning, Think/No-Think and Memory Test - during which participants memorise pairs of images (human faces with a neutral expression and alcoholic/non-alcoholic beverages) and are subsequently instructed to actively recall or suppress these associations.

The TNTA task assesses memory inhibition mechanisms in alcohol-related contexts. It involves three phases - Learning, Think/No-Think and Memory Test - during which participants memorise pairs of images (human faces with a neutral expression and alcoholic/non-alcoholic beverages) and are subsequently instructed to actively recall or suppress these associations.

The EFM task assesses emotional recognition ability and pre-conscious and conscious neural responses to emotional faces and geometric forms. During each trial, participants view three emotional faces or shapes (one on top and two on the bottom, in a triangular configuration) and are instructed to identify the emotion/shape at the top of the screen and match it with the corresponding one at the bottom using handheld response buttons.

The EFM task assesses emotional recognition ability and pre-conscious and conscious neural responses to emotional faces and geometric forms. During each trial, participants view three emotional faces or shapes (one on top and two on the bottom, in a triangular configuration) and are instructed to identify the emotion/shape at the top of the screen and match it with the corresponding one at the bottom using handheld response buttons.

The ACR task assesses the emotional and attentional response to alcoholic stimuli. Participants are shown images of alcoholic and non-alcoholic drinks, interspersed with oddball blocks containing neutral objects, to which they must respond by pressing a button. After viewing all images, participants are asked to rate their emotional responses to the alcoholic or non-alcoholic beverage images in terms of valence, arousal, and desire.

The ACR task assesses the emotional and attentional response to alcoholic stimuli. Participants are shown images of alcoholic and non-alcoholic drinks, interspersed with oddball blocks containing neutral objects, to which they must respond by pressing a button. After viewing all images, participants are asked to rate their emotional responses to the alcoholic or non-alcoholic beverage images in terms of valence, arousal, and desire.