Probiotic Research for Mental Health in Adult Volunteers

Participants complete a virtual reality-based assessment (VIRDIS) and rate their level of unpleasantness following exposure to a predefined social scenario. Unpleasantness is assessed on a 5-point scale ranging from 1 (not at all unpleasant) to 5 (very unpleasant).

This outcome comprises the mean unpleasantness score across all VR scenarios in the VIRDIS test on a scale ranging from 1 (not at all unpleasant) to 5 (very unpleasant).

Heart rate is measured during the VIRDIS assessment (using a wearable physiological monitoring device). Heart rate (pulse) is reported in beats per minute (bpm). Higher scores indicating higher heart rate.

The SF-36 questionnaire will be administered in its entirety. The Energy/Vitality subscale (items 23, 27, 29, and 31) is designated as a secondary outcome measure.

Heart rate variability is measured during the VIRDIS assessment (using a wearable physiological monitoring device). HRV is derived from the variation in time between consecutive heartbeats (interbeat intervals).

Skin conductance (electrodermal activity) measured during the VIRDIS assessment. Outcomes include tonic and phasic skin conductance measures reported in microsiemens (µS).

Pupil dilation is measured during the VIRDIS assessment using integrated eye-tracking technology. The outcome is reported as change in pupil diameter (mm).

Eye-tracking technology integrated into the VIRDIS assessment records gaze behavior during the virtual reality scenarios. This outcome is reported as the mean gaze velocity (°/s), i.e., average angular velocity of eye movements recorded throughout the virtual reality assessment. Unit of measure: degrees/second (°/s).

Eye-tracking technology integrated into the VIRDIS assessment records mean saccade amplitude in the virtual reality scenarios measures as the average angular distance of saccadic eye movements (i.e., rapid eye movement between two points of focus). Unit of measure: degrees

The SF-36 is a self-administered quality of life questionnaire comprising 36-items measuring eight health domains: physical functioning (10 items), role limitation due to physical health problems (4 items), bodily pain (2 items), general health perceptions (5 items), vitality (4 items), social functioning (2 items), role limitations due to emotional problems (3 items), and general mental health (5 items). These outcomes will be grouped as physical component summary and mental component summary. The norm data is 0-100, the health-related quality of life increases as the scores increase. The average score is 50.

Questionnaire on quality of life. Part A score range: 5-15. Part B: VAS scale: 0-100.

Questionnaire assessing subjective sleep quality. Outcomes include the global PSQI score (range 0-21) and the seven component scores: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleep medication, and daytime dysfunction. Higher scores indicate poorer sleep quality.

Questionnaire on perceived stress. Score range 0-40.

Questionnaire on depressive symptoms. Score range 0-72.

Questionnaire on cognitive difficulties. Score range 0-48.

Questionnaire on anxiety. Score range 20-80.

Questionnaire on attentional control. Score range 12-48.

Questionnaire on emotion regulation. Score range 7-49.

Questionnaire on emotion regulation. Score range 0-144.

Questionnaire on emotion regulation. Score range 0-72.

Computerized test assessing visuospatial memory and new learning. The main outcome is the total number of errors (incorrect boxes selected) made across all stages, adjusted to account for stages not completed.

A computerised neuropsychological test assessing sustained attention. The outcome measure is A-prime (A'), which measures target sensitivity (sustained attention). score range 0-1.

A computerised neuropsychological test assessing spatial working memory. The main outcome is the number of times a participant revisits a box that has already been opened and found to be empty in a specific trial.

A computerized emotional processing task in which participants categorize positive and negative personality trait words according to whether they would like or dislike being described by each characteristic. Following the categorization task, participants are asked to recall as many words as possible.

Computerized emotional processing task assessing valence bias during evaluation of emotional facial expressions. The primary outcome is valence bias, defined as the percentage of ambiguous surprised faces rated as "bad."

Computerized task assessing emotional reactivity and emotion regulation in response to positive, negative, and neutral social scenarios. The outcome measure is emotional response rated on a 100-point visual analogue scale (VAS) of discomfort or pleasure.

Computerized task assessing recognition of emotional facial expressions. The outcome measure is emotion recognition accuracy, defined as the proportion of correctly identified emotional expressions.