Investigating the Impact of Probiotics on Wellbeing in a Community

Everyday cognitive functioning will be assessed using the Cognitive Failures Questionnaire 2.0 (CFQ 2.0), a 15-item self-report questionnaire measuring the frequency of cognitive lapses in daily life (e.g., memory, attention, and action errors). Each item is rated on a 5-point scale. Total scores are calculated by summing all item responses, yielding a score ranging from 0 to 60. Performance will be measured as the total CFQ 2.0 score (range 0-60), with higher scores indicating greater frequency of cognitive failures.

Gastrointestinal symptoms will be assessed using the Gastrointestinal Symptom Rating Scale (GSRS), a 15-item self-report questionnaire evaluating the severity of common gastrointestinal symptoms. Each item is rated on a 7-point Likert scale, with higher scores indicating more severe symptoms. Total scores are calculated by summing all item responses, yielding a score ranging from 15 to 105. Performance will be measured as the total GSRS score (range 15-105), with higher scores indicating greater gastrointestinal symptom severity. Domain scores may also be calculated by averaging relevant items to assess specific symptom clusters.

Drinking behaviour will be assessed using the Loughborough Alcohol Drinking Questionnaire (LoAD-Q), a 33-item self-report questionnaire measuring three dimensions: emotional drinking, external drinking, and restrained drinking. Each item is rated on a 5-point Likert scale (1 = never to 5 = very often). Subscale scores are calculated by summing item responses within each dimension.

The emotional drinking subscale (13 items) has a score range of 13 to 65, the external drinking subscale (10 items) ranges from 10 to 50, and the restrained drinking subscale (10 items) ranges from 10 to 50. Performance will be measured as subscale total scores, with higher scores indicating greater levels of emotional, external, and restrained drinking behaviour, respectively.

Mental health symptoms will be assessed using the Depression Anxiety Stress Scales-12 (DASS-12), a 12-item self-report questionnaire measuring symptoms of depression, anxiety, and stress. Each item is rated on a 4-point Likert scale (0-3), yielding a total score ranging from 0 to 36. Performance will be measured as the total DASS-12 score (range 0-36), with higher scores indicating greater psychological distress.

Alcohol craving will be assessed using the Penn Alcohol Craving Scale (PACS), a 5-item self-report questionnaire measuring frequency, intensity, and duration of alcohol cravings over the past week. Each item is rated on a scale from 0 to 6, yielding a total score ranging from 0 to 30. Performance will be measured as the total PACS score (range 0-30), with higher scores indicating greater alcohol craving severity.

Disordered eating behaviours will be assessed using the Eating Disorder Examination Questionnaire Short Form (EDE-QS), a 12-item self-report questionnaire measuring eating disorder psychopathology over the past 7 days. Each item is rated on a 4-point scale (0-3), yielding a total score ranging from 0 to 36. Performance will be measured as the total EDE-QS score (range 0-36), with higher scores indicating greater severity of disordered eating behaviours.