Table 2

Summary of questionnaire measures included in the Bugs and Brains Study

CategoryQuestionnairePhase 1
(screening questionnaire)
Phase 2
(SCID-5-RV interview)
Phase 4 (during sample collection)
Demographic informationPhase 1 Health Questionnaire*
Phase 4 Demographics, Health and Exercise Questionnaire*
Emotional functioningDifficulties in Emotion Regulation Scale56
Mental health and behaviourPsychiatric Diagnostic Screening Questionnaire‡36
Global Assessment of Functioning†37
Social and Occupational Functioning Assessment
Scale†37
Beck Depression Inventory57
Beck Anxiety Inventory58
Adult Self Report59
DietDietary Questionnaire for Epidemiological Studies (DQES)60
Phase 1 Health Questionnaire*
  • Specific diet information (past 4 weeks; eg, gluten-free, specific carbohydrates, FODMAPs, vegetarian).

ExercisePhase 4 Demographics, Health and Exercise Questionnaire*
Quality of life/well-beingThe WHO quality of life assessment- abbreviated version
(WHOQOL-BREF)61
Oral healthThe WHO Oral Health Questionnaire for Adults62
Physical health /medical historyThe Physical Health Questionnaire63
Phase 1 Health Questionnaire*
  • Current bacterial, fungal or viral infection

  • Obesity, hypertension, cardiovascular disease, respiratory disease, diabetes mellitus, liver cirrhosis, fatty liver disease, coeliac disease, other autoimmune disease (eg, rheumatoid arthritis, lupus, etc), and polycystic ovary syndrome

  • Current pregnancy/lactation

  • Mode of birth

  • Medication (past month): antidepressants/anxiolytics, antibiotics, psychotropics, oral or injected steroids, probiotics, prebiotics, synbiotics, dietary supplements including laxatives; other medication (past 2 weeks): NSAIDs, antifungals

Gastrointestinal health/historyRome IV Diagnostic Questionnaire34
Phase 1 Health Questionnaire*
  • Non-surgical procedures related to the digestive system (past 6 months): enema, colonoscopy, gastroscopy, inflammatory bowel disease (eg, ulcerative colitis, Crohn’s disease), short bowel syndrome, and lifetime history of abdominal surgery (eg, appendectomy, ileostomy, bowel surgery, caesarean section, etc)

Phase 4 Demographics, Health and Exercise Questionnaire*
  • Lifetime history of gastric infections: Salmonella, Shigella, Campylobacter, Giardiasis, viruses, other

Stressful life eventsThe Lifetime Incidence of Traumatic Events64
Childhood Trauma Questionnaire65
Substance usePhase 1 Health Questionnaire*
  • Alcohol (past month)

  • Smoking (past month): tobacco cigarettes, vape, e-cigarettes containing nicotine


Illicit drug use (past month)
  • DQES (alcohol consumption in the past year)60

  • *Designed specifically for the Bugs and Brains Study.

  • †Measure completed by researchers, rather than participants.

  • ‡Modified version used, see online supplemental material.

  • DQES, Dietary Questionnaire for Epidemiological Studies; FODMAPs, fermentable oligosaccharides, disaccharides, monosaccharides, and polyols; NSAIDS, non-steroidal anti-inflammatory drugs; SCID-5-RV, Structured Clinical Interview for the Diagnostic and Statistical Manual fifth edition, research version; WHO, World Health Organization.