Effect of Serotonergic Stimulation on the Gut-brain Axis

In this double-blinded, randomized, cross-over study, irritable bowel syndrome subjects (n = 40) and healthy controls (n = 20) will perform an emotional and the arithmetic task and receive visceral stimuli (by using a barostat) while placed in a functional magnetic resonance imaging scanner respectively during two different states, a) after oral administration of 10 mg Escitalopram, a well-known drug classified as Selective Serotonin Reuptake Inhibitor, packed in a coloured hydroxypropylmethylcellulose capsule, and b) during oral administration of a placebo, in a double-blinded randomized cross-over fashion. Background characteristics will be collected.

Inclusion criteria

for the irritable bowel syndrome group:

• Subjects fulfill Rome IV diagnostic criteria for irritable bowel syndrome and pain frequency for at least 1 day per week in the last 12 weeks
• Males or females aged 18-65 years
• Signed informed consent

Exclusion criteria

for the irritable bowel syndrome group:

• Concurrent or recent treatment with drugs affecting intestinal microbiota, function or mood, e.g., antidepressants (< 12 weeks), antibiotics (< 12 weeks)
• Concurrent or recent (< 4 weeks) use of nutritional supplements or herb products affecting intestinal function or mood (e.g. aloe vera, St. John´s Wort and probiotics)
• Diagnosis of major psychiatric or somatic disease other than part of irritable bowel syndrome
• Suicidal tendencies according to Montgomery Åsberg Depression Ratings Scale and/or clinical judgment
• Abuse of alcohol or drugs according to Alcohol Use Disorders Identification Test, and/or clinical judgment
• Recent (< 4 weeks) intake of proton pump inhibitors (e.g., omeprazole)
• Epilepsy
• Cerebral bleeding or history of cerebral bleeding
• Pregnancy or breastfeeding (will be asked)
• Claustrophobia
• Smoking or using tobacco including snuff
• Dominant left-hand
• Medical implant (e.g., pacemaker)
• Aneurysm clips in the head
• Shunts in the head
• Grenade-splinter or metal-splinter in the body (e.g., eyes)
• Metal or electrodes in the body (e.g., temp-catheter, aorta stent, cochlear implant)
• Comprehensive tooth-implants or prothesis
• Operated in the head
• Operated in the heart
• Swallowed a video-capsule
• Non-corrected astigmatism
• Regular intake of antiinflammatory medication (including non-steroidal antiinflammatory drugs)
• Visual defect without possibility to use lenses during functional magnetic resonance imaging scanning
• Any other reason the investigator feels the subject is not suitable for participation in the study

Inclusion criteria

for healthy group:

• Males and females aged 18-65 years of age
• Signed informed consent

Exclusion criteria

for the healthy group:

• Concurrent or recent history of gastrointestinal disorders or any somatic disorder
• Concurrent or recent treatment with drugs affecting intestinal microbiota, function or mood, e.g., antidepressants (< 12 weeks), antibiotics (< 12 weeks)
• Concurrent or recent (< 4 weeks) use of nutritional supplements or herb products affecting intestinal function or mood (e.g. aloe vera, St. John´s Wort and probiotics)
• Concurrent psychiatric or psychological symptomatology defined as above cut-off on Montgomery Åsberg Depression Ratings Scale, above clinical cut-off on hospital anxiety and depression scale (equal to or above 8)
• Abuse of alcohol or drugs according to Alcohol Use Disorders Identification Test, and/or clinical judgment
• Recent (< 4 weeks) intake of proton pump inhibitors, (e.g., omeprazole)
• Epilepsy
• Cerebral bleeding or history of cerebral bleeding
• Pregnancy or breastfeeding (will be asked)
• Claustrophobia
• Smoking or using tobacco including snuff
• Dominant left-hand
• Medical implant (e.g., pacemaker)
• Aneurysm clips in the head
• Shunts in the head
• Grenade-splinter or metal-splinter in the body (e.g., eyes)
• Metal or electrodes in the body (e.g., temp-catheter, aorta stent, cochlear implant)
• Comprehensive tooth-implants or prothesis
• Operated in the head
• Operated in the heart
• Swallowed a video-capsule
• Non-corrected astigmatism
• Intake of anti-inflammatory medication (including non-steroidal antiinflammatory drugs)
• Visual defect without possibility to use lenses during functional magnetic resonance imaging scanning
• Any other reason the investigator feels the subject is not suitable for participation in the study.