Mechanism

IBS

FD

Visceral hypersensitivity

+++

+++

Upper Gastrointestinal dysmotility

+

+++

Lower Gastrointestinal dysmotility

+++

+

Brain Processing abnormalities

++

?

Genetics

+

+

Psychiatric comorbidities

++

+

Post-infection

++

+

Serotonin Signalling abnormalities

+

+