I believe the opposite is actually applied in practice, e.g. prescribing antidepressants to people with IBS for instance where the physical cause of the bowel s

I believe the opposite is actually applied in practice, e.g. prescribing antidepressants to people with IBS for instance where the physical cause of the bowel symptoms isn't obvious/is suspected to be neurologically related. From the point of view of somebody with IBD, negative cognitive effects in the middle of a flare seem pretty "common sense" obvious but it could also be down to dehydration etc... But that's in the case where there is a specific physical gut disease process in progress. I imagine that treating mental health conditions by altering the gut in people who have healthy bowels is probably a dead end.