Beyond the complex microbiology these researchers are doing, there’s an even more direct way your gut influences your brain.
Imagine the effect on your psyche if you can never go on a long walk on the beach, or go scuba diving, or sit through a longish movie without missing part of it, or any of the other pleasurable activities that require you to be too far from a toilet because diarrhea might strike at any moment. Imagine scanning every street you walk down and road you drive on for thick bushes or someplace else you could potentially hide. Imagine having to interrupt sex to go noisily destroy the bathroom. Imagine this going on for years.
I don’t doubt that gut flora has some effect on neurology, but the lowered quality of life associated with “stomach problems” can itself be a significant negative influence on mental health.
