that a bacteria decided to "lemme make this dude ask a question on HN". On a serious note, it's already answered in the article - it means that our behavior is not only influenced by the gut bacteria (already proven), but the brain ones too.

Well finally I have a new excuse to ask dumb questions here...

But what I mean is, what are the downstream consequences of this knowledge? Does it change how we can reason about health, cognition, etc?

unknown. they barely suspect this, to your question is another leap in science for future generations of researchers