Most of us have experienced the effects of moods and emotions on our gastrointestinal tract, from "butterflies" in the stomach caused by nervousness to a loss of appetite when we're feeling blue.

In animal studies, boosting serotonin in the cells that line the gut reduced anxious and depressive-like behaviors without causing cognitive or gastrointestinal side effects.

Mental health challenges rarely exist in isolation. Among the most concerning combinations, dementia and depression ...