Long before memory falters or a name is forgotten, the brain may already be changing — and now, researchers suggest the gut may be changing alongside it. A review published in Nutrients draws together evidence that shifts in gut bacteria, particularly those that produce protective short-chain fatty acids, may accompany the earliest biological signs of Alzheimer's disease, years before any cognitive symptom appears. The findings do not yet prove causation, but they point toward a quiet frontier: the possibility that what we eat may one day be part of how we intervene before the disease announce