GHRL and Alzheimer disease: • Mitigates AD cognitive damage• Bifidobacterium spp. ↑, Campylobacterales↓• Acetic, propionic and butyric acids↑• IL-1α, IL-1β, IL2, IL-12, IFN-γ, and TNF-α↓• Ghrelin, leptin, GLP-1 and GIP↑• Aβ1–42↓