To enhance understanding of the complex metabolite-mediated mechanisms linking gut dysbiosis to AD pathogenesis, Table 3 offers an integrated summary of how specific microbial metabolites converge on three critical pathophysiological domains: microglial activation and neuroinflammation, insulin signaling and metabolic dysfunction, and blood–brain barrier integrity—each representing a targetable therapeutic node in the gut-brain axis. The gene discussed is INS; the disease is Alzheimer disease.