Alzheimer's disease (AD) is a neurodegenerative disease and main form of dementia, charac-terized by progressive cognitive decline and detrimental consequences in both personal-family and global level. Within this narrative review, we provide recent molecular aspects of Tau, a microtubule AD-associated protein as well as amyloid beta, involved in AD pathophysi-ology. Moreover, we provide additional emerging data from basic research as well as clinical studies indicating an implicating role of gastrointestinal microbiota (GIM), including Helicobac-ter pylori infection (Hp-I), in AD pathophysiology. Likewise, we identify through a molecular prism the current evidence of AD pathogenesis as well as its linkage with GIM and emphasiz-ing the role of Hp-I. Furthermore, metabolic syndrome, the epidemic of mainly western socie-ties, is also related with alterations of GIM and Hp-I, which might in turn influence in a molecu-lar, immunological and endocrinological way the pathogenesis of AD. All in all, additional large-scale studies are required for the further clarification of AD pathophysiology and its connec-tion with GIM and and Hp-I, so as novel therapies on molecular basis become available.