Alzheimer's disease (AD) is a progressive neurodegenerative disorder driven by multifactorial mechanisms. Increasing evidence suggests that dysbiosis, a term denoting an imbalance in the composition of the microbiota, may play a pivotal role in the pathogenesis of AD across multiple bodily sites, including the gut, oral cavity, nasal passages, lungs, and skin. Microbial imbalances may promote neuroinflammation, immune dysfunction, and metabolic disturbances through complex host-microbiota networ