Alzheimer’s disease (AD) is a critical issue that affects both the quality of life of families and public health. Despite years of research, single-target therapies for AD remain limited. This is primarily because of the complex and multifaceted pathological mechanisms underlying AD. Recent findings of the involvement of gut microbiome dysbiosis in AD pathogenesis have offered novel insights, emphasizing the need for holistic approaches. As AD progresses, gut microbiota alterations contribute to metabolic and immune imbalances, sparking peripheral inflammation. Consequently, there is heightened infiltration of immune cells into the brain, thus exacerbating neuroinflammation and cognitive decline. Notably, drug developments targeting this mechanism have witnessed substantial advancements, presenting novel systematic treatment approaches for AD patients. Furthermore, the gut microbiota plays a pivotal role in many other diseases and their associated cognitive impairments. The gut-brain axis, a bidirectional communication network, therefore holds significant promise for AD treatment as well as broader cognitive impairment solutions, beyond those based on the amyloid-beta and tau theories.