From July 26 to 30, the 2021 the Alzheimer’s Association International Conference (AAIC) 2021 was convened in Denver, the US. Combining both online and offline forms, the event brought together the world's leading basic science and clinical researchers, clinicians, and nursing research groups, attracting more than 11,000 attendees and over 3,000 scientific presentations to share and exchange newest research findings on the prevention, diagnosis and treatment of Alzheimer's disease (AD) and other dementias. The symposium “The Interplay of Systemic Factors in Alzheimer’s Disease” was hold on July 27. A number of Chinese and international experts were invited to conduct in-depth discussions, who also shared latest findings to reveal the relationship between AD and the gut microbiota.