Inclusion Criteria:  Aged 50 to 85 years (inclusive), with no restriction on gender; Patients who met criteria for "probable AD" by National Institute on Aging and Alzheimer's Association (NIA-AA) diagnostic criteria; Patients with mild to moderate AD as characterized by Mini-Mental State Examination (MMSE) scores between 11 and 26, inclusive; Patients who have received at least primary education and have capacity to complete the measurement of cognition and other tests as specified in the protocol; Patients receiving GV-971 treatment prescribed by clinicians; Sign the informed consent form.  Exclusion Criteria:  Patients who have received GV-971 treatment within 6 months prior to screening; Patients who may be allergic to Sodium Oligomannate Capsules as judged by the investigator; Female participants who are pregnant or lactating; Patients who cannot cooperate to complete the follow-up inquiries; Any other diseases or conditions that are inappropriate to participate in this clinical trial in the opinion of the investigator.