Long-term Efficacy and Safety Study of GV-971

Inclusion Criteria: 1. Aged 50 to 85 years (inclusive), with no restriction on gender; 2. Patients who met criteria for "probable AD" by National Institute on Aging and Alzheimer's Association (NIA-AA) diagnostic criteria; 3. Patients with mild to moderate AD as characterized by Mini-Mental State Examination (MMSE) scores between 11 and 26, inclusive; 4. 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; 5. Patients receiving GV-971 treatment prescribed by clinicians; 6. Sign the informed consent form. Exclusion Criteria: 1. Patients who have received GV-971 treatment within 6 months prior to screening; 2. Patients who may be allergic to Sodium Oligomannate Capsules as judged by the investigator; 3. Female participants who are pregnant or lactating; 4. Patients who cannot cooperate to complete the follow-up inquiries; 5. Any other diseases or conditions that are inappropriate to participate in this clinical trial in the opinion of the investigator.