Diagnosis of a dementia-related central nervous system disease other than AD.

Major structural brain disease as judged by MRI.

A resting heart rate of \< 50 beats per minute (bpm) after 5 minutes of rest in sitting or supine position.

Major medical illness or unstable medical condition within 6 months of screening.

Concomitant use of AChEIs and/or memantine within 30 days before first MMSE score, and during the study.

Inadequate hepatic function.

Inadequate organ and marrow function.

ECG clinically significant abnormalities.

A Study of Sodium Oligomannate (GV-971) in Participants With Mild to Moderate Alzheimer's Disease