• Aged 50-80 years.

• Clinical diagnosis of probable mild Alzheimer disease dementia based on National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association (NINCDS/ADRDA criteria, 2011)

• Last time (which must be within 3 months ) of Mini Mental State Exam (MMSE) between 10-26.

• Last time (which must be within 3 months) of Clinical Dementia Rating (CDR) score of 1.

• Physically healthy and all laboratory assessments (including hematology, chemistry, urinalysis and electrocardiograph) are within normal range or meet the following criteria:

‣ AST, ALT level ≦ upper limit of normal

⁃ Creatine Kinase (CK) concentration more than 3 times upper limit of normal

⁃ Serum creatinine level ≦ upper limit of normal

⁃ HbA1c more than 8.0

• Complaints of subjective memory impairment and cognitive disturbances by patients themselves or caregivers, including memory loss and at least one of the following cognitive disturbances: language, perceptual skills, attention, constructive abilities, orientation, problem solving, functional abilities.

• Cognitive deficits caused impairment in social or occupational function.

• Disease progression with gradual and continued decline from a previous level of functioning.

• Female subjects must be of non-childbearing potential (greater than 1 year without menstrual period in the absence of hormone replacement therapy) or surgically sterile. If pre-menopausal or menopausal for 1 year or less, must have a negative pregnancy test and must not be lactating at screening visit. Female subjects of childbearing potential and who are sexually active are required to practice adequate methods of birth control. Male subjects who are sexually active will also be required to use an adequate form of birth control.

• Has sufficient education equivalent to elementary education to communicate effectively and were capable of completing the assessments of the study.