Inclusion Criteria:  Patients or their families complain of significant memory impairment; Objective memory impairment (e.g., tests of article identification, recall, delayed memory); Meets Alzheimer's criteria for DSMIV and NINCDS-ADRDA; Be able to obtain complete diagnosis and treatment records and be able to carry out long-term follow-up; Signed written consent.  Exclusion Criteria:  Nervous system diseases: including brain tumors, craniocerebral trauma, multiple sclerosis, epilepsy, etc.; Psychiatric disorders: including anxiety disorder, affective disorder, severe psychosis, or drug-induced psychosis; Pregnancy or lactation.