Ruijin Neurobank of Alzheimer's Disease and Dementia

Inclusion Criteria: 1. Male and female aged 50 to 90 years old; 2. In accordance with the diagnostic criteria for "mild cognitive impairment due to Alzheimer's disease" and "Dementia" from the National Institutes of Health National Institute on Aging-Alzheimer's Association (NIA-AA) (2011); 3. The Hamilton depression rating scale/17 edition (HAMD) total score\<10; 4. The clinical dementia rating (CDR) is 0.5 or above; 5. Neurological examination: no obvious signs; 6. Participants should have a caregiver stable and reliable. 7. Education: primary school (grade 6) or above. They have the ability to complete tests for cognitive ability and have the ability and time to complete regulation of cognitive training Exclusion Criteria: 1. Other causes of cognitive decline: cerebrovascular disease, central nervous system infection, CJD, Huntington's and Parkinson's disease, DLB, traumatic brain dementia, other physical and chemical factors (such as drugs, alcohol, CO), systemic disease (hepatic encephalopathy, pulmonary encephalopathy, etc.), intracranial occupation (a subdural hematoma, brain tumor), the endocrine system disease (thyroid disease, parathyroid disease), and vitamins deficiency or any other causes of dementia. 2. The history of nervous system diseases, including stroke, optic myelitis, Parkinson's disease, epilepsy, etc.); 3. Psychiatric patients, including schizophrenia or other mental illnesses, bipolar disorder, major depression, or delirium; 4. There are unstable or serious heart, lung, liver, kidney, and hematopoietic system diseases; Poor prognosis because of malignant diseases such as tumors. 5. Vision or hearing problems that lead to poor performance on cognitive tests; 6. Two years history of severe alcoholism, and drug abuse; 7. The researchers believe that the subjects could not complete the study. 8. Contraindication of MRI or PET scanning.