This project is a multicenter observational study that establishes a longitudinal cohort of patients with Alzheimer's disease and other dementias based on neuroimaging, molecular imaging, biological and digital markers to explore new solutions such as dementia disease mechanism, diagnosis, condition evaluation, and prognosis assessment.

This project will build a longitudinal database based on multimodal MRI imaging information of dementia subjects, various body fluid or digital markers, and a cohort. The convolutional neural network algorithm will be used to explore the imaging characteristics of healthy controls, AD, FTD, and DLB, develop an early prediction model for degenerative dementia, and achieve early differential diagnosis of different dementia subtypes. This study further performed GE180, ASEM, and exendin-4 radionuclide imaging on some subjects who completed conventional PET (AV45, Tauvir, and FDG) imaging to explore the diagnostic efficacy of these three probes as new diagnostic probes for early AD. In addition, through longitudinal follow-up of Aβ-positive MCI patients, multimodal MRI and PET image fusion technology were used to explore the changes in fused images during their conversion to AD in order to obtain early and accurate diagnostic markers.

Inclusion Criteria:

• Patients aged ≥50 and ≤85 years old, male or female;
• Meet the diagnostic criteria for dementia or MCI;
• Neuropsychological score: MMSE 15-28 points, CDR ≤ 1 point; ④ Patients and their families are informed and sign the informed consent form

Exclusion Criteria:

• The presence of other neurological diseases that may cause brain dysfunction (such as depression, brain tumors, Parkinson's disease, metabolic encephalopathy, encephalitis, multiple sclerosis, epilepsy, brain trauma, normal intracranial pressure hydrocephalus, etc.);
• The presence of other systemic diseases that may cause cognitive impairment (such as liver dysfunction, renal dysfunction, thyroid dysfunction, severe anemia, folic acid or vitamin B12 deficiency, syphilis, HIV infection, alcohol and drug abuse, etc.);
• Suffering from a disease that makes it impossible to cooperate with cognitive examinations;
• The presence of contraindications to MRI;
• The presence of mental and neurological retardation;
• Refusing to draw blood;
• Refusing to sign the informed consent form.

The population in this study includes the cognitive impairment patients in Ruijin Hospital, Renji Hospital, The First Hospital of Zhejiang University School of Medicine, The First Hospital of China Medical University.