Preliminary clinical trial results indicate that Aβ-targeting monoclonal antibody drugs can delay disease progression more effectively. However, some patients still progress slowly to the moderate stage during treatment despite maintaining low Aβ/tau pathological protein loads. For such cases, patients and their families are fully informed about the potential lack of efficacy with continued treatment, and the decision is left to their discretion. Information regarding whether treatment is continued is documented and followed up to determine whether sustained benefits can be achieved. Previous further studies on lecanemab suggest that patients with low or absent tau pathology derive more significant clinical benefits, though large-sample validation remains lacking. This project will therefore enroll patients at clinical stages 3-4 (0.5 ≤ CDR ≤ 1) and monitor those progressing to moderate AD (CDR = 2) during monoclonal antibody therapy. Using tau pathology stratification, the study aims to identify which AD patients are most suitable for monoclonal antibody treatment and evaluate whether therapy continuation yields sustained benefits in patients progressing to moderate dementia, as well as whether patient selection should integrate both pathological (a-c stage) and clinical diagnoses.

Inclusion Criteria:

• Meet the diagnostic criteria for Mild Cognitive Impairment (MCI) due to Alzheimer's Disease or mild-to-moderate AD. [Clinical Scores: CDR Global Score = 0.5 (for MCI) or 1 (for mild AD), corresponding to clinical stages 3-4, with a positive PIB-PET scan confirming amyloid pathology]
• Male or Female
• Between 50 and 85 years old (inclusive)
• Not currently participating in any other clinical trial or research study
• Participants must provide informed consent for this trial prior to enrollment and must voluntarily sign a written informed consent form
• Participants must be able to communicate effectively with the investigator and are expected to comply with the study requirements to completion

Exclusion Criteria:

• Any contraindication to MRI
• History of seizure within the past 6 months or refractory epilepsy.
• Unstable or severe psychiatric illness within the past 6 months.
• History of bleeding disorders, coagulopathy, or clinically significant coagulation abnormalities (e.g., platelet count <50,000/μL or INR >1.5).
• Uncontrolled diabetes mellitus or hypertension.
• History of unstable angina, myocardial infarction, advanced heart failure, or clinically significant conduction abnormalities within the past year.
• Active cancer treatment (e.g., chemotherapy, biologics, or radiation therapy), except maintenance therapy for cancers in remission (e.g., anti-estrogen therapy for breast cancer).
• Immunological disorders requiring ongoing immunosuppression, immunoglobulin therapy, monoclonal antibodies, or plasmapheresis.
• Breastfeeding individuals or women of childbearing potential not using highly effective contraception.
• History of severe allergic, anaphylactic reactions, or hypersensitivity to any inactive ingredients.

This study included early AD patients treated with Lecanemab and Conventional Anti-Dementia Treatment at the Second Affiliated Hospital of Zhejiang University School of Medicine.