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.