The Effect of Sequential Therapy on Alzheimer's Disease

Inclusion Criteria: * Age 55 to 85 years, regardless of sex. * Memory decline reported by the participant or family member for at least 6 months. * Meets the diagnostic criteria for the target disease and is clinically diagnosed with mild cognitive impairment due to Alzheimer's disease or mild, moderate, or severe Alzheimer's dementia. * Able to complete clinical scale assessments and blood sampling. * Able to undergo brain magnetic resonance imaging (MRI) or amyloid-beta positron emission tomography (Aβ-PET) examinations using the tracers specified in the study protocol. * Written informed consent provided by the participant or a legally authorized representative. * Able to complete study follow-up. * Participants with a known allergy to components of the exposure medications will be assigned to the non-exposed group. Exclusion Criteria: * Cerebrovascular disease, traumatic brain injury, thyroid dysfunction, vitamin deficiency, or other diseases sufficient to cause cognitive impairment. * Malignant tumors unrelated to the target disease, hematological diseases, severe psychiatric disorders, depression, or anxiety disorders. * Severe dysfunction of major organs, including the heart, brain, liver, or kidneys. * Infectious diseases, including HIV or HBV infection. * Pregnancy, breastfeeding, or plans for pregnancy in the near future. * Gastrointestinal diseases that may affect drug absorption. * Use of medications affecting cognitive function within 4 weeks before enrollment. * Recent participation in or current participation in another trial.