This study adopts a prospective Cohort study design, constructing a single-center Cohort study by recruiting patients with Alzheimer's disease (AD) who are positive for AD biomarkers. First, the investigators aim to establish a Cohort study of AD patients with positive biomarkers, thereby reserving suitable patient resources for future AD-related clinical trials. Second, based on the established Cohort study, the investigators will explore the associations between AD-related biomarkers and clinical manifestations among the elderly population in China, and identify potential risk factors influencing the progression of AD. Third, according to the identified risk factors for AD progression, the investigators will construct a risk early warning model for the progression rate of AD based on biomarkers, in order to achieve early identification and precise prevention and control of the progression risk of AD.