Alzheimer's disease (AD) is the most common cause of dementia, which severely injures multiple domains of cognitive functions in the aging people, bringing heavy burden to the society and families. Studying the cognitive brain damage mechanism of subjective cognitive decline (SCD), the preclinical stage of AD, would provide great opportunities for understanding the pathogenesis of AD and clinical value for early diagnosis and intervention in AD. The project intends to utilize amyloid-PET for screening and then employ the comprehensive neuropsychological examination combined with multi-modal neuroimaging techniques to study the brain functions and structures of the normal aging and SCD. The imaging data would be analyzed from several levels, including the cognitive dimensions, brain activation patterns, and especially functional and structural networks to establish the models of normal and pathological cognitive aging, which mainly be modulated by frontal-parietal control system. We aim to establish models of normal and pathological cognitive aging. Furthermore, the longitudinal data of SCD population would be collected to study the dynamic changes of brain networks so as to explore the progressive mechanisms of AD on brain networks and to construct a high-precision multi-modal model for early diagnosis