The observational study recruits participants from clinics and communities with cognitive impairment. Healthy volunteers will also be recruited as controls. Longitudinal observation of these participants will help demonstrate AD biomarkers' significance during AD pathogenesis.~The investigators aim to build an aging population cohort covering the AD continuum and explore key biomarkers for AD. All participants will have multi-modal MRI scanning, PET scanning with different tracers, and blood test. With MRI scanning, the investigators are exploring the effect of neurovascular coupling in AD pathogenesis. In addition, the investigators are trying to find patterns/mapping of AD biomarkers with PET and blood tests. Beyond this, more neuroimage markers and digital biomarkers will be tested in the cohort.
The goal of this observational study is to learn about neuroimage and biomarkers in the Alzheimer's continuum. The main questions it aims to answer are:~How is the neurovascular coupling during AD pathogenesis?~How is the pattern/mapping of alterations in AD biomarkers? Participants will be observed and visit the research center annually to perform multi-modal MRI, PET, neuropsychological tests, and blood tests.