NeuroCare Community Project: A Community Based Prospective Observational Study for Early Alzheimer's Detection in HK

Inclusion Criteria: * Mentally capable of providing informed consent, with or without an informant present * Willing and able to undergo blood draw and complete study related assessments; willing to be contacted for follow-up Exclusion Criteria: * Lacks capacity to consent even with an informant present * Refuses or is unable to provide blood samples or complete essential assessments * Currently enrolled in another clinical trial that could interfere with this study * Known illness that prevents longitudinal follow up or uncontrolled medical illness such as neurodevelopmental disorder, neurodegenerative disease, epilepsy, central nervous system infection, neuroinflammatory diseases, brain tumor, cerebrovascular diseases, history of major psychiatric illness, history of major head injury with altered consciousness, sexually transmitted disease including HIV and syphilis, visual and auditory disability, history of alcohol dependence, substance use disorder, systemic autoimmune diseases such as systemic lupus erythematosus and rheumatoid arthritis, or malignancy. * Active delirium or evidence of reversible/secondary causes of cognitive impairment (e.g., vitamin B12 deficiency, hypothyroidism) until treated/ stabilized